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Full text of "Handbook of artillery : including mobile, anti-aircraft and trench matériel"

GIFT OF 




183228 2( 



Ordnance Department Document No. 2033 



HANDBOOK OF ARTILLERY 

INCLUDING 

MOBILE, ANTI-AIRCRAFT 
AND TRENCH MATERIEL 



PREPARED IN THE OFFICE OF 
THE CHIEF OF ORDNANCE 



May, 1920 




WASHINGTON 
GOVERNMENT PRINTING OFFICE 

1920 












ORDNANCE DEPARTMENT 

Document No. 2033 
ffice of the Chief of Ordnance 



WAR DEPARTMENT, 

WASHINGTON, May, 1920. 

The following publication, entitled " Textbook of Artillery, Includ- 
ing Mobile, Anti-Aircraft, and Trench Materiel, - 1 ' is published for the 
information and guidance of all students of the Ordnance training 
schools, and other similar educational organizations. The contents 
should not be republished without authority of the Chief of Ordnance; 
War Department, Washington, D. C. 

BY ORDER OF THE SECRETARY OF WAR. 

PEYTON C. MARCH, 

General, Chief of Staff. 
OFFICIAL : 

P. C. HARRIS, 

The Adjutant General. 

(3) 



432322 



PREFACE. 



The data in this book is compiled for use in the Ordnance training 
schools and other educational organizations where a short, yet com- 
prehensive, survey of the existing calibers and types of guns and car- 
riages now in use by the United States Army is desired. On this 
basis, the descriptions and drawings have been made simple and 
technicalities have been reduced to a minimum, bringing out the 
differences and similarities of the various types of artillery materiel. 
. This publication has been prepared in the mobile gun carriage sec- 
tion of the Artillery Division. The general discussion on the design 
and characteristics of mobile artillery is intended for the instruc- 
tion of student officers and enlisted specialists schools. 

The first edition of this book is to be distributed to various educa- 
tional institutions for a trial use in their classes and the results of 
this trial should be productive of many constructive criticisms so that 
the second edition will more fully meet the varied needs of the 
schools and training units. The intention is to revise this book 
periodically, therefore suggestions and criticisms are cordially 
invited. Communications should be addressed to the Chief of Artil- 
lery Division, Office of the Chief of Ordnance, Washington, D. C. 

Murray H. Resni Coff. 



LIST OF CONTENTS. 



Page. 

List of illustrations .' 7 

Table of equivalents 14 

Brief history of guns and artillery materiel '. 15 

Artillery, classes of 21 

Mobile artillery, types of 21 

Guns, their functions and construction, including breech mechanisms 24 

Mounts for mobile artillery 28 

Recoil brakes and methods of counterrecoil 31 

Aiming devices and sighting methods. 39 

Accompanying vehicles 45 

37-millimeter gun materiel, model of 1916 50 

37-millimeter (1 pounder) gun carriage (Bethlehem) 56 

2.95-inch Vickers-Maxim mountain gun materiel (with pack outfit) 59 

75-millimeter gun materiel: 

Model of 1916 materiel 65 

Model of 1916 MI materiel 78 

Model of 1897 MI (French) materiel 80 

Model of 1917 (British) materiel 94 

Gun carriage limber, model of 1917 (British) 106 

Gun carriage limber, model of 1918 110 

Gun caisson, model of 1918 113 

Gun caisson limber, model of 1918 116 

3-inch gun materiel 118 

Guns, models of 1902, 1904, and 1905, and carriage, model 1902 120 

Gun limber, model of 1902 ]30 

Gun caisson, model of 1902 132 

Gun caisson, model of 1916 134 

Gun limber, model of 1916 .- 137 

Battery wagon, model of 1902 138 

Battery wagon, model of 1902 MI 139 

Store wagon, model of 1902 140 

Store wagon, model of 1902 MI 141 

Forge limber, model of 1902 .143 

Store limber, model of 1902 146 

Forge limber, model of 1902 MI 145 

Store limber, model of 1902 MI 146 

Battery and store wagon, model of 1917 147 

Battery reel, model of 1907 150 

Reel, model of 1909 MI 152 

Cart, model of 1918 155 

Wheels: 

56-inch (steel tired) 158 

57-inch by 3.5 inch (rubber tired) 158 

Reel, model of 1917, for caissons 159 

Automatic pole support 160 

(5) 



:/ 6 

Page. 

4.7-inch gun m*.t6jiel 131 

Gun and carriage, model of 1906 166 

Gun carriage limber, model of 1905 175 

Gun caisson, model of 1908 178 

Gun limber, model of 1908 180 

Gun caisson, model of 1916 182 

Gun caisson, model of 1917 186 

5-inch, 60-pounder gun materiel (British) 189 

Gun, Mark I, and carriage, Mark II 193 

Gun carriage limber, Mark II 196 

Ammunition wagon, Mark II 199 

Ammunition wagon limber, Mark II 203 

155 howitzer materiel, model of 1917 (Schneider) 207 

155 howitzer materiel, model of 1918 (Schneider) 211 

Howitzer and carriage, model of 1918 216 

Howitzer carriage limber, model of 1918 223 

Howitzer caisson, model of 1918 225 

155 gun materiel (Filloux) 229 

Gun and carriage, model of 1918 234 

Gun carriage limber, model of 1918 242 

6-inch gun materiel, model of 1917 (British) 245 

7-inch naval tractor mount, Mark V 249 

8-inch howitzer materiel (Vickers) 259 

Howitzers, Mark VI and VIII^, and carriages, Marks VI and VII 268 

Howitzer carriage limber, model of 1917 (Vickers) 278 

Firing platform and wagon, model of 1917 (Vickers) 281 

9. 2-inch howitzer materiel (Vickers). 283 

Howitzer and carriages, Marks I and II =. 288 

Howitzer transport wagon 296 

Howitzer carriage transport wagon 298 

Howitzer platform transport wagon 299 

240-millimeter howitzer materiel (Schneider) 300 

Howitzer and carriage, model of 1918 307 

Accessories 312 

Transport wagons and limbers 318 

Antiaircraft artillery 322 

3-inch antiaircraft gun materiel, model of 1918 326 

3-inch antiaircraft gun mount, model of 1917 340 

75-millimeter antiaircraft truck mount, model of 1917 354 

Trench warfare materiel 365 

3-inch Stokes' trench mortar, Mark 1 369 

6-inch Stokes' trench mortar, Mark 1 373 

Prospectus 378 



LIST OF ILLUSTRATIONS. 

Pago. 

Frontispiece. 

Sixteenth-century artillery 16 

French artillery, 1800-1850 18 

Recoil brakes and methods of counterrecoil : 

Hydraulic brake (throttling bar) 32 

Hydraulic brake (valve) 32 

Hydraulic brake (central throttling) 33 

Counterrecoil mechanism (spring, concentric columns) 34 

Oounterrecoil mechanism (spring, telescopic). . 34 

Hydro-spring recoil system 34 

Hydro-pneumatic recoil system with floating piston 35 

Hydro-pneumatic recoil system with fluid in direct compact with the air. . 35 

Counterrecoil mechanism (hydro-pneumatic, central buffing) 36 

Aiming devices: 

Elevating systems 40 

Panoramic sight 41 

Gunner's quadrant 42 

Accompanying vehicles : 

Tractors hauling artillery 46 

75 mm. gun carriage, mounted on trailer ^47 

37-millimeter gun materiel, model of 1916: 

Rear view of carriage in battery position : 49 

Carriage and ammunition cart, limbered 50 

Left side view of tripod mount in battery position 51 

Tripod mount in firing position 53 

Gun disassembled on the march (wheels and axles left in the rear) 54 

Gun and personnel on the march (ammunition cart left in the rear) 55 

37-millimeter (1-pounder) gun carriage (Bethlehem): 

Side view of carriage 57 

Rear view of carriage 58 

2.95-inch Vickers-Maxim mountain -gun materiel (with pack outfit): 

Carriage in firing position 60 

Pack outfit on mule back 61 

Rear view of carriage in battery - .62 

Detailed view of gun 63 

Side view of carriage in battery 64 

75-miUimeter gun materiel, model of 1916: 

Right side elevation of carriage 66 

Front view of carriage 66 

Plan view of carriage 67 

Rear view of carriage 68 

Left side view of carriage 69 

Breech mechanism 72 

Longitudinal section of recoil and counterrecoil mechanism 73 

Gun at maximum elevation 74 

Elevating mechanism 75 

Carriage and limber in traveling position 76 

Traversing mechanism 77 

(7) 



8 

75-millimeter materiel, model of 1897 Ml (French) : Page. 

Left rear view of carriage 81 

Front view of carriage 82 

Longitudinal section of gun and carriage 84 

Breech mechanism 85 

Right side elevation of carriage 87 

Traversing and brake operating mechanism 88 

Left side view of carriage 89 

Abatage positions of carriage 90 

Plan view of carriage 91 

Sight, model of 1901 92 

75-millimeter gun materiel, model of 1917 (British): 

Front view of carriage 94 

Left side elevation of carriage 95 

Rear and front elevations of carriage 96 

Rear view of carriage 97 

Breech mechanism 99 

Recoil-controlling system 101 

Elevating and range gear 103 

Traversing gear 104 

75-millimeter gun carriage limber, model of 1917 (British): 

Front view of limber 106 

Right side elevation of limber 107 

Rear and front elevations 108 

Rear view of limber 109 

75-millimeter gun carriage limber, model of 1918: 

Rear view of limber. 1] 1 

Front view of limber Ill 

Assembled views of limber 112 

75-millimeter gun caisson, model of 1918: 

Front view of caisson 113 

Assembled views of gun caisson 114 

Gun caisson and gun caisson limber, limbered 115 

75-millimeter gun caisson limber, model of 1918: 

Front view of caisson limber. . 116 

Assembled views of gun caisson limber 117 

3-inch gun materiel, model of 1902: 

Front view of carriage 119 

Rear view of carriage 119 

Left side elevation of carriage 121 

Gun, models 1902, 1904, and 1905, 122 

Breech mechanism 123 

Recoil -controlling mechanism 125 

Carriage and limber, hauled by tractor 126 

Carriage and limber in traveling position . . . .^ 126 

Range quadrant 127 

Rear sight 128 

3-inch gun limber, model of 1902: 

Rear view of limber 130 

3-inch gun caisson, model of 1902: 

Front view of caisson 132 

3-inch gun caisson, model of 1916: 

Front view, showing door swung upward exposing ammunition 134 

Front and side elevations of caisson. . 135 



9 

3-inch gun caisson limber, model of 1916: Page. 

Side and rear elevations of caisson limber 136 

Battery wagon, model of 1902 Ml: 

Rear view of battery wagon > 138 

Store wagon, model of 1902: 

Side view of store wagon 140 

Side view showing store wagon and limber, limbered 142 

Forge limber, model of 1902 Ml: 

*Top view showing interior of forge limber 143 

Assembled views of forge limber 144 

Store limber, model of 1902 Ml: 

Top view showing interior of store limber 146 

Battery and store wagon, model of 1917: 

Rear right side view of battery and store wagon 147 

Assembled views of battery and store wagon 148 

Battery reel, model of 1917: 

Left side view of battery reel . 150 

Reel, model of 1909 Ml: 

Rear view of reel 152 

Assembled views of reel 153 

Front view of reel 154 

Cart, model of 1918: 

View showing reel and cart, limbered 155 

Rear view of cart 155 

Assembled views of cart , 156 

56-inch wheel : 

Side view of wheel 158 

Reel, model of 1917, for caissons: 

View showing reel mounted on caisson 159 

Front and side elevations of reel 160 

Automatic pole support: 

Sectional diagram of pole support 160 

4. 7-inch gun materiel, model of 1916: 

View showing carriage and limber in traveling position 161 

Left side view of carriage in battery 162 

Assembled views of carriage equipped with band brakes 163 

Left front view of carriage equipped with band brakes : 164 

Assembled views of carriage equipped with tire brakes 165 

Front view of carriage equipped with tire brakes 166 

Breech mechanism 166 

Firing mechanism 167 

Longitudinal section of gun and carriage 168 

Front view of carriage equipped with band brakes 169 

Rear right view of carriage 170 

Elevating and traversing mechanisms 170 

Range quadrant 171 

Rear view of carriage equipped with band brakes 172 

Rear sight 173 

Front view of carriage equipped with tire brakes 174 

4.7-inch gun carriage limber, model of 1905: 

Front view of limber 175 

Assembled views of limber 176 

4.7-inch gun caisson, model of 1908: 

Right side view of caisson 178 



10 

4. 7 -inch gun limber, model of 1908: Page. 

View showing gun caisson and limber, limbered 180 

4.7-inch gun caisson, model of 3916: 

Right front view showing chest doors open exposing diaphragms 182 

Assembled views of gun caisson 183 

Front view of gun caisson 184 

4.7-inch gun caisson, model of 1917: 

Assembled views of gun caisson 187 

5-inch (60-pounder) gun materiel (British):' 

Rear left view of carriage in battery 189 

Carriage and limber in traveling position 190 

View showing trail connected to limber 191 

Rear right view of carriage 194 

5-inch (60-pounder) gun carriage limber, Mark II (British): 

Front view of carriage limber . . 196 

Rear view of carriage limber 197 

5-inch (60-pounder) ammunition wagon, Mark II (British): 

Front view of ammunition wagon 199 

Rear view of ammunition wagon 200 

Ammunition wagon and ammunition wagon limber, limbered 202 

5-inch (60-pounder) ammunition wagon limber, Mark II (British): 

Front view of ammunition wagon limber 203 

Rear view of ammunition wagon limber 204 

155-millimeter howitzer materiel, model of 1917 (Schneider): 

Right side view of carriage in traveling position 207 

Carriage in battery position (rear view) 208 

Front view of carriage in battery position 209 

Side view of carraige en route 209 

155-millimeter howitzer materiel, model of 1918 (Schneider): 

Traveling position of carriage and limber 210 

Assembled views of traveling position 212 

Detail view of howitzer . . . . 214 

Breech mechanism 215 

Firing mechanism 217 

Recoil and counterrecoil mechanism 218 

Longitudinal section of howitzer and carriage 220 

Quadrant sight 221 

155-millimeter howitzer carriage limber, model of 1918 (Schneider): 

Plan and right side elevations 224 

155-millimeter caisson, model of 1918 (Schneider): 

Rear view of caisson 225 

General assembled views 226 

Front view of caisson 228 

155-millimeter gun materiel, model of 1918 (Filloux): 

Traveling position (right side) 229 

Left-side view of carriage and limber in traveling position 230 

Rear view of carriage in battery position 231 

Carriage in traveling position (rear view) . ; 231 

Longitudinal section of gun and carriage 232 

Maximum elevation of gun 234 

Breech mechanism 235 

Breech mechanism and counterbalance cylinder 236 

Carriage in firing position 237 

Rear view of carriage in traveling position 238 

Accessories and caterpillar wheel shoes 239 

Elevating and traversing mechanism 240 



11 

155-miilimeter gun carriage limber, model of 1918 (Filloux): Page. 

Front view of limber 242 

Front view of limber, showing caterpillar wheel shoes, mounted on wheels . . 243 

Detailed view of limber 244 

6-inch gun materiel, model of 1917 (British): 

Plan view of carriage 246 

Left-side elevation of carriage .' 247 

7-inch naval tractor mount, Mark V: 

Carriage and limber in traveling position (front view) 249 

Rear view of carriage 250 

Left-side view of carriage in battery 251 

Carriage and limber in traveling position (rear view) 253 

Top carriage and axle details 254 

Assembled view of hydraulic brake 255 

View of axle mounted in track layer 256 

Side elevation of track layer ." 257 

Carriage in battery position, showing maximum elevation of gun 258 

8-inch howitzer materiel (Vickers): 

Carriage in battery position (Mark VI) 259 

Carriage and limber in traveling position (rear view) 260 

Carriage in battery position (Mark VII) 262 

Rear view of carriage, showing maximum elevation of howitzer 263 

Right-side view of carriage in battery 264 

Left-side elevation of Mark VI carriage 267 

Rear right-side of carriage in firing position 268 

Detailed view of howitzer (Mark VI) 269 

Breech mechanism of Mark VI howitzer 270 

Breechblock 271 

Firing mechanism 272 

Front view of howitzer carriage 273 

Elevating and traversing mechanism 274 

Howitzer carriage mounted on firing platform ; 275 

Sight assembled 276 

8-inch howitzer carriage limber, firing platform and wagon, model of 1917 
(Vickers): 

Limber in traveling position (front view) 279 

Materiel en train and in battery 280 

9.2-inch howitzer materiel (Vickers): 

Left-side elevation of carriages assembled 284 

Front view showing maximum elevation of howitzer 285 

Loading position, showing shell on tray ^ 286 

Longitudinal section of carriage 287 

Rear view of carriage, showing howitzer at maximum elevation 288 

Breech mechanism (Mark I) 289 

Breech mechanism (Mark II) 290 

Gear regulating recoil 291 

MetKod of loading, showing loading gear mechanism in action 292 

Right-side view of carriage in battery 292 

Traversing gear 1 293 

Sight assembled 294 

9.2-inch howitzer transport wagon (Vickers): 

Method of mounting howitzer 296 

Materiel en train. . 297 



12 

240-millimeter materiel, model of 1918 (Schneider): p age . 

Front view of carriage, showing maximum elevation of howitzer 300 

Materiel e"n train 301 

Carriage in loading position 302 

Method of loading the howitzer with rammer car 304 

Left elevation of carriage with howitzer at maximum elevation 305 

Breech mechanism 306 

Mounting the cradle 308 

Recoil and recuperator mechanism 309 

Elevating and quick-loading gear mechanism 310 

Mounting the top carriage 311 

Method of lowering platform 312 

Sight assembled 313 

Erecting frame in position 314 

Left-side view of carriage 316 

Mounting the howitzer 317 

240-millimeter howitzer transport limbers and wagons: 

Howitzer transport wagon 318 

Cradle transport wagon 318 

Top carriage transport wagon 319 

Platform transport wagon 319 

Antiaircraft artillery: 

Antiaircraft artillery in action 323 

3-inch antiaircraft gun materiel, model of 1918: 

Carriage in traveling position 325 

Carriage in battery position (front view) 327 

View showing outriggers folded 328 

Longitudinal section of carriage 329 

Breech mechanism 330 

View showing right rear outrigger with jack spade and float removed 332 

Side view of carriage in battery position 333 

Assembled view showing carriage in firing position 335 

Front view of trailer 336 

Sight on left side of carriage 337 

Sight on right side of carriage 338 

3-inch antiaircraft gun mount, model of 1917: 

View showing mount in action 340 

Longitudinal section of gun mount 341 

Right side elevation of gun mount 342 

View showing right side of mount 343 

Breech mechanism 345 

Vertical .section showing breech open 346 

Elevating and traversing mechanisms 349 

Left side elevation of gun mount 350 

7 5 -millimeter antiaircraft truck mount, model of \917: 

Truck in traveling position (right side view) 354 

Plan view of truck mount 355 

Sectional elevation of gun mount 356 

View showing truck mount in action 357 

Gun mount showing gun at maximum elevation 360 

Truck in traveling position (left side view) 361 

Firing and stability jacks 363 

Truck mount in battery position 364 



13 

Trench warfare materiel: Page 

Trench warfare 366 

Arrangement of trenches 367 

3-inch Stokes's trench mortar, Mark I: 

Mortar in action 369 

Front view of trench mortar 370 

Rear view of trench mortar 371 

fi-inch trench mortar, Mark I : 

Diagrams showing preparation of trench mortar for action 374 

Left side view of mortar 375 

Method of loading trench mortar 376 

Rear view of mortar 377 

Self-propelled caterpillar Mark II: 

Plan view 379 

Traveling position, front view 380 

Traveling position, rear view 381 



TABLE OF EQUIVALENTS. 



1 mil 3.37 minutes. 

1 degree 17.777 mils. 

1 meter (m) 39.37 inches. 

1 centimeter (cm) 0.3937 inch. 

1 millimeter (mm) 0.03937 inch. 

1 kilogram, (kg) 2.2046 pounds. 

1 dekagram (dk) 0.3527 ounce. 

1 gram '. 15.432 grains. 

1 liter 1 .05671 quarts (U. S.). 

1 quart (U. S.) 0.9463 liter. 

1 inch 2.54 centimeters. 

1 foot 0.3048 meter. 

1 yard 0.9144 meter. 

1 square inch 6.452 square centimeters. 

1 kilogram (kg) per square centimeter- 14.223 pounds per square inch. 

1 cubic inch 16.39 cubic centimeters. 

1 cubic foot 0.02832 cubic meter. 

1 cubic yard 0.7645 cubic meter. 

1 ounce 28.35 grams. 

1 pound 0.4536 kilogram. 

(14) 



A BRIEF HISTORY OF GUNS AND ARTILLERY 

MATERIEL. 



In taking up the study of guns, the student should know something 
of their history, the development of guns and gun carriages, and the 
reason for the various changes in ordnance materiel which have 
taken place from time to time. 

The first use of guns or cannon as a medium for hurling projectiles 
by means of gunpowder is buried in obscurity; we have knowledge 
of Chinese using a form of gunpowder, not, however, for military 
purposes, but for pyrotechnics, at a period long before the Caucasians. 

From the earliest times man has felt the want of arms that would 
kill at a distance, and the ingenuity of the talented has successively 
been taxed to produce such weapons. The readiest means at first 
was the throwing of stones or spears with the hand; but the effect of 
the missile proved so often insufficient that at once a desire arose to 
assist the muscles by the aid of some mechanical force. The sling 
was probably the first weapon used for hurling missiles. Its inven- 
tion is attributed to the Phoenicians or the inhabitants of the Balearic 
Isles, who were extremely expert in its manipulation. The sling was 
used for many centuries as a military weapon, and its last appearance 
was at the Huguenot War of 1572. 

The bow was probably invented about the same time as the sling, 
and for many centuries was considered the most effective offensive 
weapon in warfare. Great skill was attained by the ancients in its 
use, and many accounts are to be found relative to the extraordinary 
force and precision with which an arrow might be projected. The 
long-bow has always been more essentially the universal weapon, the 
cross-bow being a comparatively modern invention, and its use 
confined almost entirely to Europe. The cross-bow was greatly 
used for sporting as well as military purposes ; and it must have been 
a cross-bow that William Tell employed in his notable feat. The 
Genoese and Gascons were the most famous cross-bow men in the 
armies of Europe. The cross-bow of the fourteenth and fifteenth 
centuries were sometimes made with sights affixed to them. Some 
specimens possessed a back sight having three or more peepholes, 
one over the other, which were evidently intended as guides for 
elevation. 

The invention of gunpowder is possible to trace back to many 
centuries prior to the Christian era. Most writers upon this subject 
seem agreed that it was known to the Chinese and Indians, but the 
18322820 2 (15) 



16 



descriptions given are so vague that it is difficult to make the 
various accounts coincide. The earliest mention we have of gun- 
powder is in the Gentoo Laws, where it is mentioned as applied to 
firearms. This particular code is believed to have been coeval with 
the time of Moses. 

Gunpowder has been known in India and China far beyond all 
periods of investigation. There are many ancient Indian and 
Chinese words signifying weapons of fire, " heaven's thunder," 
" devouring fire," "ball containing terrestrial fire," and such like 
expressions. 

The ancient Indians made great use of explosives, including gun- 
powder, in pyrotechnical displays. The introduction of powder 
into Europe took place early in the Christian era; some believe it was 
brought by the Moors into Spain and others that it came through 
the Greeks at Constantinople. Both may be correct, but certain it 
is that it, or a substance closely akin to it, was used at the siege of 

Constantinople in A. D. 668. 
The Arabs, or Saracens, are 
said to have used it in A. D. 
690, at the siege of Mecca. 

The earliest mention of 
guns we have is that Seville 
was defended in 1247 by can- 
non throwing stones ; Mibela 
in Spain was also defended by 
a machine resembling can- 
non, when besieged in 1259; 
in 1273, Abou Yousof made use of cannon throwing stone balls at the 
siege of Sidgilmessa; and in 1308, Ferdinand IV of Castile, at the siege 
of Gibraltar, employed guns (or Marquinas de Truenas); and in 1311, 
Ismail attacked Bazas, a town of Granada, with machines throwing 
balls of fire with a noise resembling thunder. These seem to 4 confirm 
the opinion that the use of cannon and powder was known to the 
Arabs or Moors and introduced by them into Spain, from whence it 
spread over Europe. 

In the chronicle of the town of Ghent for 1313 it is stated that the 
town was possessed of a small cannon; and in the records of the 
Florentine Republic mention is made in the year 1325 of two officers 
being ordered to manufacture cannon and iron bullets for the defense 
of the castles and villages belonging to the Republic. The first 
German cannon belonged to the town of Amberg, and bears the 
date of 1301. The English appear to have imported them from 
Flanders, for King Edward III in 1327 employed some Hainaulters 
who used them in his war with the Scotch. In 1331 cannon were 
used by the King of Granada against Alicante, in 1339 at the siege of 




ARTILLERY OF THE SIXTEENTH CENTURY. 



17 

Puy-Guillem, and in the same year at the siege of Cambray by 
Edward III, in 1340 by Lequesnoy before Mirepoix, in 1345 before 
Monsegur, and in 1346 at Crecy; we have many instances of cannon 
being used in the second half of the fourteenth century. About 
1350 the North German knights had iron guns, and a little later the 
Free Hanse Towns armed themselves in the same way. In the year 
1356 appear large amounts in the accounts of the town of Nuremberg 
as having been spent in purchasing cannon and guns; and in 1365 
Duke Albert of Brandenberg defended Einbeck very effectually 
"with fire boxes." 

The first records show that the Huns used artillery at the siege of 
Cividale, Italy, in 1331. The materiel was, of course, very crude and 
its effectiveness at that time depended largely upon the smoke and 
noise produced. The barrels, or cannons, in those days were con- 
structed of wood, wrapped with wire or iron bands, and the pro- 
jectiles were of stone. These guns were not mobile guns in any 
sense; they were transported with the utmost difficulty, and were 
subject to capture by sudden raids of the enemy. 

The British were the first to actually bring the guns out into the 
field of warfare. They appeared at the Battle of Crecy in 1346, 
much to the dismay of the enemy. They shot anything that would 
go into the barrels of the guns, even bundles of arrows. The ord- 
nance department of Edward III consisted of 340 men, with but 12 
artillerymen, showing that at that time not much attention was paid 
to what is now an indispensable arm of the service. In 1415 the 
numbers had increased to 25 " master-gunners " and 50 "servitour- 
gunners." The gunner was the gun captain and had general charge 
of the gun and stores. In action he laid the piece and did the actual 
firing. 

The early cannon of Europe were known by various names in the 
different countries. In Italy they were known as bombardes, 
probably derived from "a bombo et ardore" on account of the 
great noise which the firing of them occasioned. The French called 
them "quenon" or "cannon," the Germans "buchsen" or "boxes," 
and the Netherlanders "voghdeer" or " veugliares." Besides these 
terms there were many others applied to the various models, but it 
was not until the commencement of the fifteenth century that cannon 
were classified and named according to their size. Cannon was not 
adopted or manufactured in France until 1338, and even for many 
years afterwards the French looked upon those nations who used 
them as barbarians. The early cannon were made of wrought not 
cast metal, the first account we have of cast cannon being in 1378, 
when a founder named Aran, at Augsberg, in Germany, cast 30 of a 
metal composed of copper and tin. In 1413 Mahomed II, at the 
siege of Constantinople, had an enormous cast cannon. The bore 



18 




19 

is said to have boon 48 inches in diameter and the stone bullet to 
have weighed 600 pounds. 

The greatest example of artillery in the fifteenth century was at 
the siege of Constantinople in 1453, by the Turks. They used a type 
of mortar that hurled huge stones, some weighing 700 pounds. 
Some of these guns survived to engage the British in 1807; the 
majority of artillery at that date was for siege work. Barons who 
had quarrels with their neighbors would rent ordnance and go out 
and batter down their castles. 

In the Italian wars waged by Charles VIII of France, artillery 
played a conspicuous part. However, they lacked the necessary 
mobility and, consequently, were captured and recaptured several 
times in a single engagement. At that, artillery had done some 
excellent work before small arms had attained any prominence. 
Although field artillery was introduced in the Hussite Wars, 1419 to 
1424, it was not until the Thirty- Years War that they really displayed 
a mobile nature. The French had invented the limber, and the con- 
nection between it and the gun trail was made with a rope. The 
first gun that was moved by horsepower was mounted on an oblong 
frame, the gunner sitting directly behind the piece. The forepart of 
the oblong was mounted on two wheels and the rear end was supported 
by the horse which was inside of the oblong frame. The majority 
of the guns were 4-pounders, for as yet no way had been devised for 
the proper transportation of the heavier guns. 

About the middle of the eighteenth century, guns were either 24, 
12, 6, or 3 pounders; the units were divided into brigades of 4, 5, and 
6 guns respectively, and began to be separated into heavy and light 
units. Each field gun was drawn by four horses with a cannoneer on 
each of the lead horses. The ammunition carried was 100 rounds of 
solid shot. 

The howitzer, needed for its high angle of fire, put in its appearance 
in 1785, being introduced by the French Army. Horse artillery 
appeared in the French Army in 1791. In 1800 the horses were 
paired off with a driver on each near horse as is done to-day. In 1808, 
at Vimera, the first shrapnel came into use. It was known as case 
shot and the type used by Napoleon had a fuze that could be used for 
two different ranges. Napoleon also introduced the idea of massing 
artillery along a long front. Between 1860 and 1870 rifling appeared; 
this caused sighting to be given greater consideration, as a rifled gun 
shoots very accurately. During our Civil War the smoothbore was 
generally used, although rifled guns had made their appearance 
toward the close of the conflict. Direct laying was the only method 
of fire employed at this time. With the breechblock came the 
quick-firing gun. This called for a recoil mechanism, in order that 
the lay of the piece would not be seriously disturbed as a result of 



20 

firing. The vast amount of smoke produced with the powder then 
in use hid the target from the gunner and, unless quite a wind was 
blowing, the shooting was slow, but with the development of smokeless 
powder in the late nineties, this latter fault was done away with and 
rapid firing was possible. The first shields were put on the guns 
about this time also, protecting the gun personnel and making the 
piece more difficult to put out of commission. 

The recent great struggle in Europe has brought about conditions 
and problems which heretofore have never existed in warfare. To 
meet these, sweeping changes have been made in almost every arm 
of the service, but probably the greatest and most radical change 
has been the motorization of the artillery. 

Heretofore successful advances by the troops were limited to 
comparatively short distances, due to the impossibility of advancing 
artillery, ammunition, and supplies over grounds which are often 
muddy, full of shell holes, and otherwise difficult to maneuver with 
enough rapidity to keep up with the advancing infantry troops. 
The problem of transporting army equipment in the field led to the 
introduction of tractors and motor trucks. 

The development of the caterpillar tractor used for hauling field 
artillery, which is able to negotiate almost any kind of terrain on the 
battle field, led to the question of the possibility of mounting guns 
directly on a self-propelled vehicle equipped with caterpillar treads. 
Early in 1918, an 8-inch howitzer was mounted on a self-propelled 
caterpillar and was fired at angles of elevation varying from to 45 
with very satisfactory results. This experimental caterpillar was 
tested, and it was found to be practical, easy to maneuver, and able 
to withstand the firing strain of the howitzer. As a result of this 
test, several types of experimental self-propelled caterpillar units 
are being built with armaments varying from 75-millimeter guns to 
240-millimeter howitzers. 



ARTILLERY. 



Artillery has come to mean all firearms not carried or used by hand, 
excepting machine guns. Artillery is divided into two general classic 
fications: Artillery of position and mobile artillery. 

Artillery of position is that which is permanently mounted in forti- 
fications. 

Mobile artillery consists of two classes: First, the artillery designed 
to accompany an army in the field; second, railway artillery, which 
requires tracks for its transportation. The first type only is dis- 
cussed in this book. 

MOBILE ARTILLERY. 

In designing any gun intended for use in the field, there are two 
important requirements power and mobility. Granting that a 
general type of gun has been decided upon, it is evident that any 
increase in either of these two factors is at the expense of the other. 
It is necessary to balance the two, keeping in mind the specific purpose 
of the gun under consideration. We thus find it necessary to have 
several distinct classes of guns, ranging from the very powerful and 
almost immobile, to the very mobile and comparatively weak. The 
general classification is heavy field, light field, mountain guns or 
pack howitzers, trench mortars, and infantry accompanying guns and 
howitzers. 

Besides this classification, based upon power, there is a second, 
based upon the shape of the trajectory. For the attack of targets 
that can be reached by it, flat trajectory fire is prefesred on account 
of its power and accuracy. Cases frequently arise, however, where 
such fire is useless, either the gun or its target being so concealed and 
sheltered by intrenchments or the condition of the terrain that higher 
angles of departure and fall become necessary. 

To provide for both cases, there are two or three types of 
weapon the long gun for flat trajectory, the shorter howitzer for 
curved trajectory, and sometimes the still shorter mortar for high- 
angle fire. We thus subdivide our original classes and distinguish, 
for example, the light field howitzer, the heavy field gun, etc. Evi- 
dently the number of separate calibers that might be adopted to 
make up a complete series of types is very large. But it is impor- 
tant to reduce this number to a minimum, both from considerations 
of economy and also to avoid complication in ammunition supplies. 

Guns were ordinarily intended for attack of targets that can be 
reached by direct fire; that is, by fire at angles of elevation not exceed- 

(21) 



22 

ing about 15. For the attack of targets that are protected against 
direct fire and for use in positions that are so sheltered that direct 
fire can not be utilized, curved fire that is, fire at elevations exceed- 
ing 15 is necessary. There is, therefore, provided the howitzer, a 
short gun designed to fire at comparatively large angles of elevation. 

Field guns are now designed which permit fire at elevations as 
high or higher than is permitted by the howitzers. This is partic- 
ularly true of anti-aircraft guns and those designed for use against 
entrenched positions. This development is an improvement in the 
effectiveness of the field gun, -but it will not eliminate the use of 
howitzers of equal mobility, as the latter use projectiles of much 
greater weight than that of same caliber gun materiel. 

The original American plan of field artillery design provided for 
each caliber of gun a howitzer of equal degree of mobility. In fur- 
therance of this idea and to reduce to a minimum the number of 
calibers of mobile artillery and thus simplify as far as possible the 
supply of ammunition, the calibers of the guns and howitzers were 
so selected that while both guns and howitzers fulfilled the require- 
ments as to weight and power for each degree of mobility the caliber 
of each was the same as that of the gun of the next lower degree of 
mobility. That is, the howitzer corresponding in mobility to one of 
the guns is of the same caliber as the next heaviest gun. The recent 
developments in American artillery, as well as the introduction of 
artillery of foreign design into the American service, have sustained 
this principle. 

Under ordinary conditions the 3-inch field gun with its weight of 
about 3,900 pounds behind a six-horse team, is about as powerful a 
gun as can follow an army in motion. For this reason a gun of ap- 
proximately this caliber has been adopted by most nations as the 
principal field gun. 

The artillery of all military powers now comprises what are known 
as " rapid-fire " or " quick-firing " guns. This designation is too firmly 
established to be changed, although it can not be considered as accu- 
rately descriptive since rapidity of fire is characteristic of nearly all 
modern types. The real distinguishing mark of a rapid-fire gun is that 
its carriage does not move materially in firing; instead, the gun recoils 
on the carriage and is returned to the firing position by springs or 
their equivalent. There are a number of other features, some of 
which are found in all rapid-fire models; but these are of secondary 
significance and either old ideas which could not be worked out 
practically before the development of the gun-recoil carriage or else 
improvements developed since in the effort to get the best results out 
of it. For example, it is useless to attach shields to a rigid carriage, 
for, since the cannoneers have to stand clear to avoid the recoil, they 
can not take advantage of them. Mechanism for traversing the 



23 

piece on its carriage is unnecessary with the rigid system, but be- 
comes necessary as soon as we adopt a carriage that remains more or 
less firmly anchored to the ground. Fixed ammunition and instru- 
ments for indirect laying are not essentially a part of either a rigid or 
a gun-recoil system; they are sometimes used with the former and 
occasionally, but rarely, omitted from the latter; but they have their 
full value only in rapid-fire material. 

Our mobile artillery is divided into the following classes: 

(a) Divisional artillery, such as the 3-inch, 75 millimeter guns, and 
155 millimeter howitzers. 

(6) Corps artillery, such as the 4.7-inch and 155 millimeter guns. 

(c) Army artillery, such as the 8-inch and 240 millimeter. Any 
caliber may, if required, be assigned to army artillery corps. 
U (d) Mountain or pack materiel transported on the backs of mules. 
For mountain service the system composed of gun and carriage must 
be capable of rapid dismantling into parts, none of which forms too 
heavy a load for a pack mule. The weight of the load including the 
saddle and equipment should not exceed 350 pounds. The mountain 
gun in our service is the 2.95-inch. 

(e) Infantry accompanying guns, such as 37 millimeter. 

(f) Trench mortars. 



GUNS. 



THEIR FUNCTIONS AND CONSTRUCTION. 

U A gun is a machine by which the force of expanding gas is used 
for the purpose of propelling a projectile in a definite direction." 

The gun consists of a metal tube, closed at one end, of sufficient 
strength to resist the pressure of the expanding gases, in which is 
placed a projectile designed to move through the tube. The force 
of the expanding gases acting on the base of the projectile causes 
it to start on its flight in a definite direction. When the charge is 
ignited, the explosion or rapid combustion of the powder gives rise 
by its decomposition to a large amount of gas, which tends to expand, 
and to occupy a space greater than that in which the powder was 
originally contained; consequently, it exerts a pressure in all direc- 
tions, and the energy developed is utilized in forcing the projectile 
from the tube. The major portion of the energy is distributed as 
follows : 

(a) Energy of translation of the projectile. 

(&) Energy of rotation of the projectile. 

(c) Energy of translation, in recoil, of the gun. 

(d) Energy of translation of the unburnt charge and gases. 

(e) Energy consumed in overcoming the passive resistance of the 
projectile. This resistance arises from the friction of the projectile 
against the walls of the bore, and of the rotating band against the 
driving edges of the lands. In the first stages it also arises from the 
cutting of grooves in the rotating band by the lands. 

The balance of the energy is expended by being lost as heat to the 
gun and that which remains in the gas as sensible or latent heat 

It may be readily understood that during the travel of the pro- 
jectile through the bore of the gun, from the instant of ignition of the 
charge until it has left the muzzle, tremendous rending stresses are 
set up in the tube. In the earlier days of ordnance construction, 
these stresses were met by sheer weight of metal; but as the weight 
of projectiles increased, with consequent increase in powder charges, 
this weight of metal became so great as to impede the desired mobility 
of the material. Consequently, forgings of refined and alloyed steels 
took the place of the castings or forgings of iron or simple steels. 

As explosives increased in power, the plain tube, even though built 
of alloyed steels, became incapable of containing the chamber pres- 
sures, even though of excessive weight. This problem was finally 
met through the construction of built-up and wire-wrapped guns. 

(24) 



25 

A gun is subjected to two fundamental stresses a circumferential 
tension tending to split the gun open longitudinally, and a longitudi- 
nal tension tending to pull the gun apart lengthwise. The longitudinal 
strength of a gun is usually greatly in excess of any requirements. 
It is easy to demonstrate that any homogeneous gun, i. e., a gun made 
of solid material and not built up, soon reaches the limit of thickness 
beyond which additional thickness is practically useless in giving 
strength to resist circumferential stress. This is due to the fact that 
the stress on the metal near the bore is far higher than that on the 
outer portion and soon reaches its maximum resistance, which addi- 
tional thickness of metal does not materially increase. The gun can, 
however, be arranged to withstand a considerably higher piessure 
by building it up on the principle of initial tensions. The inner lay- 
ers of the metal are thereby compressed so that the gas pressure has 
first to reverse this compression and then extend the metal. The 
gun barrel (or tube) supported by the contraction of the outer hoops 
will then be able to endure a gas pressure which can be expressed as 
proportional to the initial compression plus the extension, whereas in 
the old type of solid gun it was proportional to the extension only. 

In the built-up system, the outer jackets are shrunk one over the 
other so that the inner tube is placed in compression and the outer 
ones in tension. 

In place of one or more of the jackets, a thin wire or ribbon of steel 
is sometimes wound around the tube and has exactly the same effect 
as shrinking thin jackets one over the other. This type is known as 
the wire-wound gun. 

Guns may be composed of two, three, or more cylinders; though in 
practice guns are hardly ever built of more than four cylinders. All 
Army guns, except small howitzers or mortars, are of the built-up or 
wire-wrapped type. 

Rifling consists of a number of helical grooves cut in the surface of 
the bore. The soft metal of the rotating band of the projectile is 
forced into these grooves and causes the projectile to take up the 
motion of rotation as it passes through the bore. 

Rotation of the projectile around its longer axis is necessary for 
stability in flight. By twist of rifling is meant the inclination of one 
of the grooves to the element of the bore at any point. Rifling is of 
two kinds: 

(a) Uniform twist, or that in which the twist is constant through- 
out the bore. 

(6) Increasing twist, or that in which the twist increases from the 
breech toward the muzzle end of the bore. 

The twist of rifling is usually expressed in number of calibers length 
of bore in which it makes one complete turn; this is called the twist 
in calibers. The twist actually required at the muzzle to maintain 



26 

the stability of the projectile in flight varies with the kind of pro- 
jectile and with the muzzle velocity. 

If a uniform twist is used, the driving force on the rotating band 
will be a maximum when the pressure in the gun is at maximum, or 
near the origin of rifling. The increasing twist serves to reduce the 
maximum driving force on the band, thus lessening the danger of 
stripping it with resultant loss of rotation of the projectile. This is 
its principal advantage over the uniform twist, though it also reduces 
slightly the maximum pressure in the gun. The principal disad- 
vantage of increasing t wist is the continued change of form neces- 
sary in the grooves pressed in the rotating band as the projectile 
passes through the bore. This results in increased friction and a 
higher value for the passive resistance than with a uniform twist. 
If the twist increases from zero at the breech, uniformly to the muz- 
zle, the rate of change in the tangent to the groove is constant. A 
twist in this form would offer less resistance than the uniform twist 
to the initial rotation of the projectile. But to still further diminish 
this resistance, a twist that is at first less rapid than the uniformly 
increasing twist and later more rapid has been adopted for some 
rifled guns. 

The breech mechanism comprises the breech block, the firing mechan- 
ism, and the mechanism for the insertion and withdrawal of the block. 
There are two general methods of closing the breech. In the first 
method the block is inserted from the rear. The block is provided 
with screw threads on its outer surface which engage in correspond- 
ing threads in the breech of the gun. In order to facilitate insertion 
and withdrawal of the block, the threads on the block and breech 
are interrupted. The surface of the block is divided into an even 
number of sectors and the threads of the alternate sectors are cut 
a vay. Similarly, the threads in the breech are cut away from those 
sectors opposite the threaded sectors on the block. The block may 
then be rapidly inserted nearly to its seat in the gun, and when turned 
through a comparatively small arc, say one-eighth or one-twelfth of 
a circle, depending upan the number of sectors into which the block 
is divided, the threads on the block and in the breech are fully 
engaged and the block is locked. 

In the second method, a wedge-shaped block is seated in a slot cut 
in the breech of the gun at right angles to the bore and slides in the 
slot to close or open the breech. 

Variations of these two methods will be noted in the detailed 
descriptions of the guns which follow: 

The most notable variation from the above two types is the Nor- 
denfeld type of breech mechanism, a rotating block construction 
found on the French 37-millimeter and 75-millimeter, described 
more fully and illustrated in the description of these guns. 



27 

The breechblock is usually supported in the jacket of the gun or 
in a breech ring screwed into the jacket. The seat in the jacket 
being of greater diameter than could be provided in the tube, the 
bearing surface of the screw threads on the block is increased and 
and the length of the block may be diminished. 

The slotted screw breechblock is used to a great extent in oui 
service. Its advantages are uniform distribution in the gun of the 
longitudinal stress produced by the powder pressure and lightness 
permitted in the construction of the breech end of the gun. In the 
model of 1917, 3-inch anti-aircraft gun, however, and in the Ameri- 
can 75-millimeter gun, the sliding block operating vertically has been 
adopted for the reason that it permits of simpler mechanism for 
semiautomatic operations. 

Howitzers differ only slightly from guns in their construction. 
They are shorter in length and insomuch as the chamber pressures 
differ materially the necessity for the long jacket is eliminated. 
A shorter jacket, extending only a part of the length of the tube, 
shrunk on in the same manner, is generally used. 

Interior/ ballistics treats of the motion of the projectile while still 
in the bore of the gun. It includes the study of the mode of combus- 
tion of the powder, the pressure developed, and the velocity of the 
projectile along the bore of the gun. 

By means of the formulas developed, a study of interior ballistics 
has made it possible to design the granulation of the powder for a 
given gun so as to obtain the highest possible muzzle velocity with 
a given weight of projectile, while keeping the pressure along the 
bore within the limits imposed by the strength of the walls of the 
gun, and the weight of the charge low enough for convenient loading. 

After the calculation of curves of velocity and pressure are made, 
the walls of the gun are calculated to withstand the expected pres- 
sure at each point from breech to muzzle. 



MOUNTS FOR MOBILE ARTILLERY. 



A modern gun carriage is expected to stand steady on firing, so that 
in the first place it requires no running up, and in the second place 
it maintains the direction of the gun so that only a slight correction 
in elevation and direction is required after each round. The car- 
riage is maintained in position by the spade, which sinks into the 
ground, and by the friction of the wheels upon the ground. If the 
force of the recoiling gun were communicated directly to the anchored 
carriage the effect would be to make it jump violently, which would 
not only disturb the lay, but would prevent the cannoneers from 
maintaining their position. The hydraulic recoil brake is therefore 
interposed between gun and carriage. 

If the gun were rigidly attached to the carriage the latter would 
be forced back a short distance at each. round, and the wjiole of the 
recoil energy would have to be absorbed in that short motion. In- 
stead of this, the gun alone is allowed to recoil several feet and although 
the recoil energy is in this case greater than it would be if gun and 
carriage recoiled together, yet it is so gradually communicated to the 
carriage that instead of a violent jerk we have a steady, uniform 
pull, the only effect of which is to slightly compress the earth behind 
the spade. In a well-designed carriage the amount of this pull is 
always less than that required to lift the wheels off the ground by 
rotating the carriage about the spade. 

The only motion of the carriage which takes place is that due to 
the elastic bending and rebound of its parts under the cross strain 
set up in discharge. These strains are inevitable since the direction 
of recoil can not be always exactly in the line of the resistance of 
the earth behind the spade. This movement of the axis is known as 
jump and must be determined by experiment for the individual 
piece in its particular mounting. 

The principal parts of the typical gun carriage are the cradle; 
a device for mounting the cradle called in the different models a 
rocker, pintle yoke, or top carriage; the trail; the wheels and axle. 
The gun slides in recoil on the upper surface of the cradle and the 
the cradle contains the recoil controlling parts. 

In the design of the carriage the constructional difficulty lies not 
so much in preventing the carriage from recoiling, but in preventing 
the wheels from rising off the ground on the shock of discharge. 
The force of the recoil of the gun, acting in the line of motion of the 
center of gravity of the recoiling parts, tends to turn the carriage 

(28) 



29 

over backwards about the point of the trail or center of the spade. 
This force is resisted by the weight of the gun and carriage, which 
tends to keep the wheels on the ground. The leverage with which 
the overturning force acts varies with the distance of its line of action 
above the center of the spade; the leverage with which the restraining 
force acts varies with the horizontal distance of the center of gravity 
of the gun and carriage from the center of the spade. 

It follows that the steadiness of the carriage for a given muzzle 
energy may be promoted by four factors. 

(a) Increasing the weight of the gun and recoiling parts. This 
reduces the recoil energy. 

(b) Increasing the length of recoil allowed. This reduces the 
overturning pull. 

(c) Keeping the gun as low as possible, either by reducing the 
height of the wheels or by cranking the axle downwards. This 
reduces the leverage of the overturning force. 

(d) Increasing the length of the trail. This increases the lever- 
age of the steadying force. 

The well-designed gun carriage is one that combines these factors 
in a practical way, so as to give the greatest possible steadiness to 
the carriage, at the same time keeping within the limits of weight 
imposed by the necessity of mobility. 

Gun carriages are so constructed as to permit movement of the 
piece in either a vertical or horizontal plane. These motions may 
be simultaneous if so desired, and by a proper combination of the 
two motions, the axis of a gun may be aligned in any desired direc- 
tion within the limits of motion of its mount. The two kinds of 
motion are designated as follows: Rotation of the piece about a 
vertical axis, its inclination with the horizontal remaining unchanged, 
is called " traversing "; movement of the piece in a vertical plane, 
the horizontal projection of the axis of its bore remaining unchanged, 
is called "elevating." 

Gun carriages are provided with mechanisms for giving the pieces 
accurately controlled motion in both azimuth and elevation. Two 
types of elevating mechanisms are in common use. The first is the 
telescopic screw. This gives a considerable length of screw for a 
short assembled length and gives a rapidity of action (since the 
movement of the inner screw is equal to the sum of the pitches of 
the outer and inner screw for each turn of the pinion), combined 
with the nicety of adjustment of a single screw of fine pitch. 

In the second type 'the motion is communicated to rockers, 
attached to the bottom of the cradle, through the engagement of 
worms or pinions, with teeth cut on the circumference of the rockers. 



30 

This method is in use on all howitzers, and a great many guns. 
It allows for a very high angle of elevation, and when fitted with a 
quick-loading gear, allows for the rapid placing of the piece in load- 
ing position after firing. 

Movement of the gun in azimuth is accomplished in several ways; 
one is to pivot the cradle of the gun in a saddle which itself pivots 
on a horizontal transom of the trail. Another is to mount the gun 
and elevating gear on some form of top carriage, and pivot this 
top carriage over the axle. Still another is to traverse the whole 
piece along the axle, pivoting on the spade. This is a method used 
by the French in some of their designs. It has the disadvantage of 
only allowing for a small angle of traverse. 

The above principles of design are, of course, modified considerably 
in the case of semipermanent mounts which fire from platforms and 
for anti-aircraft guns which have special mountings suited to their 
special use. 



RECOIL. 



RECOIL BRAKES AND METHODS OF COUNTERRECOIL. 

The stresses to which a gun carriage is subjected are due to the 
action of the expanding powder gases on the piece. Gun carriages 
are constructed either to hold the piece without recoil or to limit the 
recoil to a certain convenient length. In the first case, the maxi- 
mum stress on the carriage is readily deduced from the maximum 
pressure in the gun. In the second case it becomes necessary to 
determine all the circumstances of recoil in order that the force 
acting at each instant may be known and the parts of the carriage 
designed to withstand this force and to absorb the recoil in the 
desired length. 

Assume the gun to be so mounted that it may recoil horizontally 
and without resistance. On explosion of the charge, the parts of 
the system acted upon by the powder gases are the gun, the pro- 
jectile, and the powder charge itself; the latter including at any 
instant both the unburned and the gaseous portion. While the pro- 
jectile is in the bore, if we neglect the resistance of the air, none of 
the energy of the powder gases is expended outside the system. 
The center of gravity of the system is therefore fixed, and the sum of 
the quantities of motion in the different parts is zero. The move- 
ment of the powder gases will be principally in the direction of the 
projectile. By formula, the weight of the gun, projectile, and 
charge being known, the complete relations between the velocity, 
time, and length of free recoil may be established. 

Thus far we have neglected all resistances and have considered 
the movement of the gun in recoil as unopposed. However, when 
the gun is mounted on a carriage the recoil brakes, of whatever 
character, begin to .act as soon as recoil begins, and consequently 
the velocity of recoil is less at each instant of travel than when 
unopposed. It is evident that the higher the resistance offered by 
the recoil brakes, the shorter will be the total length of recoil. A 
little consideration will show that if the total resistance to recoil is 
made constant throughout the recoil, its value will be less than the 
maximum value of a variable total resistance which will stop the 
gun in the same length of recoil. For a given length of recoil; the 
constant resistance will therefore produce less strain in the carriage, 
and for this reason is usually adopted, except where stability can be 
increased by using a variable pull. 
18322820 3 (31) 



32 




FIG. A. 



The recoil system of a gun carriage consists of a recoil brake for 
controlling the recoil and limiting its length, a counter-recoil mech- 
anism for returning the gun to the firing position and keeping it 
there, and a counter-recoil brake or buffer to soften the shock as the 
gun runs into the firing position. 

Recoil brakes of the friction type were formerly used. Pneumatic 
brakes were also used to some extent. Both have been entirely 
superseded by the hydraulic recoil brake. 

A hydraulic recoil brake consists of a cylinder filled with liquid 
and a piston. Relative movement is given to the cylinder and piston 
by the recoil, and provision is made for the passage of the liquid 

from one side of the head of the 
piston to the other, by apertures 
cut into the piston or in the walls 
of the cylinder. The power of the 
brake lies in the pressure produced 
in the cylinder by the resistance 
offered by the liquid to motion 
through the apertures. ! f the area of the apertures is constant, it is 
evident that the resistance to flow will be greater as the velocity of 
the piston or the velocity of recoil is greater. Therefore, the pressure 
in the cylinder, which measures the hydraulic resistance offered, will 
vary with the different values of the velocity of recoil. If, however, the 
apertures are constructed in such a manner that the area of aperture 
increases when the velocity of the piston increases, and diminishes when 
that velocity diminishes, the variation in the area of aperture may be 
so regulated, that the pressure in the cylinder will be constant, or will 
vary in such a manner as to keep the total resistance to recoil con- 
stant, or it may be made to vary in 
any manner desired. 

In figure A is shown one type- of 
hydraulic brake. It consists of a 
cylinder on the inner circumference 
of which are formed bars of varying 
cross sections, called throttling bars (T), piston (p), and piston rod. 
Either the piston rod is secured to the carriage, the cylinder moving 
to the rear with the gun, or the cylinder is secured to the carriage, 
the piston moving to the rear inside of the cylinder. 

Through the piston head are cut slots or apertures through which 
the liquid is forced from one side of the piston to the other as the 
cylinder, or piston, moves in recoil. Each slot has the dimensions 
of the maximum section of the throttling bar with just enough clear- 
ance to permit operation. The area of orifice open for the flow of 
liquid at any position of the piston is therefore equal to the area of 
the slots minus the area of cross section of the throttling bars, and 




FIG. B. 



is so determined that the resistance to the flow of the liquid, or the 
pressure in the cylinder, is made constant or variable, as desired. 

In another type of hydraulic brake the throttling bars are not 
used, but the varying apertures are obtained by cutting grooves of 
varying width or depth on the interior of the cylinder. 

Figure B represents another method of varying the throttling 
grooves. The piston (P) is held rigidly from turning and the valve 
(V) is rotated by means of a spiral groove cut in the cylinder walls, 
in which the lugs of the valve slide during recoil, thus rotating the 
valve and varying the size of the openings through the valve and pis- 
ton. This method is used to a considerable extent in British design. 

Figure C illustrates a method of central throttling. The throttling 
rod (R) has a varying diameter; this causes the amount of liquid, 
which flows between it and the hole in the piston (P) , to vary in the 
manner necessary for correct throttling. This method is used in 
some French designs. 

Counterrecoil, or the return of the gun to battery after completion 
of the recoil, may be effected by springs or by compressed air cylin- 
ders; the latter, in connection with 

the recoil brake, forming the hydro- . | [ p^ \ ~ 

pneumatic recoil system. (V c= Z__ J ^~ 

The spring method of effecting | ~f\ 

counterrecoil may be used in all 
gun carriages on which the gun 

recoils in the direction of its axis. These include pedestal mounts, 
barbette carriages, turret mounts, and all wheeled carriages as shown 
in figures F arid G. 

In the smaller carriages of these types the springs, initially com- 
pressed to the desired amount, may be placed between the piston 
and the rear end of the hydraulic brake cylinder which is lengthened 
for that purpose. 

In some carriages of this type the hydraulic brake cylinder moves 
with the gun in recoil, the piston being stationary. In such construc- 
tions the springs are usually placed around the hydraulic brake cyl- 
inder, and are compressed between a flange on that cylinder in front 
and some fixed part of the carriage in the rear. 

In larger carriages the springs are arranged in separate cylin- 
ders with pistons of their own, two to four of these spring cylinders 
being required, see figures F and G. 

Figure D shows a spring counter-recoil mechanism (spring recu- 
perator) consisting of two concentric columns of springs. 

It is sometimes necessary to use telescopic springs as shown in 
figure E, when a single column would not allow sufficient recoil. 

These and other arrangements of counterrecoil springs will be further 
discussed in the description of the carriages to which they pertain. 



34 







oooooooooooo o 
>oooooooooo< 






o 






"joooooooooo 
[>oooooooooo< 







DOOOOOO o o o o {_ 








oooooooooooL 




9 


)OOOOOOOOO O<|~ 




- 




ooooooooooon 





FIG. D. 



FIG. E. 



Compressed gas (either air or nitrogen) is now very generally used 
to effect counterrecoil. Figures H, J, K, and L are diagrams of two 
designs of hydropneuniatic recuperators. 

In Figures H and J the recuperator piston (P) forces the oil from 
the recuperator cylinder into the gas reservoir through the port 
(A) when the gun recoils. Thus the gas is compressed and the 
necessary energy stored up to return the gun to battery. The piston 
may be attached to the gun and move with it, the cylinder being 
fastened to the carriage, or the cylinder may move and the piston 



iRRIMGJ 




FIG. f=- IN-BAT- TERV OR F1RIMC3 ROSITIOM 



/SPRIMC3 




F"IG.Gi EIMP OF" IREICOIL- 

- SRRIMG RECOIL- 



rod be fastened to the carriage. The gas is given sufficient initial 
compression to hold the gun in battery at all elevations. 

The type of recuperator shown in figures K and L is similar in 
operation to that of figures H and J, but in the latter design the oil 
is separated from the gas by the floating piston (FP). 



AIR 




RIS-TOM(FP) 



H IN-BA-TTETR^ OR F-|RNG 



FLOAT-IMG PISTON 





FIG. K IN- BATTER V OR F"IR>MC5 F>OS|-TlOrH 




. L- ElfSP OF f?ETCOIL- 

HVORO-PINEIUMATIC REZCQJL- S^ 



WITH 



IM PIREICT OOMTAOT WITH THEI >AIR 



36 

The hydropneumatic recuperator (or counterrecoil mechanism) may 
be separated from the recoil brake or the two may be combined in 
one unit. 

The principal advantages of air cylinders over spring cylinders for 
counterrecoil are the reduction in weight and longer life. These 
advantages are especially important in long-recoil field guns or how- 
itzers designed to be fired at high angles of elevation. If springs are 
used the columns are long and heavy, being liable to breakage; while 
if air cylinders are used, the additional pressure needed when the 
guns are fired at high angles of elevation can be obtained by pumping 
more air into the cylinders. 

It is evident that the energy, in whatever way obtained, which 
effects counterrecoil, forms a part of the total energy of recoil. The 
total resistance to recoil is composed of the resistance offered by the 
brake, the resistance due to friction, the resistance either plus or 
minus due to the inclination of the top of the chassis or the recoil 

slides, and the resistance due to 

M B X _ JJ the counterrecoil springs or air cyl- 

/L c ^ "I (w L J inders, if there are such included 



OIL 



in the recoil system. 



FIG M The counterrecoil buffer is pro- 

vided for reducing the shock to the 

carriage as the gun is returned to the firing position by the counter- 
recoil mechanism. 

In figure M is shown a type of buffer which is used to some extent. 
It consists of a rod (B) which acts inside the hollow piston rod of the 
recoil cylinder. A similar method to this is to provide a separate 
cylinder in which a projection of the recoil piston acts during the last 
few inches of recoil. It may consist of a dash pot formed at the end 
of the recoil cylinder. 

The use of the counterrecoil buffer increases the stability of mobile 
artillery carriages by preventing their forward motion as the gun 
runs into battery. 

Modern field guns and howitzers are mounted so as to have a long 
recoil on their carriages when fired horizontally. When certain types 
of these guns are fired at high angles of elevation it is necessary to 
reduce the length of recoil to prevent the breech of the gun from 
striking the ground. This reduction is effected by a mechanism 
which automatically reduces the size of the orifices in the hydraulic 
brake as the gun is elevated. This is known as variable recoil. 

If no counterrecoil buffer is provided, the velocity of the gun when 
going into the firing position under the action of the counterrecoil 
springs or air cylinders is at a maximum just as it reaches that posi- 
tion. If an arrangement is made to automatically fire the gun when 
it has this maximum forward velocity, it is evident that the maximum 



37 

velocity of free recoil will be reduced by the amount of the forward 
velocity, and hence either the total resistance or the corresponding 
length of recoil, or both, can be materially reduced. Systems based 
upon this principle have been used abroad for small guns, such as 
mountain guns. The gun is caught by a pawl in the extreme recoil 
position and is loaded in that position. When it is desired to fire, 
the pawl is tripped, the gun runs forward, and is automatically fired 
as it reaches the firing position. The principal objections to this 
system, which is known as the differential recoil system, are the 
unsteadiness of the gun at the moment of firing and the possibility 
of the gun being turned over in a forward direction by the shock of 
counterrecoil if a misfire should occur. 

In artillery of position, the gun carriage is rigidly bolted to a fixed 
platform. Its mechanism is such as to allow the gun and the attached 
parts to recoil on firing. The nydraulic brake cylinder and its piston 
are attached, respectively,, to the moving and fixed parts of the car- 
riage, or vice versa, in such a way as to cause the piston to be drawn 
through the cylinder as the gun recoils. When constant total resist- 
ance is to be exerted by the recoil system, which is always the case in 
artillery of position, either the total resistance or the length of recoil 
may be assumed, and the other determined. While the assumption 
of a very long recoil would reduce the resistance and consequently 
the strain on the carriage and permit its parts to be made lighter, the 
necessary increase in the length of the recoil slides might overbalance 
the saving in weight. 

In carriages, such as mortar, anti-aircraft gun, and the latest type 
barbette carriages, all of which permit the firing of the gun at high 
angles of elevation, a very long recoil can not be used, because the 
distance from the breech of the gun to the supporting platform will 
not permit it. Furthermore, the use of a long recoil would necessi- 
tate the use of long and heavy columns of counter recoil springs. 
Lack of space also prevents the use of a long recoil on turret mounts. 

In disappearing carriages, the length of recoil is determined more 
by the necessity of giving the gun the proper movement in recoil than 
by limitation of the strains brought upon the carriage. 

With the exception of the disappearing and the older type of 
barbette carriages, the recoil for artillery of position is comparatively 
short. 

The construction of all modern wheeled carriages is such as to 
allow the gun to recoil in the direction of its axis. The resistance to 
recoil developed by the recoil system pulls forward on the gun and 
backward- on the carriage, tending to move the latter to the rear. 
Actual motion of the carriage to the rear is prevented by a spade 
sunk in the ground at the end of the trail of the carriage and so con- 
structed as to present a broad surface to the ground in the rear. 



38 

Under ordinary conditions the ground will resist a pressure of 40 
pounds per square inch of spade surface, and knowing the pressure 
developed by the pull of the piston rod, which is the only force acting 
on the carriage, the size of spade can be determined. 

Another effect produced by the resistance to recoil is a tendency to 
rotate the carriage around the point of support of the trail, or to 
cause the wheels to jump from the ground. Such a movement is 
very undesirable, as it interferes with the rapid aiming and firing of 
the piece. In order to prevent the wheels from jumping off the ground 
when the gun is fired, it is necessary that the product of weight of 
the carriage including its recoiling parts and the horizontal distance 
of the vertical through their center of gravity from the point of sup- 
port of the trail, should at any instant be greater than the product 
of the force opposing recoil and the perpendicular distance from its 
line of action to the point of support of the trail. The value of the 
total resistance to recoil, that will be just insufficient to cause the 
wheels to rise from the ground when the gun is in the firing position, 
is obtained by equating moments which will show that a value of this 
resistance small enough to prevent jump of the wheels in the early 
part of the recoil might still cause jump toward the end of the 
recoil, as the moment of the weight of the recoiling parts becomes less. 

It is evident that safety against jump can be maintained and the 
necessary length of recoil shortened if, instead of assuming a constant 
total resistance, we assume it as decreasing to such an extent as to 
remain parallel to a line showing the maximum permissible values of 
the total resistance to recoil and plotted as a function of the length of 
recoil. If the length of recoil is such as to provide a factor of stability 
when the gun is fired at horizontal, the carriage will be stable at all 
higher elevations, as the lever arm of the total resistance of recoil 
decreases as the gun is elevated. For this reason, reduction of the 
length of recoil with increase of elevation in howitzer carriages does 
not affect their stability. 

The initial strength of the counterrecoil spring columns or air 
cylinders is the force which they exert. against the gun in the firing 
position. This force must be great enough to hold the gun in that 
position at the highest angle of elevation at wilich it is to be fired, as 
well as to overcome the friction on the recoil sides as the gun runs 
forward to the firing position. 



AIMING DEVICES AND SIGHTING METHODS. 



Sights will be discussed briefly in this pamphlet merely to indicate 
their application to field, anti-aircraft, and trench materiel. 

In order that a projectile from any gun may hit the target, the 
gun must be fired at a certain angle of elevation depending on the 
range, the ballistic characteristics of the gun, and upon the relative 
level of the gun and target. It must be given such a direction to the 
right or left of the target as to offset the deviation of the projectile 
due to drift and wind. The sights of the gun provide means of de- 
termining when the axis of the gun has the predetermined direction. 

When the piece is sighted, both in elevation and direction by sight- 
ing directly 011 the target, the method is known as direct laying. 
This is precisely the same operation as sighting a shoulder rifle or 
pistol. The line of sight may be fixed in one of two ways. The first 
method is to use plain or open sights, the rear one of which has a 
peep, or notch, capable of adjustment in a vertical or horizontal 
direction. This rear sight is equipped with an arc reading in frac- 
tions of the range, or degrees, by which the necessary elevation can 
be set off. In some cases the rear sight is designed to automatically 
correct for drift; if not, the drift must be set off on a scale provided 
for this purpose on the rear sight. It is always well to bear in mind 
that the projectile follows the movement of the rear sight, going 
higher as the sight is raised, and to the right or left as the sight is 
moved to the right or left. 

The second method for direct laying is to use a telescope with cross 
hairs which takes the place of the open sights although its principle 
of operation is the same. 

The angle of elevation of a gun must be measured in the vertical 
plane through the axis of the piece. It frequently happens that a 
mobile piece must be fired under conditions in which the axis about 
which it turns in elevation (trunnion axis) is not level, thereby throw- 
ing the sight plane out of the vertical. If this is the case, the sight 
arm must be revolved about an axis parallel to the axis of the gun 
until the sight arm is vertical. Most wheeled mounts have such a 
provision made on their sights. 
Independent Line of Sight. 

In order to relieve the gun pointer from the responsibility of set- 
ting the elevation on the sight standard and elevating the piece, some 
guns are provided with what is known as the independent line of 
sight. It will be noted that the actual quadrant elevation of the 
piece consists of two parts: 

(a) The elevation necessary to reach the target if it were on the 

same level as the gun. 

(39) 




40 

(6) The correction to this elevation required by the difference of 
level of the gun and target (angle of site). 

With the independent line of sight the two parts of the quadrant 
elevation are applied to the gun independently. An intermediate 
rocker and two elevating systems, A and B, are provided as shown 
in Figure N. 

The sight is fixed to the rocker, and for direct fire the gun pointer 
manipulates the lower elevation system A, which moves the rocker 
as well as the gun in elevation. In this way the angle of site is auto- 
matically corrected, when the line of sight is brought upon the 
target. 

The other elevating mechanism, B, is between the rocker and the 
gun and is manipulated by another cannoneer who elevates the gun 

until the proper range appears 
on a range scale. 

The change in range does not 
affect the setting of the lower ele- 
vating mechanism, and the gun 
pointer is thus free to devote his 

FIG. N. , . . 

whole time to keeping his line of 

sight upon the target and is not compelled to take his eye from the 
telescope. The above method has the objection, however, that it is 
difficult to make the necessary correction in the range drum for differ- 
ence in level of trunnion axis. 

Various modifications of this general method of securing the inde- 
pendent line of sight are in use and will be discussed with the guns 
to which they pertain. 

The gun is said to be laid indirectly when it is laid by means other 
than aiming directly through the sights at the targets. 

The fire from modern field pieces is so accurate and destructive 
that it is always necessary to establish field batteries in position out 
of the view of the enemy for the sake of protection. Indirect sight- 
ing becomes then of necessity, the usual method of sighting such guns. 

The panoramic sight affords the means of aiming the gun in indi- 
rect laying by directing the line of sight on any object in view from 
the gun; at the same time it affords the advantage of a telescopic 
sight in direct or indirect aiming. 

This panoramic sight is a telescope so fitted with a rotating head, 
reflectors and prisms, that a magnified image of an object anywhere in 
view may be brought to the eye without change in the position of 
the observer's eye. 

The panoramic sight is often mounted in connection with the 
range-sighting mechanism, but in some cases in order to divide 
the duties of laying for direction and elevation, the panoramic sight 
is mounted on a shank on the left side of the cradle and used in 
laying for direction, while the range quadrant for laying in elevation 



41 



is placed on the right side of the cradle and used by another 
cannoneer. 

In connection with the range quadrant a range level is provided, 
which is a special form of clinometer. It is used in setting off the 
angle of site, thereby correcting for difference in level of the gun or 
target. The range quadrant is graduated in degrees or in fractions 
of the range (mils). In the case of howitzers, the different zones of 
fire are sometimes shown. 

While the use of the range quadrant separates the duties of the 
cannoneers in aiming, it does not comply with the conditions for the 

independent line of sight. The sight 

and range quadrant being attached to 
the cradle, both move in elevation with 
the gun. The independent line of sight 
permits of the gun being moved and set- 
in elevation without any change in po- 
sition of the sight used for direction 
aiming. 

Leveling plates or similar surfaces are 
provided on all guns and howitzers on 
which a gunner's quadrant (see p. 42) 
can be used in obtaining or checking 
the elevation. 

It is not the intention to go into de- 
tail in this handbook regarding the fire- 
control equipment employed for direct- 
ing the fire of anti-aircraft materiel, but 
as the development is so new, and they 
are so closely involved with artillery 
during operations, it is quite necessary to devote some space to the 
fire-control equipment. 

Many of the terms and instruments used in connection with anti- 
aircraft artillery are similar to those employed with field artillery 
materiel, but the methods of application in most cases differ. 

In the direct fire of anti-aircraft artillery the following angles 
resulting in the laying of the gun to the predicted future position 
of the target are involved. 

1. Present azimuth and elevation. These are obtained by direct 
sighting upon the target. 

2. Principal lateral and vertical deflections. 

3. Secondary lateral and vertical deflections. 

4. Superelevation. 

In the determination of the principal lateral and vertical deflec- 
tions, two methods of fire control have been established: 

1. Linear speed. 

2. Angular speed. 




PANORAMIC SIGHT, MODEL OF 
1917. 



42 



Each method assumes rectilinear travel of the target, i. e., that 
the pilot of the aircraft will fly a straight course at unchanging 
speed and constant altitude during the time required for the deter- 
mination of the fuse range, setting of the fuse, loading and firing 
the gun, and for the projectile to reach its point of burst. Each 
method is based upon sound mathematical reasoning and involves 
automatic apparatus of rather complex, but easily operated, mechan- 
ical and electrical design, in order to resolve the data required in 
the laying of the gun. 

In the first method the quantities required in the resolution of 
the formulae are : 




GUNNER'S QUADRANT, MODEL OF 1918. 

(a) Presentation (angle of approach), i. e., the horizontal pro- 
jection of the angle made between the vertical plane of sight and 
the axis of the fuselage of the airplane. 

(6) Engine speed of the target. 

(c) Altitude of the target. 

(d) Time of flight of the projectile to the future position of the 
target. 

The resolution of the formulas deriving the lateral and vertical 
deflection corrections is accomplished upon a device known as 
" Anti-aircraft artillery deflection computer." The readings ulti- 
mately obtained from this instrument are given in mils. They are 
transmitted telephonically or by direct announcement to the gun 
layers who immediately lay the gun to its future position, while the 



43 

telescope pointers remain sighted unon the present position of the 
target. 

The great advantage of this method lies in the fact that the pre- 
sentation and engine sDeed can be estimated with reasonable accuracy,. 
The altitude of the airplane is determined from altimetry stations, 
and the time of flight is known when fuse range has been determined 
from a telemeter. 

In the angular speed method the lateral and vertical angular 
velocity of the target is measured. These are multiplied by the total 
element of time mentioned in the aforesaid and gives the respective 
displacements. The fact that the angular velocity of an airplane in 
ordinary flight is never uniform makes this method more difficult of 
apprehension but as applied in our instrument design gives results 
appreciably better than the linear s^eed method and is consequently 
used more generally. The instruments resolve the lateral and ver- 
tical deflection corrections in mils and also the fuse range. These 
are telephoned to the gun layers who function the sighting system 
mechanisms. 

The element fuse range is required for two main purposes in anti- 
aircraft gunnery: (a) For the setting of the fuse, and (6) as a function 
in automatically giving superelevation to the gun i. e., the angle 
between the line of sight to the predicted future position of the 
target and the axis of the bore of the gun when ready to fire. 

Secondary deflections are required in making allowances for wind- 
age, ballistics, drift, etc. These are set by giving secondary move- 
ment to mechanisms of the sighting system. 

When firing, "indirect" or at night, which essentially is indirect 
fire, three elements pertaining to the predicted future position of the 
target are transmitted from this apparatus at the fire-control station 
in order to accomplish the laying of the gun and setting of the fuse: 

1. Azimuth. 

2. Quadrant elevation. 

3. Fuse range. 

Secondary deflections involve, in addition to those common to 
direct firing, corrections for parallax when firing "indirect." 

At night the alliance of listening apparatus and searchlights assist 
in accomplishing the resolution of the gun-laying elements at the 
fire-control station. 

Altimetry, which is a basic factor in the computation of the prin- 
cipal and secondary deflection corrections, is obtained in one of two 
ways : 

(a) Monostatic. 

The monostatic or one-station instrument is an optical device that 
determines the altitude by automatic triangulation through the coin- 
cidence of light rays along a self-contained base. 



44 

(6) Bistatic. 

This is a system in which two stations are set up and oriented 
along a base line of known length, frequently as great as 4,000 
yards. The height or vertical distance of the target above the base 
line is then determined geometrically by projecting its altitude 
horizontally into the vertical plane passing through this base line. 

When altitude has been determined, telementry, which involves 
the functions, angle of site, to the future position of the target and 
altitude, is readily accomplished with the aid of automatic devices. 

When firing against airplanes at night, searchlights are used to 
illuminate the objective. When it is able to find it and keep it in 
its field, firing can be conducted in the same manner as in day- 
time. Many sound detecting instruments have been made ; one of 
the recent types is the ''Paraboloid." A surface in the shape of a 
paraboloid, movable in azimuth and site, focuses the sound waves 
when its axis is placed in their direction ; they swing from one side of 
the focus to the other when the axis of the instrument is turned. 
The sound is received by trumpets placed on either side of the focus 
and joined in pairs to the ears of two observers who adjust the 
instrument, the one for azimuth, the other for site. 

Briefly, the foregoing describes the fundamentals of anti-aircraft 
artillery fire-control methods. Being the most precise form of 
gunnery, anti-aircraft artillery involves material capable of the 
highest degree of facility and accuracy in the automatic measurement 
of deflections and the maneuvering of its gun-laying mechanisms in 
order that effective fire may be conducted against a target whose 
movements are subject to such large displacements. 



ACCOMPANYING VEHICLES. 



In addition to the piece itself, a number of vehicles are necessary 
in batteries, sectors, and regimental organizations of field artillerj 7 
for maneuvering and serving the piece. The type of vehicles vary 
with the different guns and the various organizations. Some of the 
more common vehicles such as limbers, caissons, etc., are described 
in a general way in this chapter, while their special features are 
described in detail with the materiel with which they are issued. 
Other special vehicles such as reels, store and battery wagons, etc., 
are also described with the materiel to which they pertain. 

The caisson is essentially a conveyance for the transportation of 
ammunition in the field. It generally consists of a chest for ammu- 
nition mounted on two wheels and axle. In front it is fitted with a 
short pole having a lunette for attachment to other vehicles and in 
the rear with a pintle, to which additional vehicles may be attached. 
Various tools are usually carried on the caisson, and seats are pro- 
vided for the accommodation of the personnel. 

The limber is a two-wheeled vehicle designed primarily to increase 
the mobility and faciliate the maneuvering and deployment of field 
artillery. There are several types of limbers in use, the principal 
ones being the carriage and caisson limbers. 

The carriage limber is attached to the trail of the piece when 
traveling. For light field pieces, a chest for ammunition is pro- 
vided on the carriage limber. In the case of heavy pieces, the chest 
is dispensed with and the trail of the piece rests on the top section 
of the limber. A pole is provided at the front for horse or motor 
traction, and the rear is equipped with a pintle for attachment of 
the carriage. 

The caisson limber is used for hauling the caisson and is provided 
with a chest for carrying ammunition. 

The forge and store limbers are designed to carry supplies and 
equipment, the forge limber carrying the tools and supplies for the 
farrie'rs shop. The battery wagon and the store wagon are two- 
wheeled vehicles equipped with chests for tools, supplies, and spare 
parts. 

With batteries of heavier field artillery, some of the vehicles are 
dispensed with, especially the caissons, battery wagons, forge, and 
store limbers, the ammunition being carried in motor trucks, in which 
most of the spare parts and supplies are also carried. 

(45) 



46 




47 

Light field artillery is usually drawn by horses although some of 
these batteries are now motorized, i. e., hauled by either caterpillar 
tractors or motor trucks. 

In addition to this, provisions are made for a limited number of 
trailers for use in carrying light guns at high speed behind motor 
vehicles. These trailers are rubber tired and for high-speed condi- 
tions; the complete gun, with carriage, may be placed on this trailer 
instead of being transported on its own wheels. 

The recent struggle in Europe brought about problems which 
heretofore have never existed in warfare; and to meet these changes 
have been made in every arm of the service, but the greatest and 




75-MILLIMETER GUN CARRIAGE MOUNTED ON A 3-INCH FIELD GUN TRAILER. 

most radical change being the motorization of artillery. Mechanical 
transport is at this time in such a state of development that there 
is no reed of dwelling upon its numerous advantages over animal 
draft. 

The origin aj x heavy artillery was limited to guns emplaced in 
permanent fortifications and guns of large caliber which were only 
moved with great difficulty. Light horse-drawn guns and howitzers 
comprised the mobile artillery for use in the field. This type of 
artillery was ideal for quick action at short ranges. 

As the artillery became a more important factor, large caliber long- 
range guns were required. The movements of this heavy artillery in 
18322820 4 



48 

the field could only be accomplished in one way by motorizing 
it. The result is the development of the extremely mobile heavy 
artillery. 

In applying motor transportation to artillery, types of motor 
vehicles of widely varying capacity and duty are required. In most 
cases commercial cars and trucks are used, but in a few instances 
special types have been developed. Motor equipment is still under- 
going changes, all tending to produce apparatus of unfailing depend- 
ability and maximum mobility and flexibility. 

Motor apparatus of the following types have been selected as the 
most suitable for accomplishing this motorization: First, passenger 
cars, both light and heavy; second, motor cycles with and without 
side cars; third, trucks; fourth, four-wheeled trailers: and fifth, 
tractors of the caterpillar type. 

Passenger cars are furnished when on the march and when occupy- 
ing a position on the lines. Batteries are supplied with light touring 
cars, staff cars, and motorcycles with side cars. Battalion and regi- 
mental headquarters are also supplied with light touring cars and 
Westfield military bicycles. A motorcycle is ideal for liaison and 
work of similar nature requiring rapid transportation for one or 
two individuals. The motorcycle is particularly useful when trav- 
eling in convoy and for keeping the various units of an organization 
in close touch with each other. 

Motor trucks are necessary for carrying supplies and ammunition 
from the depots and distributing them to the various units. A great 
many trucks are required to insure unfailing supplies when artillery 
is in action. Because of 'the uncertain conditions of the roads back 
of the lines sturdy trucks that can pull through under the most 
unfavorable conditions are employed. 

In bringing the guns into position it is often necessary to cross 
ground plowed by exploded shells, to go through mud and deep sand. 
and to ford streams which can not be negotiated by a wheeled type 
of motor vehicle, thus the type of apparatus adapted for this purpose 
is the caterpillar tractor. 

The problem of the care and maintenance of motor equipment in 
the field is met by issuing the repair and artillery supply^ trucks to 
each battery supply and headquarters company of motorized artillery. 

The artillery supply truck is really a motorized store wagon carry- 
ing spare parts, tools, etc., for the particular kind of unit to which 
it is assigned. 

The artillery repair truck consists of a small machine shop mounted 
on wheels. Its equipment is complete, including a lathe, drill press, 
air hammer, forge, etc. Electric power is supplied by a small gen- 
erator driven by an individual gasoline motor mounted on the truck. 



49 

The equipment is designed to make all repairs in the field, both to 
artillery materiel and motor vehicles. 

The motor equipment makes transportation a comparatively easy 
matter, permitting it to be moved with rapidity, either on the offensive 
or defensive. The value of this equipment becomes more apparent 




as the nature of warfare changes from that of position to that of 
movement. 

Detailed descriptions of the above motor vehicles are given in 
separate handbooks pertaining to motor equipment materiel. 



37-MILLIMETER GUN MATERIEL, MODEL OF 1916. 



Experience has shown that the infantry can not carry out its 
mission, by its own weapons, except at prohibitive less of personnel. 
Our automatic rifle is practically useless for ranges greater than 
500 meters, and then only against personnel. The individual 
rifle does not offer the necessary volume of fire, while the rifle 
grenade, and even more so, the hand grenade, is a clcse combat 
weapon. Hence the taking of a machine-gun nest by a unit (con- 
sisting of an automatic rifle squad, hand bombers, and rifle grenadiers) 
attacking the flanks, will not prove very successful, particularly 
if machine-gun nests are echeloned to considerable depth, and 
executing cress fire. 

Such conditions calls for some form of artillery, effective at from 
400 to 1,500 meters, against both personnel and materiel, raid 




37-MILLIMETER GUN CARRIAGE AND AMMUNITION CART, LIMBERED. 

capable of immediate action. The field artillery is not available 
because of difficulty of communication and length of time neces- 
sary to get into action. The heavy artillery is not sufficiently 
mobile. Its dispersion is too great for small, definite targets, there- 
by calling for vast amount of ammunition, extremely difficult to 
transport. 

The necessity of providing an accompanying gun for certain units 
of infantry has led to the adoption of a 37-millimeter gun (devel- 
oped by the French Army) . 

The 3 7-millimeter. gun, also known as the 1 -pounder or infantry 
accompanying gun, is the smallest weapon of the field-gun type in 
use by the American Army. It is used by advancing infantry 
outfits, chiefly for destroying concrete machine-gun emplacements, 
outposts, and other points of resistance. Recent developments 
and modifications of this weapon have found wide application for 

(50) 



51 




52 . 

its use and, due to its extreme portability, this gun is adaptable for 
tanks, tractors, and aircraft. 

As this gun is intended to follow infantry over any kind of ground, 
its construction is designed to give great mobility. The personnel 
is organized for rapid fire; the possible rapidity of fire is 35 shots 
per minute. 

Each gun unit is composed essentially of two elements : 

(1) The gun on a tripod mount, capable of being set on wheels. 

(2) A light wagon serving as a limber and carrying ammunition, 
spare parts, and accessories. 

The gun and limber when joined are normally hauled by one 
horse or mule, but near the enemy they are separated and moved 
by man. 

In action the gun is operated by two men, one keeping it on the 
aiming point and the other loading and firing. The gun must be 
cocked by hand in order to load for the first round, but thereafter 
the counterrecoil of the barrel cocks the piece, and it is only neces- 
sary to open the breech mechanism, which ejects the case, insert a 
new cartridge, close the breech, and fire. 

When used as a tripod mount, it is separated into portable groups 
for transportation and each unit is carried by two men. One group, 
weighing 104 pounds, consists of the gun and cradle and the other of 
the trails, weighing 84 pounds. With the combination tripod mount, 
the gun is transported on a wheeled carriage which is limbered to a 
two-wheeled ammunition cart, drawn by one mule or horse. 

Weights, dimensions, and ballistics. 

Weight of gun and recoil mechanism (with flash hider and sight) . . . .pounds. . 104 

Weight of recoil group do 34 

Weight of barrel group do 38 

Weight df breech group do 18 

Weight of flash hider do. ... 2. 5 

Length of gun calibers . . 20 

Range (H. E. Shell Mark II) meters. . 3, 650 

Muzzle velocity .feet per second . . 1 . 204 

Weight of projectile pounds. . 1. 234 

Length of recoil inches. . 7-10 

Maximum ande of elevation degrees . . 21 

Maximum angle of depression do 14 

Amount of traverse to right do 22 

Amount of traverse to left do .... 16 

Weight of axle, complete pounds . . 36. 25 

Weight of wheels, each do 68 

Weight of trails (including pintle and float) do 84 

Diameter of wheels inches. . 37. 75 

Width of track do 33 

Weight of gun and carriage, complete pounds. . 360 

Over-all length of vehicle inches. . 75 

Over-all height of vehicle do 37.75 

Over all .vidth of vehicle . . . .do. . 57 



53 

The gun is composed mainly of a steel alloy barrel. A front clip 
of bronze and an aluminum jacket serve as supports and guides for 
the whole barrel. The breech housing is screwed to the rear end of 
the barrel and forms a receptacle for the breechblock. 

The breechblock is of the Nordenfeld type and with the exception 
of size is practically the same as that used on the French 75 milli- 
meter field gun. J t screws into the breech housing and is opened 
and closed by being rotated 156 degrees about its axis, which move- 
ment is limited in each direction by a stop. The breechblock is 
cylindrical in form, rotates in a threaded seat and is operated by a 
handle which when moved to the left causes the eccentric hole in 
the block to register with the bore and also operates the extractor 
thus ejecting the empty cartridge case. Pulling the lever to the 
right rotates the block so that the port in the block is drawn away 
from the bore and a solid surface containing the firing pin backs up 
to the base of the cartridge. 

The action of the powder gases on the breechblock at the moment 
of discharge produces the recoil of the united barrel and breechblock. 




TRIPOD MOUNT IN FIRING POSITION. 

The purpose of the recoil mechanism is to control and limit the recoil 
and to return the barrel to the firing position, at the same time pre- 
venting a sudden return which might disturb the aim of the gun. 

The recoil cylinder consists of a cylinder containing a piston, 
piston valve, counter recoil spring in three sections, and counterrecoil 
buffer. The piston rod, which is hollow and open at the piston end, 
is pierced with holes for the passage of oil both during recoil and 
counterrecoil. The piston is fitted with four holes for the passage 
of oil during recoil. This oil is allowed to pass through two parts 
of the piston; first, through the hollow portion of the piston rod, and 
second, through the holes in the piston head. The oil passages in 
the piston head are closed by the piston valve. The valve is held 
against the front face of the piston by a spring, closing the oil holes 
in the head during the counterrecoil stroke, thus slowing up the for- 
ward motion of the gun. The counterrecoil buffer is screwed into 
the front cylinder cap and eases the movement of the gun into 
battery, thus preventing excessive shock. The capacity of recoil 
cylinder is 2.75 pints and the extreme travel of piston is 11 inches. 



54 

The mount may be used either in the form of a tripod or with the 
axle and wheels attached. n the former case a front leg having a 
float adjustable to two heights at its lower end is used to support the 
front end of the mount, and the spread trails in rear equipped with 
spades form the other points of support. n the case of the wheels 
being used, the front leg is swung up and secured, and both trails 
are spread out to support the rear. 

The pintle, or gun mount, is in the form of a yoke, the upper end 
being fitted to receive the cradle trunnions. Each trail head is 
equipped with lugs which pivot on bearing surfaces in the lower end 
of the pintle. The trails, when spread, are kept in position by a 
removable transom, which also serves as a seat for the gunner. 

A Y-shaped frame, pivoted and secured to the pintle at its upper 
and lower ends, extends to the rear in the form of a fork and engages 
the nut housing on the traversing screw. The nut is turned in its 
housing by a small handwheel attached thereto, w^hich causes the 




GUN DISASSEMBLED ON THE MARCH (WHEELS AND AXLES LEFT IN THE REAR). 

nut and housing to move along the screw, thereby traversing the 
gun. The screw is pivoted in the left trail and moves in and out 
through a bushing pivoted in the right trail when the trails are being 
spread or closed. When the trails are to be closed, the gun is trav- 
ersed to the extreme right. 

The elevating mechanism is located on the frame in front of the 
traversing mechanism. A screw fitting into a nut pivoted in the 
frame is raised and lowered by a handwheel attached to its upper end. 
Above the elevating handwheel is a hook engaging a pin fitted to 
the underside of the cradle, thus the rear end of gun is secured to 
the trail and the elevation accomplished when the cradle is mounted 
in the trunnion bearings. 

A conical sheet metal flash hider is secured to the muzzle of the 
gun. Some of these carriages are equipped with an armor plate 
shield, suitably reinforced by stiff eners. The shield consists of three 
plates hinged together, and is mainly employed to protect the gunners 
from shrapnel and flying fragments. 



55 

The gun is provided with a telescopic sight for use in direct fire 
and a quadrant sight for indirect or masked |ire, either of which is 
mounted on the left side of the gun and in a bracket which is part of 
the striker rod housing. 

The wheels are 37.75 inches in diameter and have steel tires 1.875 
inches in width. 

The ammunition is of the fixed type having a steel projectile weigh- 
ing 1.097 pounds containing high explosive, and detonated by a 
base percussion fuse. A complete round of ammunition weighs 1.47 
pounds and is composed of projectile, brass case, primer, and 
powder charge. 




^ 
r 



GUN AND PERSONNEL ON THE MARCH (AMMUNITION CART LEFT IN THE REAR). 

AMMUNITION CART FOR THE 37-MILLIMETER GUN. 

The 37-millimeter gun limber (of the machine gun ammunition 
wagon type) is essentially a frame resting on two shafts having a 
movable bolt and rear fittings by means of which it can be joined 
to the gun mount. 

The limber carries 14 ammunition boxes, each containing 16 car- 
tridges packed in a fiber packing strip. There are also provided 
2 wooden boxes for carrying spare parts, tools, accessories, etc. 



37-MILLIMETER 1-POUNDER GUN CARRIAGE MARK A, 
MODEL I (BETHLEHEM). 



The 1-pounder semiautomatic gun and carriage was primarily in- 
tended for landing purposes, but it has been used in trench warfare 
and to accompany infantry troops. This equipment is well adapted 
to the latter uses, due to the fact that its weight is such, as to permit 
it to be readily transported from place to place by man power. 

The gun is made of nickel steel, with the gun body and breech end 
being forged in one piece. The breech mechanism is of the Bethle- 
hem semiautomatic type in which the breech is opened, the case 
ejected, and the firing pin cocked on counterrecoil. The block is 
closed by a spring which is compressed during counterrecoil and 
held in that position by the extractor until tripped by the insertion 
of another round. 

The carriage is of the long recoil type and consists essentially of a 
cradle, pivot yoke, trail, wheels, and axle. The cradle supports the 
gun, forms a housing for the recoil mechanism, and is itself supported 
by trunnions bearing on the pivot yoke. The recoil mechanism is 
located above the gun and consists of a hydraulic cylinder and 
counterrecoil springs. No elevating and traversing mechanisms are 
provided as the laying can be readily accomplished by means of a 
shoulder guard and grip. 

Open sights are furnished and a bullet proof armor plate shield 
affords protection for the cannonneers. 

Fixed ammunition is used, and is packed for transportation in steel 
boxes containing 60 rounds each. A hand cart for carrying four boxes, 
240 rounds, is issued, the front and lid of this cart, being bullet proof. 

Weights, dimensions, and ballistics. 

Length of gun inches. . 68. 2 

Length of rifling do 61. 7 

Number of grooves 12 

Muzzle velocity feet per second . . 2, 100 

Maximum range yards. . 4, 100 

Weight of charge pounds. . . 16 

Weight of projectile do 1. 07 

Weight of complete round do . . -. . 1.5 

Weight of gun and breech mechanism do 173 

Breech block Vertical sliding, semiautomatic . . 

Recoil (constant) inches . . 10 

Weight of carriage in battery position pounds. . 800 

Range of elevation degrees. . 5 to +15 

Amount of traverse , do 45 

Width of track inches . . 35 

Line of sight Dependent. . 

Height of axis of bore inches . . 29 

Diameter of wheels do . 42 

(56) 



57 




58 




2.95-INCH VICKERS-MAXIM MOUNTAIN GUN 
MATERIEL. 



WITH PACK OUTFIT. 



The 2.95-inch Vickers-Maxim mountain gun materiel, is of Vickers 
design and American and British manufacture. This materiel is 
intended for transportation by pack animals; for this reason it is a 
light, compact weapon, separating very quickly and easily into four 
loads for packing. 

The cradle is carried as one load, the wheels and axles as another, 
the trail another, and the gun as the fourth. Four other pack animals 
carry the pioneer tools, blacksmith's tools, supply chest, and signal 
tools, respectively. Additional pack animals are employed to carry 
the ammunition for the battery. Suitable pack frames with all the 
necessary attachments are provided for holding the load compactly 
and in proper place on the animal. 

Weights, dimensions, and ballistics. 

Caliber . . .inches . . 2. 953 

Length of gun do 35. 85 

Weight of gun, including breech mechanism pounds . . 236 

Rifling uniform, 1 turn in 25 calibers, right -hand twist. 

Weight of projectile do 12$ 

Weight of powder charge ounces . . 8 

Muzzle velocity feet per second - - 920 

Maximum range .. yards . . 4, 825 

Length of recoil of gun inches . . 14 

Height of axis of gun above ground do 26 

Maximum angle of elevation degrees . . 27 

Maximum angle of depression '. do .... 10 

Amount of traverse of gun on carriage do .... 

Diameter of wheels inches . . 36 

Width of track do 32 

Weight of carriage only pounds . . 595 

Weight of gun and carriage do .... 830 

The gun barrel is a one-piece steel forging, cylindrical in form. 
On either side of the breech end two lugs are provided to which the 
piston rods are secured when the gun is mounted in the cradle. For- 
ward of these lugs is a finished surface of uniform diameter which 
constitutes a bearing for the gun. This surface is supplemented at 
the forward end of the gun by two collars of equal diameter, thereby 
insuring a firm bearing for the gun in the cradle, either in recoil or 
in battery. At the bottom of the barrel is a guide which slides in a 

(59) 



60 

corresponding groove in the cradle, thus keeping the gun in proper 
position and preventing it from turning when in action. 

The breech mechanism is of the interrupted-screw type. A handle 
which swings from left to right turns and swings the block clear with 




one motion. The firing pin is operated by means of a trigger which 
is pulled by the firing lanyard. A safety device is incorporated to 
prevent firing when the breech is not closed. The breech is equipped 
with an extractor which ejects the empty cartridge case after firing. 



61 



The recoil mechanism is of the hydrospring type. It is known as 
the short-recoil type in which the gun is permitted. a length of recoil 
upon the carriage, sufficient to diminish the movement of the carriage 
on the ground but not sufficient to render the carriage stable. To 





z 

3 
(5 



y 





retard the movement of the carriage on the ground the wheels are 
locked by means of " brake ropes/' which lock the wheels to the trail. 
Two buffer cylinders, one on each side of the gun, are bored in the 
cradle casting. They contain both the recoil and counterrecoil 
mechanism. The cylinders are connected at the rear by a by-pass 
which keeps the oil pressure equal in the two cylinders. Throttling 



62 



is obtained by grooves of varying width in the cylinder liners. The 
piston rods are attached to the gun by means of interrupted screws, 
which permit quick removal for transportation. 

The counterrecoil mechanism consists merely of springs wound 
around the piston rods, which are compressed on firing and which 
return the gun into battery. 




REAR VIEW OF CARRIAGE. 

The cradle is a bronze casting comprising three parallel cylinders. 
The central cylinder supports the gun from the breech to within a few 
inches of the muzzle. The other two, as before stated, accommodate 
the recoil mechanism. In place of trunnions there are two lugs 
underneath the cradle through which passes the cradle axis bolt, by 
means of which the cradle is secured to the trail. This bolt is pro- 
vided with a handle and suitable catch for quick removal when 
disassembling for packing. The cradle also carries the sight bracket 



63 

and has a plane surface on top, on which the gunner's quadrant may 
be used. 

The elevating gear consists of a quadrant with a worm wheel 
segment thereon operated through suitable gearing by a handwheel 
on the left side of the trail. A bolt for quick release of the elevating 



eye 
pi 5 fan lock. 




DETAILED VIEW OF GUN. 



mechanism from the cradle is provided. Elevations from 10 degrees 
depression to 27 degrees elevation may be obtained. 

No traversing mechanism is provided, and transverse must there- 
fore be obtained by swinging the trail. 



e/sra//** /breech 




SIDE VIEW OF CARRIAGE IN BATTERY. 

The trail consists of two steel side plates connected by crosspieces 
and transoms. The front crosspiece contains bearings for the axle, 
cradle axis bolt, and elevating gear. A shoe at the rear end of the 
trail is fitted with a "scraper," which in reality is a short spade. It 
is also provided with a socket for the handspike. 
18322820 5 



64 

The axle is a solid cylindrical bar with flats cut on two sides for 
securing it in the front crosspiece of the trail. It is quickly removable 
for packing and is carried on the same pack animal as the wheels. 
The wheels are 36 inches in diameter and are steel tired. 

Sighting is accomplished by means of the sight, model of 1912, 
combined with either an open sight or the panoramic sight. 

The sight shank is a steel arc which can be moved up and down in 
elevation by means of a scroll gear. A range strip on the rear face of 
the arc is graduated in 50-yard divisions up to the maximum range 
of the piece. 

Combined with the sight is a graduated level which serves the same 
purpose as the range quadrant used on the 3-inch equipment and other 
materiel of that type. By this means the piece is laid for elevation. 

The sight is mounted on the left side of the cradle. By ha\ ing the 
quadrant level and sight thus combined one man can lay for both 
elevation and direction. 

The ammunition used is of the fixed type, consisting of the steel 
high explosive and shrapnel shells, each weighing 12 J pounds. Each 
animal carries two chests containing five rounds each. 



75-MILLIMETER GUN MATERIEL, MODEL 1916. 



The United States model 1916, 75-millimeter field gun is an adap- 
tation from the United States 3-inch field gun, model 1916, arranged 
with a split trail and having greater traverse and greater elevation 
than either the French or British models of this caliber. 

The 75-millimeter field gun constitutes the light artillery or rapid 
mobile field artillery of the Army. The caliber of the piece is about 
as large as ready horse-drawn mobility will permit. The caliber is 




FRONT VIEW OF CARRIAGE. 

equivalent to 2.95 inches, and was adopted by the French and by 
the Italians, while the United States had adopted the caliber of 
3-inch and Great Britain a caliber of 3.3-inch, which is the caliber of 
their 18-pounder. The German caliber was 77 millimeters, equivalent 
to 3.03 inches. The points of excellence obtained from these types 
are accuracy, long range, rapidity of fire, ease of transportation, and 
smooth and reliable functioning. 

As the range depends not only on the power of the gun and on the 
design of the ammunition but on the elevation provided for, and 

(65) 



66 




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LJ 
O 

2 CD 

cr 02 
ok 



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68 

as the horizontal afc which could be covered by a gun with a single 
setting of its trail is governed by the permissible traverse, great 
attention was given to the mechanical features covering the vertical 
and horizontal limits of the gun laying, as well as to the smooth and 
reliable functioning of the piece. Of the above models, the French 
model is credited with functioning most perfectly, but the United 
States completed a new carriage which permits very high elevation 
of the gun and wide traverse. Due to the permissible elevation, the 
American piece outranges the French, although the French gun has a 
greater muzzle velocity. 

Roughly, the weight of the piece, including the carriage and limber, 
is about 4,600 pounds, which in general corresponds with the horse- 
drawn draft limitation over rough ground of 765 pounds per animal, 




REAR VIEW OF CARRIAGE 



calling for six horses to the piece, although four horses are frequently 
employed over level or hard ground. 

The introduction of motor tractors has altered the draft problem, 
but there still remains the question of facility in handling the piece 
by man power after battery position has been reached. As illus- 
trative of this it may be mentioned that the weight at the end of a 
75-millimeter gun carriage trail is in the vicinity of only 100 pounds. 
The trails can be readily unlimbered and spaded into position or its 
position changed by man power within a few moments, while to 
unlimber and spade into position or to change the position of the 
trail of a 155-millimeter gun requires the use of jacks and a con- 
siderable expenditure of time. 

Rapidity in moving a fieldpiece from point to point, where railroad 
transportation is not available, is not entirely a matter of the speed 
of the tractor, for likelihood 6f damage to the materiel when trans- 
ported at high speed on its own wheels must also be considered. 



69 



The dimensions and weight of the 75-millimeter piece permit of its 
being placed on a rubber-tired trailer, which allows of its being 
transported at high speed behind a motor vehicle. 

The movement of the light artillery is of utmost importance, and the 
75-millimeter field gun may be considered as a gun of first rank, for 
it constituted the light artillery of the military powers. This weapon 
is accurate, has a range up to 6 or 7 miles, is suitable for the projection 
of high explosives, shrapnel, incendiary, smoke, asphyxiating, tear, 
tracer, illuminating, terrorizing, and chain projectiles, and is adaptable 
for barrage fire, destruction of personnel, tearing away of wire entangle- 
ments, destruction of fair-sized obstacles, and to some extent the 
destruction or protection of lines of communication. The indications 
are that a slightly larger caliber will supplant this caliber in order to 
obtain longer range and greater destructive force and either motoriza- 
tion or direct mounting on self-propelled caterpillars may affect the 




LEFT SIDE VIEW OF CARRIAGE. 



adoption of a new caliber, for mobility and rapidity and ease of 
handling are features of importance in this branch of the field artillery. 

Weights, dimensions, and 'ballistics. 

Weight of gun and breech mechanism pounds. . '< -19 

Length of gun inches. . 90. 9 

Caliber millimeters. . 75 

Length of bore inches. . 84 

Length, calibers 28 

Rifling, right hand twist, zero turns from origin to point 2.89 inches from 
origin; from this point increases one turn in 119 calibers to one turn in 25.4 
calibers at a point 9.72 inches from muzzle. Uniform from this point to end 
of muzzle. 

Number of grooves 

Muzzle velocity: 

Shrapnel feet per second . . 1, 

Shell (short fuze) .do 1, 



24 

693 
900 



Shell (long fuze) do. ... 1, 876 



70 

Maximum range: 

Shrapnel (Mark IV shell) yards. . 9, 650 

Shell (short fuze) '.do 12, 360 

Shell (long fuze) , do. ... 11, 155 

Weight of carriage, complete (without gun) pounds . . 2, 280 

Weight of gun and carriage, fully equipped do 3. 045 

Diameter of wheels inches. . 56 

Width of track do 60 

Length of recoil of gun on carriage (variable) do .... 18-46 

Height of axis from ground do. ... 41. 625 

Maximum angle of elevation degrees. . 53 

Maximum angle of depression do 7 

Maximum traverse, each side of center mils . . 400 

Maximum angle of elevation with angle of site handwheel. . .. degrees. . 11 

Maximum angle of depression with angle of site handwheel do. ... 7 



75-MILLIMETER GUN AND CARRIAGE, MODEL OF 1916 

(AMERICAN). 



The gun is of the built-up construction and consists of a tube, 
jacket, locking hoop, breech hoop, and clip. There are six slightly 
varying types of this gun, but the variations deal only with the 
manner of attachment of the jacket and locking hoop and do not 
affect the general dimensions. The gun is guided in recoil by two 
flanges on the lower sido of the jacket. A lug on top near the for- 
ward end of the jacket containing a T-slot, holds the forward end of 
the recoil cylinder. 

A short hoop or clip is shrunk on the tube near the muzzle and has 
on its under side two lugs which form guides for the gun on the 
cradle. Provision has been made to prevent dust from entering be- 
tween the surfaces of the guides and their bearing surfaces on the 
cradle. 

The breech ring, which screws to the rear end of the jacket, forms 
a housing for the breech block which slides up and down with the 
action of a wedge. The ring carries at the top a lug to which the 
hydraulic recoil cylinder is secured, and at the bottom another to 
which the two spring piston rods are attached. 

The breech block is of the drop-block type and operates semi- 
automatically, in that the breech closes automatically when a round 
of ammunition is inserted, it is opened by pulling back a handle on 
the right side of the breech, which not only slides the breech block 
out of place but operates the extractor, thus ejecting the empty car- 
tridge case. When a round is inserted smartly into the breech, its 
rim strikes against the lips of the extractor causing the mechanism to 
close under the action of the closing spring. The cartridge primer is 
fired from the left side of the carriage by a continuous-pull firing 
mechanism. The firing pin is cocked and fired by one continuous 
backward motion of the firing handle. 

The carriage is of the split-trail type which means that the trail is 
made up of two halves, each being hinged to the axle near the wheels 
and capable of being spread out at a wide angle or brought together 
at the spade ends and locked for traveling. This feature permits 
greater elevation and traverse than the ordinary type of trail and 
reduces the necessity of shifting the trail when changes in deflection 
of 50 mils or more are desired. 

A seat is provided on each half of the trail, the one on the left for 
the gunner who operates the sights, the traversing and angle of site 
handwheels, and fires the piece, and the one on the right for a can- 
noneer who sets off the range and angle of site and operates the 
breech mechanism. 

(71) 



73 




I SSi 



74 

The recoil mechanism is of the hydro-spring variable recoil type 
consisting of one hydraulic and two spring cylinders which comprise 
the recoil and counterrecoil mechanisms. On account of the high 
angles of elevation at which this gun can be fired, it was necessary 
to design a variable recoil system by means of which the length of 
recoil of the gun would be automatically lessened, the higher the 
muzzle is elevated. This is accomplished by means of a valve turn- 
ing in the cylinder and shutting off or opening a number of holes, 
proportional to the elevation, thus making the resistance to the 
passage of the oil greater or less. 




GUN AT MAXIMUM ELEVATION. 

The angle of sight mechanism consists principally of a rocker 
which is moved by two hand wheels, one on each side of the gun. 
Movement of the mechanism causes the gun, cradle, elevating mech- 
anism, and sights to move also, they being connected to the rocker. 
The handwheel on the left or gunner's side is used when laying for 
direct fire, or in other words, when site is set independent of range. 
The angle of sight scale is graduated in mils. All settings on the 
angle of sight scale are set oft' above or below the 300-mil graduation, 
this being the normal setting when the axis of the bore and the 
target are in the same horizontal plane. 

The elevating mechanism used in setting the range is mounted on 
the rocker, and therefore independent of the angle of sight mechanism? 
the gun and cradle only being moved upon operation of the hand- 
wheel. The range scale is graduated in meters. 

Band brakes are used on this carriage and are operated by a hand 
lever in rear of the shield when in battery position and by a lever 
from the axle seat when in traveling position. 



75 




76 

The gunner and cannoneers are protected by the customary shields 
and apron. 

The sight used is of the model of 1916 type, which provides a sup- 
port for the panoramic sight and the peep sight. 

Wooden wheels, 56 inches in diameter, with steel hubs and tires, are 
used, the tires being 3 inches in width. These wheels are interchange- 
able with those of the caissons and limbers. 

Fixed ammunition is used in the 75-millimeter field guns and is made 
up of either common shrapnel or common steel shell. Shrapnel 
rounds are issued with the projectiles filled and fuzed; the shell 
rounds are issued filled but not fuzed and contain an adapter with 
booster charge. 

The projectiles average in weight: Shrapnel, 16 pounds, fuzed; 
shell, 12.3 pounds, fuzed. The components of one round are the 
cartridge case with primer, powder charge, projectile, and fuze in 
shrapn.el, and adapter and booster in the shell. Weight of powder 
charge is approximately 1.5 pounds. 




CARRIAGE AND LIMBER IN TRAVELING POSITION. 

A battery of 75-millimeter gun carriages, model of 1916, is accom- 
panied by the following vehicles : 

75-millimeter gun carriage limber, model of 1918. 

75-millimeter gun caisson, model of 1918. 

75-millimeter gun caisson limber, model of 1918. 

Forge limber, model of 1902 Ml. 

Store limber, model of 1902 Ml. 

Battery and store wagon, model of 1917. 

Battery reel, model of 1917. * 

Reel, model of 1909 Ml. 

Cart, model of 1918. 1 

The above gun carriage was originally the 3-inch gun carriage, 
model of 1913, which was later called the 3-inch gun carriage, model 
of 1916. The gun was afterwards modified to caliber 75 millimeters, 
as was the 3.3-inch British, thereby permitting interchangeability of 
ammunition with the French guns. 

1 For horse batteries the battery reel, model of 1917, is issued. For motorized batteries the reel, model 
of 1909 Ml with the cart, model of 1918, is issued in lieu of the battery reel, model of 1917. 



77 



INTERMEDIATE SHAFT GEARr ~ 
v-.5xLB370|)STUD. ^575* L9l2(lf)Srua. 
\5CROWN NUT=r\\ /T-375 CROWN C 



TRAVERSING STOP y 

.093(&J< I.B75STEEL VMS' 
TRAVERSING I 

AZIMUTH SCALE.'' . ^. . 

AZIMUTH POINTER.^/ ..5CROWNNUTJAPPED.625STai 
^~^9bT375STb7c3UNKHEAD GERMAN SILVER SCREWS^ 

INSTRUCTION PLATE (TRAVERSING). ^""""" CRANK PIN;- 

.625 CROWN NUT.^ CRANt^LEEVC-^*^' 

^-^^ -v 




_-- -ANGLE OF SITE BRACKET COVER(LCFT) 
^TraWtRSNG HANOWHECl. SHAFT. 



-*" i iffTS * ...u/ vv ww.. 

~>- ANGLE OF SITE BPACKET(LEFT) 
-^575 HANDY OILER. 

-HUB. 
,^HANDWHEEL BODY. 

^*** / 



.375 HANDY OILER 



BRONZE PLUG.' 




.375x I.3I20|)BOLTS. =mniZ 
TRAVERSING INTERMEDIATE SHAFT. -j 



INTERMEDIATE SHAFT BEARING. 7 



_ --TRAVERSING WORM SHAFT BEARING. 

"^^,-is.x i.8i20g) srua 

'"^^-* CROWN NUT. 

TRAVERSING WORM SHAFT. 

-TRAVERSING WORM (HINDLEY.) 



' 



X 



^^ -TOP CARRIAGE. 

-HALF BUSH I NG^75x".T5 fTOP CARRIAGE.) 



\ \\\ " 

.125 x. 75 STEEL PIN A \ \ S> ADJUSTING NUT. 

WASHEP.A ^-.125 X 1.75 SPLIT PIN 



75 M M.GUN CARRIAGE. MODEL OF 1916. 

TRAVERSING MECHANISM. 



75-MILLIMETER GUN MATERIEL, MODEL OF 1916 MI. 

There will soon be issued to the service a number of model 1916 
75-millimeter gun carriages, redesigned to mount a St. Chamoiid 
hydropneumatic recoil mechanism in place of the hydrospring type, 
and a standard 75-millimeter gun modified and fitted with a counter- 
weight. The new materiel will be known as the 75-millimeter gun 
materiel, model of 1916 ML 

The St. Chamond recoil mechanism as adopted for these carriages 
was developed during the war in 1917 by Col. Rimailho, of the French 
Army. This mechanism, of the hydropneumatic type, is durable and 
smooth in operation. The use of small cradle forgings was made 
possible by the introduction of high pressures in the recuperator and 
recoil cylinders. In order to hold these pressures, it was necessary 
to develop suitable packing, and the success of this recoil system is 
largely due to the design of these packings. 

The St. Chamond recoil mechanism consists of three cylinders, the 
middle one being the recoil cylinder, the right cylinder having an air 
reservoir at its forward end, and an oil reservoir at its rear end; the 
left cylinder, known as the recuperator cylinder, has at its forward 
end an air space, and at its rear end a floating piston and regulator 
for controlling the length of recoil. 

The recoiling parts are held in battery by the reaction of the air on 
the floating piston transmitted through the liquid against a leak- 
tight recoil piston. In recoil the gun moves to the rear, carrying with 
it the recoil piston (middle cylinder) . The energy of recoil is absorbed 
by the throttling of the oil through a spring-controlled orifice in the 
regulator valve. 

An opening is provided between the recoil and the recuperator 
cylinders to house the regulator valve. During recoil, the pressure in 
the recoil cylinder opens the regulator valve, the movement of which 
is controlled by a helical spring and Belleville springs. The oil pass- 
ing through the orifice controlled by this valve moves the floating 
piston forward against the air pressure, thereby storing up energy to 
return the gun from the recoiled position to its position in battery. 
The valve in the counterrecoil orifice remains closed during recoil. 

The throttling during recoil is controlled by the regulator valve ? 
which consists of two parts, an upper stem and a lower valve stem. 
The lower valve stem is seated on a circular seat at the entrance 
channel to the valve. As the valve lifts, the throttling area becomes 

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79 

the Vertical circumferential area between the valve and its seat. In 
long recoil the movement of the valve is controlled by a spiral spring 
which reacts on the lower valve stem. The upper stem rests in a valve 
housing and has Belleville springs reacting on the stem only. To 
move the upper valve stem, the whole housing is lowered automatic- 
ally by a cam operated by the elevation of the cradle. At short recoil, 
the upper stem of the regulator is brought down by the cam until its 
lower surface is in contact with the top surface of the lower valve 
stem in order to control the throttling of the valve. 

The regulator valve is closed during the counterrecoil movement. 
The oil flow during counterrecoil is different from that during recoil, 
the counterrecoil flow path being through a small channel beginning 
at the inside end of the buffer chamber in the recuperator cylinder 
and finally emptying into the recoil cylinder. The throttling during 
counterrecoil takes place through a constant orifice located at the 
beginning of the counterrecoil channel. The tapering buffer rod on 
the floating piston in the recuperator causes additional throttling 
through the small annular area between the buffer chamber and buffer 
rod of the floating piston, which brings the recoiling parts to rest 
without shock. 

18322820- 6 



75-MILLIMETER GUN MATERIEL MODEL OF 1897 Ml 

(FRENCH). 



The -French 75-millimeter field gun adopted for the service of the 
United States dates back to 1897, when it was perfected by the 
French Army. 

The French model 1897 field gun has fired, on test, as high as 30 
shots in a minute, and it is understood that the American model 
1916 equaled this rate; likewise, a St. Chamond gun with interrupted 
screw-type breech on the special St. Chamond recuperator. Apart 
from the personnel service to the piece, the length of time which either 
gun could maintain this rate of fire, or any other rapid rate of fire, 
is perhaps not definitely determined. As to whether or not such 
length of time would be limited by the heating of the gun or by the 
heating of the recoil mechanism is likewise perhaps not definitely 
determined. 

Rapidity of firing is of vital importance, for it is self-evident that 
under certain conditions a gun which can fire twice as many shots 
per minute as some other gun is, for the moment, equivalent to two 
guns of the second class. Rapidity of firing action is dependent 
upon the arrangements involved for the sighting, maintaining of the 
gun on its range, loading, firing, time of recoil and return of the gun 
to battery position, opening of the breech, and ejection of the empty 
cartridge case. 

For artillery of position a great part of the enormous energy re- 
quired to start the projectile on its way may be absorbed by a heavy 
foundation furnished as a mounting for the piece. An efficient recoil 
mechanism is, however, of vital importance in connection with light 
artillery for field service, owing to the essentially light weight of the 
carriage on which the gun is mounted, to permit of its ready mobility. 

The recoil mechanism not only absorbs the greater part of the 
recoil energy of the gun, but it returns the gun to the battery or fir- 
ing position, and to be efficient it must be able to perform these two 
functions quickly, smoothly, surely, and continuously. The word 
" surely" is used in the sense of firmly and without shock, and of 
being reliable. The recoil mechanism not only takes up the recoil 
but it forces the gun all the way back into battery, or to a position 
within the variation which the design permits, under all conditions 
of elevation and heating. 

The general theory of hydropneumatic recoil mechanism is not 
new. In its relation to light artillery its most notable exemplifica- 
tion in battle has appeared in the Puteaux Arsenal type of the French 
piece. Its virtues have been widely heralded and every effort has 
been made to keep its construction secret. Its several parts were 

(80) 



81 




32 




83 

manufactured at different points in France and these were assem- 
bled in a small room at the Puteaux Arsenal, and but few persons 
were admitted to this room. In the agreement, to manufacture of 
the complete recuperator in the United States, it was stipulated that 
the greatest secrecy should be maintained with reference to its de- 
sign, manufacture, and assembly. 

There is a difference between land and naval warfare, in this 
respect: In a duel between two large fighting ships of equal speed 
to insure their remaining in contact, the one with the heavy, long- 
range guns has the other at its mercy, as it can destroy both its oppo- 
nent's base and at the same time its opponent's personnel by sinking 
the opponent ship. In a land battle, the fortifications may be re- 
duced by the long-range gun, of heavy caliber, but it is the destruc- 
tion or capture of personnel which brings a war to an issue and the 
personnel may move to open country and open order, under which 
conditions the heavy, long-range gun, which is expensive to construct, 
slow and difficult to transport, expensive to fire, and withal short of 
life, no longer has a great target on which its tremendous energy may 
be concentrated. 

Land warfare has clearly demonstrated that it is the killing and 
disabling of personnel or the capture of enemy troops in large num- 
bers which far outweighs the capture of cities or of terrain which 
is nonproductive of raw material, in the forcing of an issue. This 
75-millimeter gun was most effective in the open-country fighting, in 
the protection of troops and in working havoc among enemy troops 
and bringing in prisoners by creeping barrage laid behind an enemy 
formation. 

Weights, dimensions, and ballistics. 

Caliber millimeters. . 75 

Total weight of gun and breech mechanism pounds.. 1,015 

Total length of gun inches.. 107. 125 

Rifling, uniform, right hand, 1 turn in 25.6 calibers. 
Muzzle velocity: 

Shell (short fuze) feet per second. . 1, 955 

Shell (long fuze) do 1, 930 

Shrapnel do. ... 1, 755 

Maximum range: 

Shell (short fuze) (Mark IV shell) yards. . 8, 640 

Shell (long fuze) do 9, 350 

Shrapnel do 7,440 

Weight of complete round of ammunition: 

Shrapnel ; pounds. . 16 

Shell .do .... 12. 3 

Diameter of steel tired wheels inches. . 52. 5 

Width of track do 59. 68 

Length of recoil of gun on carriage do .... 44. 9 

Height of axis of gun from ground do 40. 4 

Maximum angle of elevation degrees. . 19 

Maximum angle of depression do 10 

Total traverse of carriage on axle do ... 6 

Weight of the carriage, complete (without gun) pounds. . 1, 642 

Weight of gun and carriage, fully equipped do. . 2, 657 



84 




85 




86 

75-MILLIMETER GUN AND CARRIAGE, MODEL OF 1897, Ml (FRENCH). 

The gun is of the built-up construction type, consisting mainly of 
a steel tube reinforced at the breech end with a breech hoop and 
covered in the central portion with a bronze jacket. The total 
length from face of breech to muzzle is slightly less than nine feet. 

The recoil lug under the breech carries the coupling key, which 
connects the gun to the recoil mechanism. A safety pin operates 
between the breechblock and the coupling key, so that it is impossible 
to close the breech and fire the gun when it is not securely locked 
to the recoil mechanism of the carriage. 

On the underside of the gun are inclined bronze slides which are 
in contact with similar slides on the recoil mechanism. Rollers 
are also attached to the gun, and during recoil the gun first slides on 
the inclined guides and then the rollers lift the weight off the slides, 
the remainder of the travel being on the rollers. A pair of rollers 
at the muzzle permit a long recoil with short guides by taking the 
overhanging weight when the gun is at full recoil. 

The 'breechblock is of the Nordenfeld type, cylindrical in shape and 
threaded on the outside. It is opened or closed by the operating 
handle from the right side of the gun by the same man who sets the 
gun for range and fires the piece. Opening the breech' automatically 
actuates the extractor, which in turn ejects the empty cartridge case. 
The round of ammunition is fired by a striker which is driven for- 
ward by a spring-actuated hammer pulled by the lanyard. 

The carriage is very compact and simple, consisting of a housing 
around the axle, above which is the support for the cradle, and a 
box section trail ending with the customary spade and lunette 
Seats are provided for two men, the one sitting on the right side 
operating the range scale mechanism, opening or closing the breech 
and firing the piece; the man on the left sighting the gun and oper- 
ating the angle of site and traversing mechanisms. 

The reccil mechanism is of the hydropneumatic, long recoil type 
and contains both recoil and counterrecoil mechanisms. A gage 
plunger is located in the rear end of the cradle which, when flush, 
indicates that more oil should be added until the plunger projects 
about f inch. Oil may be added by forcing it through a valve in the 
side of the cradle by a hand screw filler, or by means of a portable 
battery pump clamped to the side of the trail and connected through 
the trunnions to the interior of the cradle. 

The recoil mechanism is housed inside of the cradle, through which 
are bored an upper and lower cylinder, filled with Oleonapthe, able 
to communicate together by means of a passage provided for that 
purpose. The front part of the upper cylinder (in front of the 
piston) is permitted to communicate freely with the air through a 



87 




88 



if 

1 

Mil? 




89 

plug, but the forward end of the lower cylinder is closed and con- 
tains compressed air at approximately 150 kilograms per square 
centimeter (1,833.5 pounds per square inch). 

In the upper cylinder a piston is permitted to move, the piston 
rod, however, being secured to the gun. The lower cylinder is 
fitted with a pipe, at the end of which is a circular ring, this pipe 
being screwed in the rear part of the cylinder where the valves are 
housed. A diaphragm equipped with a hollow rod, also a floating 
piston fitted with a small rod, a/re incorporated in the low r er cylinder. 

During recoil the piston of the upper cylinder compresses the 
liquid, forcing it to pass through various valves, also openings 
formed between the pipe and the hollow rod of the diaphragm. The 
passing of the liquid through these different openings constitutes the 




LEFT SIDE VIEW OF CARRIAGE. 



braking, in so moving, the liquid opens the valves (which are widely 
opened at the beginning of the recoil and gradually close in propor- 
tion to the decrease of the speed of the recoil). At the same time, 
the air in the lower cylinder is compressed by the action of the 
liquid on the diaphragm. To return to battery at the end of the 
recoil, the compressed air forces the diaphragm back. The liquid 
thus compressed acts directly on ,the upper cylinder piston, causing 
it to return to its initial position. 

The interior of the recoil mechanism was maintained confidential 
by the French Government before and during the war, and when its 
manufacture was taken over by the Ordnance Department, agree- 
ment was made to continue the secrecy of these parts. Very fine 
adjustments are made when the parts are assembled, and conse- 
quently no repairs or adjustments are permitted to be made in the 
field. The complete recoil mechanism must be sent to special 



90 

repair depots. The recoil mechanism will function properly without 
the operating personnel understanding the interior mechanism. 

The angle of site mechanism consists of a handwheel and gears, 
and provides for elevating or depressing a rocker 13 degrees with 
reference to the trail. The rocker fits around the trunnions and 
has a segment of a gear which meshes with the elevating pinion. 
To the rocker is secured an elevating screw and nut which connects 
with the cradle. In setting the angle of site, the rocker is set in 
motion, thereby moving the cradle and gun. 

The range scale mechanism which operates the elevating screw 
provides an elevation of 12 degrees to give the correct range and is 
obtained by movement of the cradle in reference to the rocker. 

The circular scale graduated in meters indicating the range, is 
mounted on the side of the cradle and through gearing is connected 
to the elevating screw. A range rack is connected to the rocker 
arm which is also graduated in meters. On carriages made in 
America an extra strip is placed alongside the range rack and is 
graduated in mils. The range scales are graduated up to 5,500 
meters, but greater ranges can be obtained by burying the trail, 
and thus giving higher angles of elevation. Interference of the 
breech against the trail, however, limits the total possible elevation 
obtainable by combination of the elevation due to the angle of site 
and due to range to 19 degrees. 

On this carriage axle traverse is used. A geared nut, held inside 
of the axle housing, rotates around the axle which is threaded with 
a coarse rectangular thread. Movement of this nut forces the 
carriage to the right or left, pivoting around the spade, one wheel 
advancing and the other backing up. Traverse is about three 
degrees right and three degrees left. 

A combination road brake and firing support is hung around the 
axle, permitting the application of brake shoes against the tires 
of the wheels when traveling, and the lowering of the framework to 
the ground and mounting the wheels thereon, for firing. This last 
operation is called abatage, the three steps being indicated in the 
following figures: 






POSITION I POSITION Z POSITION 3 

ABATAGE POSITION 

Wooden wheels, 1,334 millimeters (52.5 inches) diameter, are used, 
and have steel tires 3.5 inches wide. These wheels are interchange- 
able with the French limber wheels, but not with the American 
limber or caissons for the 75-millimeter gun carriages. 



91 




92 




93 

The customary shield and apron protects the gunners when 
under fire. 

The angle of site mechanism is also called the independent line 
of sight, because the range setting is independent of the setting of 
the angle of sight, which is done by the angle of sight handwheel. 
% The sight, model of 1901 (French), includes the collimating sight, 
angle of site level, and angle of site scale. It is mounted on the 
left side of the rocker, at the trunnions. It has no telescopic features 
and, therefore, its range is limited. An auxiliary angle of site level 
is furnished to replace the regular level and gives an additional 200 
mils for use in the hilly or mountainous country. 

Fixed ammunition is used in this 75-millimeter field gun and is 
made up with either common shrapnel or common steel shell. 
Shrapnel rounds are issued with the projectiles filled and fuzed; the 
shell rounds are issued filled but not fuzed, and contain an adapter 
with booster charge. 

The projectiles average in weight: Shrapnel, 16 pounds, fuzed; 
shell, 12.3 pounds, fuzed. The components of one round are the 
cartridge case, with primer; the powder charge; projectile; and fuze, 
in shrapnel; and adapter and booster in the shell. 

75-MILLIMETER GUN MATERIEL, MODEL OF 1897M1 (FRENCH) 

A battery of 75-millimeter gun carriages, model ol 1897M1 (French) 
is accompanied by the following vehicles: 

75-millimeter gun and carriage, model of 1897M1. 

75-millimeter gun carriage limber, model of 1918. 

75-millimeter gun caisson, model of 1918. 

75-millimeter gun caisson limber, model of 1918. 

Battery and store wagon, model ol 1917. 

Forge limber, model of 1902M1. 

Store limber,. model of 1902M.1. 

Battery reel, model of 1917. 1 

Reel, model of 1909M1. 1 

Cart, model of 1918. 1 

The gun and carriage are of the French design, and of both French 
and American manufacture. The accompanying vehicles are all of 
American design and manufacture. 



1 For horse batteries the battery reel, model of 1917, is issued. For motorized batteries, the reel, model 
of 1909 Ml, with the cart, model of 1918, is issued in lieu of the battery reel, model of 1917. 



75-MILLIMETER GUN MATERIEL, MODEL OF 1917 

(BRITISH). 



The 75-millimeter gun, model of 1917 (British), was originally 
known as the 18-pounder, but was modified by adapting it to the 
75-millimeter caliber materiel. This weapon is equipped with cus- 
tomary unit trail; the interference of the trail with the breech limits 
the gun elevation. With the split trail, the breech can pass down 
into the V formed by separating the two sections of the trail. The 
theoretical elevation for obtaining maximum range under ideal bal- 
listic conditions is 45 from the horizontal, and is actuallv some few 




FRONT VIEW OF CARRIAGE. 



degrees less than this. Increased range is sometimes obtained with 
field guns whose normal elevation is limited by setting the axles or 
wheels on raised surfaces, or by sinking the trail below the level of 
the wheels, for the purpose of pointing the gun at an elevation higher 
than the mechanical arrangement of the carriage permits. This is, 
however, a subterfuge, limited in its practical application. 

The American model 1916 split-trail carriage permits great eleva- 
tion within the mechanism of the carriage and likewise a wide 
traverse without changing the position of the trail. The recoil 
mechanism on the 1916 model was adapted to the higher permissible 
elevation of the gun, and was supplied with a variable recoil, auto- 
matically adjusted to different elevations. The ability to outrange 

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18322820 7 



96 




97 

the enemy is an attainment constantly being sought, and therefore 
high elevation and reduction of resistance of the projectile passing 
through air are the means through which it was hoped to obtain the 
increased range desired. Likewise, a wide horizontal arc of fire, 
without resetting of the trail and consequent resetting of the sight- 
ing devices, is a great convenience and saver of time. 

As compared with the British model 1917, the American 3-inch 
model of 1902 carriage permits of a maximum angle of elevation of 
15, depression of 5, and traverse of 142 mils, while the British 
model permits 16 elevation, 5 depression, and 142 mils traverse. 
The French model 1897 carriage permits a maximum angle of eleva- 




REAR VIEW OF CARRIAGE. 



tion of 19, depression 10, and traverse 106 mils. The American 
model 1916 carriage allows a total vertical movement of from 53 
elevation to 7 depression, and a traverse of 800 mils (an artillery 
mil equals the angle of - 6 -4W f a circumference). The American 
model 1902 carriages are arranged with an hydro-spring recoil mech- 
anism, and so is the British model 1917 and the American model 
1916. The French model 1897 carriage is equipped with an hydro- 
pneumatic recoil mechanism. 

The basic difference of the recuperator or recoil mechanism of the 
French model 1897 gun, as compared with the British model and the 
American model, lies in the fact that the French model involved the 
principle of oil and compressed air for absorbing the recoil of the gun 



98 

and returning it to battery or firing position, and is practically self- 
contained in one large heat-treated steel forging, with a system of 
finely fitted surfaces and adjustment valves. In the British and 
American model recoil mechanism, oil and steel springs, instead of 
compressed air, are employed, with a combination of pistons and 
steel tubing. 

A reference may also be made relative to the desirability of single 
or unit trails as compared with the split trail. The latter allows of 
greater traverse, but as a new objective makes necessary a resetting 
of the trail, the change in setting requires much more time than with 
the unit trail. The split trail is heavier and the equalizing mecha- 
nism, necessary to the proper distribution of recoil shock to both trail 
sections, establishes a relative movement between the two trail sec- 
tions, with the result that the split trail can be set up less quickly 
than the unit trail on uneven ground. 

Weights, dimensions, and ballistics. 

Caliber millimeters. . 75 

Weight of gun and breech mechanism pounds. . 995 

Total length of gun inches. . 88. 21 

Length of bore do. ... 83. 915 

Rifling, right-hand twist, zero turns at origin to 1 turn in 75 inches at 9.72 
inches from muzzle, thence uniform. 

Number of grooves 24 

Muzzle velocity: 

Shrapnel feet per second. . 1, 693 

Shell (short fuse) do. ... 1, 900 

Shell (long fuse) do. ... 1, 876 

Maximum range: 

Shrapnel (Mark IV shell) yards. . 6, 464 

Shell (short fuse) do.... 8,100 

Shell (long fuse) do. ... 7, 450 

Weight of one round of ammunition: 

Shrapnel pounds. . 16 

Shell do. ... 12. 3 

Weight of carriage, complete f without gun) do 1. ; .*> 

Weight of gun and carriage, fully equipped do 2, 945 

Weight of gun and carriage in battery position do 2, 860 

Diameter of wheels inches . . 56 

Width of track do .... 60 

Length of recoil of gun on carriage do 49 

Height of axis from ground do 38. 86 

Maximum angle of elevation degrees . . 16 

Maximum angle of depression do 5 

Maximum traverse, each side of center mils . . 72 

Weight of gun, carriage, and limber (British) fully equipped, also loaded 

with shrapnel and fuze boxes pounds . . 4, 591 

Weight of gun, carriage and limber (American) fully equipped, also loaded 

with shrapnel and fuze boxes pounds. . 4, 458 



99 




100 

75-MILLIMETER GUN AND CARRIAGE, MODEL OF 1917 (BRITISH.) 

The gun is built up of alloy steel, consisting of a tube, a series of 
layers of steel wire, jacket, and breech ring. The tube extends 
from the rear end of the chamber to the muzzle. Over the rear por- 
tion of the tube are wound 15 layers of steel wire. The jacket is 
fitted over the exterior of the tube and wire, and is secured longitu- 
dinally by corresponding shoulders and the breech ring, which is 
screwed over the jacket at the rear and secured by a set screw. The 
breech ring is prepared for the reception of the breech mechanism, 
and is provided on the upper side with a lug for the attachment of 
the hydraulic buffer. Longitudinal projections on each side of the 
jacket form guides for the gun when in the cradle of the carriage. 
A plane for a clinometer is prepared on the upper surface of the breech 
ring. Vertical and horizontal axis lines are cut on the face of the 
muzzle for use in verifying the adjustments of the sight. 

The breech block is of the interrupted screw type having two threaded 
and two slotted sectors. The breech recess of the gun is slotted 
and threaded to correspond with the threads on the block and the 
latter is screwed to a cylindrical section, or carrier, which is hinged 
to the right side of the breech. Hinged to the rear face of the carrier 
is a hand lever, provided with bevel teeth which engage with corre- 
sponding teeth on the rear face of the breech block, so arranged that 
when the lever is pulled to the right, the first movement of the lever 
unlocks the breech block, and on continuing the motion the block 
and carrier are swung into the loading position. The breech is 
opened by the cannoneer on the right seat pulling the hand lever 
toward him. The extractor, hinged to the right side of the breech, 
is automatically actuated in opening the breech, thus ejecting the 
empty cartridge case. 

The firing mechanism is so arranged that the gun can not be fired 
before the breechblock is home and the hand lever locked and is 
known as a continuous-pull mechanism. By means of the firing 
lever on the left side of the gun, operated by the gunner, the firing 
pin which seats in an axially bored hole in the breechblock, is cocked 
and fired by one continuous backward motion of the lever. 

The carriage has a tubular steel trail and axle, the rear end of the 
trail being fitted with a spade, lifting handles, trail eye, and traversing 
lever. The top carriage is provided with bearings, by means of which 
it is pivoted on the axle for traversing. Bearings are provided at 
the top to receive the cradle trunnions on which the cradle pivots. 
Longitudinal recesses are cut in the inner surface of the lower portion 
of the cradle for the reception of the guides on the jacket of the gun. 

A seat is provided on the left side of the trail for the gunner who 
sets the sights and fires the gun, and one on the right for a cannoneer 
who sets the range and operates the breech. 



101 




102 

TJio ''Mi& ooTriar^ tojJ 1 fc,n*J' main shields and the apron are provided 
for the protection of the personnel against gun fire. 

The recoil cylinder is contained in the spring case in the upper por- 
tion of the cradle and is surrounded by two sets, inner and outer, of 
four sections each, of counterrecoil (running-out) springs, these 
being held under initial compression between an external flange on 
the front end of the recoil cylinder and an internal flange at the rear 
end of the outer spring case. The cylinder is attached and secured to 
the rear end of the gun by two nuts, while the piston rod with piston, 
which fits inside of the cylinder, is secured to the forward "end of the 
spring case. The piston rod is bored out for the reception of the 
counter recoil buffer which is secured in the rear end of the cylinder. 

Upon being fired the gun recoils, carrying with it the recoil cylin- 
der. The oil is forced to pass from in front of the stationary piston 
to the rear through grooves of graduated depth which set up an 
hydraulic resistance, thus checking the energy and bringing the gun 
to rest. In recoiling, the gun further compresses the two sets of 
springs which, after the gun has reached its maximum recoil, cause 
it to return to battery. The counter recoil buffer displaces the liquid 
in the rear end of the piston rod, the liquid being forced to escape 
over the tapered flats, thus resulting in the gun returning to battery 
without shock. 

A gravity tank is bolted to the front end of the recoil mechanism, 
which insures the cylinder being constantly filled, and is protected 
from gun fire by a shield. 

The angle of sight level is carried on a bracket riveted to the under- 
side of the rocking bar at the rear end and is adjusted by a leveling 
screw to which is attached a micrometer disc for setting off the 
angle of sight. 

The range indicator is fitted to the right side close to the handwheel 
and consists of a meter scale ring graduated on its face in hundreds 
of meters, the periphery of the ring being graduated in mils. The 
mechanism allows an elevation of 16 and depression of 5. 

The elevating gear is divided into two portions, upper and lower, 
and so arranged that the gun may be elevated or depressed without 
altering the line of sight. 

The traversing gear is pivoted to a bracket fastened to the trail at 
the rear end of the top carriage, and is operated by a handwheel 
extending out to the left side by means of which the gun may be 
traversed 72 mils right or left from center. A scale strip and pointer 
indicate the angle of traverse. 

Wooden wheels, 56 inches in diameter, are used, having steel tires 
3 inches in width. Drag washers free to rotate about the hubs are 
secured by the dust cars. 



103 




104 




105 

The tire brake is for use in traveling, and is always used when firing. 
Brake arms are pivoted at one end to a bracket on the trail and have 
at their other end a cast-iron brake shoe which acts upon the tire of 
the wheel. The braking action is adjustable and brakes are operated 
by a lever having an eccentric link at its end. 

The sights used are the rocking-bar sight and panoramic sight, 
model of 1917, which are located on the left side of the carriage. 

Fixed ammunition is used in this 75-millimeter field gun and is 
made up of either common shrapnel or common steel shell. Shrap- 
nel rounds are issued with the projectiles filled and fuzed; the shells 
rounds are issued filled but not fuzed, and contain an adapter with 
booster charge. 

The projectiles average in weight; shrapnel, 16 pounds fuzed; 
shell 12.3 pounds fuzed. The components of one round are the 
cartridge case with primer, powder charge, projectile, and fuze in 
shrapnel, and adapter and booster in shell. 

75-MILLIMETER GUN MATERIEL, MODEL OF 1917 (BRITISH). 

A battery of British 75-millimeter gun carriages is accompanied 
by the following vehicles: 

75-millimeter gun carnage limber, model of 1917, (British). 1 

75-millimeter gun carriage limber, model of 1918. 1 

75-millimeter gun caisson, model of 1918. 

75-millimeter gun caisson limber, model of 1918. 

Forge limber, model of 1902 ML 

Store limber, model of 1902 MI. 

Battery and store wagon, model of 1917. 

Battery reel, model of 1917. 

This gun was formerly 3.3 inches in caliber but was modified to 
75 millimeter giving interchangeability with French ammunition. 
All of this materiel used by the American Army was manufactured 
in the United States. The gun carriage limber, model of 1917, is of 
British design. 

1 Either one of the above limbers may be issued. 



75-MILLIMETER GUN CARRIAGE LIMBER, MODEL OF 

1917 (BRITISH). 



The standard British limber carries cartridges horizontally, but 
is not arranged with compartments or diaphragms. The American 
product of the British limber is superior to the standard British 
vehicle in that diaphragms are included in the ammunition chests. 
The limbers are, however, fitted with wooden poles, which are more 
liable to breakage than steel poles; they have single draft hooks, 
instead of double trees for equalizing the pull on the braces; the pintle 
latch is not so effective as the American, nor the ammunition chest 
doors so well suited to their purpose; and they are not adapted to 
the American harness, as the distance from the neck yoke to the 
draft hook is 6-inches shorter than in the American design and our 
harness can not be so readilv connected to the neck voke. 




FRONT VIEW OF LIMBER. 

Weights, dimensions, etc. 

Weight, complete, empty pounds. . 1, 016 

Weight of tools and equipment carried do 114 

Weight of ammunition carried do .... 516 

Weight, completely equipped and loaded do . . . . 1, 646 

Weight of gun, carriage and limber, completely equipped with 21 rounds of 

ammunition pounds. . 4. 591 

Diameter of wheels inches . . 56 

Width of track do. ... 60 

Turning angle with carriage degrees . . 70 

The British design of gun carriage limber is constructed of a frame 
consisting of two middle and two outer rails connected at the front 
and center by a bar and braces and surmounted by an ammunition 

chest of steel. 

(106) 



107 



K 



I 



s 

VJ 



I 




108 




fc 



109 

The chest opens at the rear and is fitted with perforated diaphragms 
for carrying 24 rounds of fixed ammunition and a compartment in 
the center holding two wooden trays for small stores. 

The pole is of wood, protected at the front end by steel wrapping 
plates and fitted with a neck yoke for use with breast collar harness. 




REAR VIEW OF LIMBER. 

The axle is a seamless steel tube fixed to the rails by flanges, and 
the wheels are the same as those used on the gun carriage. 

This limber is used only in connection with the 75-millimeter gun 
carriage, model of 1917 (British). 

The 75-millimeter gun carriage limber, model of 1918 (American) 
a description of which may be found on page 110, can be used as an 
alternate for this vehicle. 



75-MILLIMETER GUN CARRIAGE LIMBER, MODEL 

CF 1918. 



The limber is of American design, and is of metal throughout, 
excepting the spokes and felloes of the wheels. The frame consists 
of a middle rail and two side rails. The middle rail is in the form of 
a split cylinder, one-half passing below and the other half above 
the axle, uniting in front to form a seat for the pole and in the rear to 
form a seat for the pintle-bearing guide. An automatic pole support, 
described on page 160, is provided. 

The ammunition chest is a rectangular steel box, having a door at 
the rear hinged at the bottom, and swinging downward to an approx- 
imately horizontal position. Three perforated diaphragms within the 
chest support 18 rounds of fixed ammunition and 3 tubular oil cans. 

The axle is of forged steel, made in one piece. The standard 56-inch 
wheels are used. See page 158. 

This limber is used in connection with American, British, and 
French 75-millimeter materiel. 

Weights, dimensions, etc. 

Weight complete, empty pounds.. 963 

Weight of tools and equipment carried, oil cans filled do 134 

Weight of ammunition carried (shrapnel) do 365 

Weight of fuze boxes, loaded do 62 

Weight, completely equipped and loaded do 1,524 

Rounds of ammunition carried in limber chest . 18 

Diameter of wheels inches. . 56 

Width of track do 60 

Free height under limber do 24 

Turning angle with carriage degrees. . 78 

(110) 



1 1 1 




REAR ViEVV OF LIMBER. 




18322820 8 



FRONT VIEW OF LIMBER. 



112 




75-MILLIMETER GUN CAISSON, MODEL OF 1918. 



The caisson consists of a steel chest carried on wheels and axle by 
means of a spring support. This support consists of helical springs 
held by suitable axle and chest brackets at each end of the chest. 
The Belleville springs absorb the shock of rebound. 




FRONT VIEW OF CAISSON. 

The chest carries 70 rounds of ammunition arranged in 5 horizontal 
rows of 14 each. Protection from small-arms fire is provided by the 
front door, rear plate, and apron, which are made of armor plate. 
The chest provides seats for three cannoneers, and is equipped with 
fastenings for carrying a full complement of tools. A rack is provided 
at the back of the chest for carrying fuze boxes. On the front left 
side of the chest is fastened the fuze setter. 

The caisson is equipped with a short pole and lunette combined 
with a pole prop. On the rear the standard pintle is provided. 

(113) 



114 





gfe g^ia 




i I 



115 



Standard 56-inch wheels are used and band brakes are provided. 
See page 158. 




GUN CAISSON AND GUN CAISSON LIMBER, LIMBERED. 

Weights, dimensions, etc. 

Weight complete, empty . pounds. . 1, 425 

Weight of tools and equipment carried do 62 

Weight of ammunition carried (shrapnel) do 1, 421 

Weight of fuze boxes, loaded .do 124 

Weight completely equipped and loaded do 3, 032 

Weight with limber completely equipped and with 106 rounds of ammuni- 
tion pounds.. 4,961 

Rounds of ammunition carried 70 

Diameter of wheels inches. . 56 

Width of track do 60 

Free height under caisson do 21 

Turning angle with limber degrees. . 81 



75-MILLIMETER GUN CAISSON LIMBER, MODEL OF 

1918. 



The gun caisson limber is practically the same as the gun carriage 
limber, model of 1918, except that the chest is larger and carries 
more ammunition. Each diaphragm is perforated with 39 flanged 
holes, which accommodate 36 rounds of ammunition, and three 
tubular oil cans. 

This limber is used in connection with the American, British, and 
French 75-millimeter materiel. 




FRONT VIEW OF CAISSON LIMBER. 

Weights, dimensions, etc. 

Weight, complete, empty pounds. . 1, 003 

Weight of tools and equipment carried (oil cans filled) do 134 

Weight of ammunition carried (shrapnel) do 730 

Weight of fuze boxes, loaded do 62 

Weight, completely equipped and loaded do 1, 929 

Rounds of ammunition carried in limber chest 36 

Diameter of wheels inches . . 56 

Width of track do 60 

Free height under limber .' do 24 

Turning angle with caisson degrees. . 81 

(116) 



117 




m 

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2 



3-INCH GUN MATERIEL, MODEL OF 1902. 



When the United States entered the World War there were on 
hand approximately 544 3-inch field guns, model 1902, and the 
necessary equipment therefor. The 3-inch, model 1902, materiel 
includes gun, carriage, limber, caissons, caisson limbers, battery 
wagons, forge limbers, store wagons, store limbers, combination 
battery, store wagons and limbers, battery reel, also reel and carts, 
as issued to the 75-millimeter materiel. 

The needs of the fighting army received first attention, but a large 
number of troops in the training areas and camps required materiel 
for use in their preliminary instructions; thus 154 batteries of 3 -inch 
model 1902, materiel were distributed for training purposes in the 
United States which were considered substitutes for the 75-millimeter 
materiel. 

The 3-inch field gun, American model 1902-1904-1905, is equipped 
with a breechblock of the interrupted-screw type. The breech 
mechanism consists of a handle pivoted vertically to provide hori- 
zontal movement of the handle to the right to open the breechblock. 
In opening, the mechanism performs two functions: Revolves the 
breechblock, releasing it from the threads, and then swings the block 
open. At the same time the cartridge case is ejected from the gun. 
In closing, the threaded movement firmly seats the cartridge in the 
powder chamber, and the threads withstand the backward thrust 
of the powder gases. 

The recoil mechanism is of the hydro-spring type, with the housing 
attached to the carriage, and located underneath the cannon. The 
firing mechanism, in the latest design, is operated either by a lanyard 
attached to the trigger, or by means of a firing handle on the cradle, 
and is of the continuous-pull type. \Yhen the breechblock is 
unlocked the gun can not be fired. 

Weights, dimensions, and ballistics. 
Weight of gun: 

Models of 1902 and 1904 pounds. . 835 

Model of 1905 do .... 788 

Caliber - inches . . 3 

Length of gun do 87. 8 

Length of bore do 84 

Length of rifled portion of bore do 72. 72 

(118) 



11!) 




ViEvV Ur CARRIAGE. 




REAR VIEW OF CARRIAGE. 



120 

Rifling: 

Number of grooves 24 

Width of grooves inch . . 0. 2927 

Depth of grooves do 0. 03 

Width of lands do 0. 01 

Twist, right-hand: 

Models of 1902 and 1904; 1 turn in 50 calibers at origin to 1 turn in 25 cali- 
bers at 12.52 inches from muzzle, thence uniform. 

Model of 1902: turn at origin to 1 turn in 25 calibers at 9.72 inches from 
muzzle, thence uniform. 

Weight of projectile (filled and fuzed) pounds. . 15 

Weight of cartridge case do 2. 25 

Weight of fixed ammunition (1 round) do .... 18. 75 

Capacity of cartridge case cubic inches. . 66. 5 

Muzzle velocity feet per sec . . 1, 700 

Maximum pressure per square inch , pounds . . 33, 000 

Range at 15 elevation yards . . 6, 000 

Maximum range (approximately) do 8, 500 

Weight of carriage with 4 rounds of ammunition, weighing 75 pounds. pounds. . 1, 685 

Weight of gun and carriage , fully equipped do 2, 520 

Weight at end of trail, carriage limbered do 115 

Diameter of wheels inches . . 56 

Width of track do 60 

Length of recoil of gun on carriage do 45 

Height of axis of gun do 40. 875 

Height of line of peep sight do 44. 9 

Length of peep-sight radius do 36. 75 

Maximum angle of elevation degrees . . 15 

Maximum angle of depression do 5 

Amount of traverse of gun and carriage mils . . 140 

Rounds of ammunition carried on carriage 4 

3-INCH GUNS, MODELS OF 1902, 1904, AND 1905, AND CARRIAGE MODEL 

OF 1902. 

The guns are of three models, 1902, 1904, and 1905, and are prac- 
tically the same except that the latter two models differ from the 
1902 model in breech mechanism and the 1905 model is 50 pounds 
lighter in weight. 

The gun is built up of nickel steel and consists of a tube, the rear 
portion of which is enveloped by a jacket which also projects beyond 
the rear end forming a recess for the breech block. A locking hoop 
is shrunk on the tube and the forward end of the jacket to secure 
the latter to the tube. The front clip is a short hoop shrunk on the 
tube near the forward end which guides the gun in recoil. 

The breechblock on all three models is of the interrupted-screw 
type, and rotates in the block carrier which is hinged to the rear 
end of -the tube on the right, side. The block of the 1902 model has 
two threaded and two slotted sectors and the block of the 1904 and 
1905 models which have identical breech mechanisms, has four 
threaded and four slotted sectors. The breechblock is operated 






c 

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I 





(122) 



. ill ! ! 



" 1 




124 

by a lever pivoted to a lug on the block carrier which has at its outer 
end a handle and at its pivot end, a segment of a bevel gear, meshing 
with a corresponding segment on the rear face of the block. On 
pulling the handle to the right, the first 117 rotates the block until 
the threaded sectors are disengaged. A further movement of 90 
swings the block and carrier on its hinge until free of the bore. 

The firing pin is eccentrically "located in a recess in the block, 
when the breech is open. As the breech is closed the pin is automat- 
ically moved to one side until it is in alignment with the axis of the 
bore and primer of the cartridge case. This is a safety feature 
which prevents the accidental discharge of a round before the breech 
has been fully closed. 

The carriage is known as model of 1902. A tapering box-shaped 
trail is secured to brackets around the axle and has at its rear end a 
spade and float. Two compartments are provided in the trail, one 
for tools and one for the rear sight. A seat is riveted to each side 
of the trail, one on the left for the gunner, and one on the right for 
a cannoneer. In front of the compartments are two cross transoms 
which form a support for the elevating mechanism. The cradle has 
riveted to its underside a pintle which seats in a pintle socket se- 
cured to the axle, by means of which the cradle and gun is rotated. 

The top and main shield and an apron are provided for the pro- 
tection of the personnel from gun fire. 

The recoil mechanism is of the hydro-spring type. The recoil 
cylinder is fastened to the gun lug and therefore recoils with the gun. 
The piston rod, "being secured to the cradle head, remains stationary 
during recoil. Throttling during recoil is obtained by the use of 
three throttling bars, on the interior of the recoil cylinder, the piston 
having three slots cut in it to correspond to the throttling bars. 
During recoil the piston is stationary and the hydroline oil in the 
cylinder is forced past the piston through the slots. As the throttling 
bars, due to their increasing size, gradually close the slots in the 
piston, the gun is gradually brought to a stop. 

The counterrecoil mechanism consists of three nests of inner and 
outer springs which function to return the gun to battery and serve 
to partially check the recoil. The counterrecoil buffer consists of a 
tapered rod secured in the end of the cylinder which enters the hollow 
end of the piston rod, displacing the oil therein and preventing shock 
when the gun returns to battery. 

The elevating mechanism is of the double-screw type, consisting of 
a screw pivoted to the rear end of the rocker, which is moved up or 
down by the rotation of a bevel gear threaded on its interior surface. 
This bevel gear is rotated by a bevel pinion operated by a crank 
handle on either side of the trail 



125 




12G 

Traversing is accomplished by means of a traversing shaft operated 
by a handwheel on the left side of the carriage. This shaft is 
threaded and passes through a nut which is pivoted to the cradle. 
The nut being secured to prevent its turning, swings the cradle in 
traverse, when the traversing mechanism is operated. 

A lock is provided for locking the cradle to the trail in order to 
relieve the elevating and traversing mechanisms of any unnecessary 
strains during traveling. 




CARRIAGE AND LIMBER HAULED BY TRACTOR. 

Seats are supported on the axle on each side of carriage in front of 
the shield for the cannoneers, when traveling. Foot rests are pro- 
vided which also support the brake levers and ammunition carriers, 
there being four of the latter which make it possible to open fire 
quickly if necessarv . 




CARRIAGE AND LIMBER IN TRAVELING POSITION. 

The brakes are of the shoe type and may be operated from either 
in front or rear of the shield, in the former case when traveling, and 
in the latter case when in firing position. 

Standard 56-inch wheels are used. See page 158. 

The instruments provided for sighting and laying the piece include 
line sights, a rear sight, a front sight, a panoramic site, and a range 
quadran t. 

Three kinds of fixed ammunition are used in the 3-inch gun, 
models of 1902, 1904, and 1905, namely, common steel shell, common 
shrapnel, and high explosive shrapnel. Each round is issued with 



127 




1832282 



128 




129 

projectiJes filled and fuzed. The weight of the projectile is 15 pounds 
and the total weight of one round is 18.75 pounds. 

3-INCH GUN MATERIEL, MODEL OF 1902. 

This materiel includes the following: 

3-inch field gun, model of 1902, 1902 or 1905 mounted on 
carriage, model of 1902. 

3-inch gun limber, model of 1902 and 1916. 

3-inch gun caisson, model of 1902 and 1916. 

Forge limber, model of 1902 and 1902 Ml. 

Battery wagon, model of 1902, 1902 Ml and 1917. 

Store limber, model of 1902 and 1902 Ml 

Store wagon, model of 1902, 1902 Ml and 1917. 

Battery reel, model of 1917. 
The above materiel is entirely of American design and manufacture. 



3-INCH GUN LIMBER, MODEL OF 1902. 



The limber, excepting the spokes and felloes of the wheels, is of 
metal throughout. The principal parts are the wheels, axle, frame, 
ammunition chest, pole, doubletree, singletrees, and neck yoke. 

The wheels and wheel fastenings are the same as, and interchange- 
able with, those used on the carriage. The axle is hollow, of a single 
piece of forged steel, the axle body being provided with lugs, to which 
the middle and side rails of the frame are riveted. 

The side rails are of channel shape, divided at the front, one branch 
being led forward and secured to the middle rail near the pole seat, 




REAR VIEW OF LIMBER. 

while the other branch is utilized as a foot-rest support. The foot 
rest is a perforated steel plate formed to shape and riveted to the 
middle and side rails in front of the ammunition chest. The rear 
ends of the side rails project slightly beyond the chest to form steps 
for the use of the cannoneers in mounting. 

The frame consists of a middle and two side rails riveted to the 
axle lugs. The middle rail is in the form of a split cylinder, one-half 
passing below and the other half above the axle, which are joined in 
front to form a seat for the pole and in rear to form a seat for the 
pintle bearing. The pintle bearing is of bronze, made in halves and 
bored out to take the pintle shank. The pintle has a swiveling motion 
of 360 upon its shank, but is kept in its normal position by the spring 
in the bearing. 

The doubletree and singletrees are formed of flange steel. Two 
doubletree rods each from the ends of the doubletree to the tie-rod 

(130) 



131 

clamps on the axle to which they are pinned. A pole prop is hinged 
to the rear end of the pole and when not in use it is secured by fasten- 
ings under the limber frame and the prop-chain button on the foot rest. 

The ammunition chest is a rectangular steel box built up of sheet 
steel and riveted together. The chest door is hinged at the bottom 
and swings downward and to the rear to an approximately horizontal 
position, where it is held by two door chains, and is held in its closed 
position by a shot bolt at each of the upper corners and by a lock in 
the middle. 

Inside of the chest the cartridges are supported by three vertical 
diaphragms, flanged all around and riveted to the body of the chest. 
Each of the diaphragms is perforated with 39 flanged holes. Corre- 
sponding holes in the middle and rear diaphragms are connected by 
conical brass tubes, which are cut away on top to reduce weight. 
These connecting pieces support the front end of the cartridge case 
and enable empty cases to be carried. The rear end of the connecting 
piece is turned over the rear face of the flange of the perforation in 
the rear diaphragm, and forms a stop for the rim of the cartridge 
case. The chest door closes against the head of the case so that the 
cartridge is firmly held in position. Suitable finger clearances are 
cut in the flange of each cartridge hole in the rear diaphragm to 
enable the fingers to get a good hold on the rim of the case in with- 
drawing it from the chest. 

Seats for three cannoneers are provided and the paulin issued with 
each limber serves as a seat cushion. Watering buckets are carried 
in suitable compartments provided for them between the seat and the 
chest. At each end of the seat is a handrail which projects above 
the top of the chest. At the front a lantern and two picket 
ropes are carried. Brackets for carrying an ax, a shovel, and pole 
prop are provided under the limber. All of the implements are 
secured in their brackets by leather straps, and held by strap fasteners 
provided for that purpose. With each limber are issued three oil 
cans, each of the general form of a cartridge and of a capacity of 
approximately two-thirds of a gallon. They are intended for hydro- 
line, lubricating, and coal oil, and are to be carried inside the chest 
in the central vertical row of cartridge holes. 

Weights, dimensions, etc. 

Weight, complete, empty pounds. . 964 

Weight of tools and equipment carried do .... 101 

Weight of ammunition carried do .... 675 

Weight, completely equipped and loaded do 1, 740 

"Rounds of ammunition carried in limber chest 36 

Diameter of wheels inches . . 56 

Width of track. do 60 

Free height under limber do 22 

Turning angle with carriage .degrees. . 80 

Turning angle with caisson do 75 



3-INCH GUN CAISSON, MODEL OF 1902. 



This caisson, with the exception of the spokes and felloes of the 
wheels is of metal throughout. 

The frame is diamond-shaped and composed of two channel section 
side rails riveted to lugs on the axle and meeting in front and rear 
at the lunette and pintle, respectively. 




FRONT VIEW OF CAISSON. 

The ammunition chest is a rectangular steel box of flange steel 
containing three vertical diaphragms which support 70 rounds of 
ammunition. Caissons having serial numbers 1141 to 1284, inclusive, 
have provisions for but 56 rounds. 

The door of the chest is in the rear and hinged at the top, the door 
opening upward and held at each end by a prop. 

An apron of armor plate is hinged under the axle and may be 
secured in a horizontal position for traveling. 

A fuze-setter bracket is pivoted to the apron hinges on the right 
side of the carriage at the rear. t is raised and secured for traveling. 

The road brake is designed similar to that of the gun carriage, with 
all parts as far as possible being interchangeable. The standard 
56-inch wheels are used. 

(132) 



133 

Weight, dimensions, etc. 

Weight, empty pounds. . 1, 424 

Weight of tools and equipment carried do .... 84 

Weight of ammunition carried do . ... 1, 312. 5 

Weight, completely loaded and equipped do .... 2, 820 

Rounds of ammunition carried 70 

Diameter of wheels inches. . 56 

Width of track do 60 

Free height under caisson do. .-. . 22. 5 

Turning angle degrees. . 75 



3-INCH GUN CAISSON, MODEL OF 1916. 



The frame consists of two side rails and a middle rail braced by 
tie rods, and by the ammunition chest to which they are riveted. 

The chest is a rectangular flange steel box containing three ver- 
tical diaphragms supporting 70 rounds of ammunition. 

The door is hinged to the front of the chest, swings upward on 
its hinges and is held by a door prop on the left side. 

An apron of armor plate is hinged below the chest for the protec- 
tion of the personnel. 




FRONT VIEW, SHOWING DOOR SWUNG UPWARD EXPOSING AMMUNITION. 

Band brakes are used similar to those on the 75-mm. gun car- 
riage, model of 1916, several parts of which are interchangeable. 
Brakes are applied by a hand lever on the right side, operated by 
one of the cannoneers seated on the chest. 

Weights, dimensions, etc. 

Overall length (traction pole removed) inches. . *64 

Overall width do *74 

Overall height do *57 

Weight, empty pounds. . 1, 384 

Weight of tools and* equipment carried do .... 53. 5 

W T eight of ammunition carried do . ... 1, 312. 5 

Weight, completely equipped and loaded , do .... 2, 750 

Rounds of ammunition carried do .... 70 

Diameter of wheels inches. . 56 

Width of track do 60 

Free height under caisson do 21 

Turning angle .degrees. . 81 

*Approximately. 
(134) 



135 



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2? 

b 




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61 



ro 



137 

3-INCH GUN LIMBER, MODEL OF 1916. 

With the exception of the chest, the limber is the same as the 
75-millimeter gun caisson limber, model of 1918. The main differ- 
ence in the chest is in the size of the holes in the diaphragms, they 
being larger to accommodate 3-inch ammunition. 

Weights, dimensions, etc. 

Overall length inches . . * 120 

Overall width do. ... * 74 

Overall height do ... * 63 

Weight, complete, empty pounds. . 987 

Weight of tools and equipment carried (oil cans filled) do 113 

Weight of ammunition carried '. .do 675 

Weight, completely equipped and loaded do J, 775 

Rounds of ammunition carried in limber chest do 36 

Diameter of wheels inches . . 56 

Width of track I do. ... 60 

Free height under limb'er . do 24 

Turning angles with carriage degrees. . 80 

Turning angle with caisson do 81 

* Approximately. 



BATTERY WAGON, MODEL OF 1902. 



The frame consists of two side rails joined at the front to form a 
seat for the lunette bracket and projecting directly to the rear beyond 
the axle. A forge vise is securely fastened to the left side of the frame 
in place of the handle. 




RE\R VIEW OF BATTERY WAGON. 

The chest is of wood and is bolted to the side rails. The interior 
is divided into four compartments; the largest being accessible 
through a hinged lid at either end of the top. The other three com- 
partments are in the lower rear portion of the chest, and are entered 
by a door at the rear end which opens downward. Of the three 
compartments, the right one is for the saddler's chest ; the left one 
for the carpenter's chest, and the middle one for the cleaning mate- 
rials and small stores chest. In the larger compartment is carried 
the grindstone and frame; the jackscrew; and the packing chest 
containing spare breech mechanism. A chest for spare sights is 
furnished, which may be carried either in the battery or store wagon. 

(138) 



139 

In rear of the axle and under the chest are carried three oil cans 
of 5 gallons capacity each. 

Fastenings are provided on either side of the chest for carrying 
the two spare wheels. 

The wheels used and carried are standard 56-inch. See page 158. 

This battery wagon is used only in connection with the 3-inch gun 
materiel, model of 1902. 

Weights, dimensions, etc. 

Weight of battery wagon, empty . pounds. . 1. 244 

Weight of battery wagon, completely equipped and loaded do. ... 2, 747 

Diameter of wheels inches... 56 

Width of track do. ... 60 

Free height under wagon ^ ... do 26 

Turning angle degrees. . 75 

BATTERY WAGON, MODEL OF 1902 MI. 

The battery wagon, model of 1902 MI, differs from the model of 
1902 in the following respects: 

The chest with attachments is stronger, better braced, and at- 
tached in a better manner to the frame. 

The weight of the spare wheels is carried directly by the axle 
instead of at the top of the chest. 

The parts of the chest are bolted and screwed together so that 
they may be readily disassembled if necessary. The corners are not 
dovetailed but reinforced with corner irons inside and out. 

This battery wagon is used only in connection with the 3-inch gun 
materiel, model of 1902. 

Weights, dimensions, etc. 

Weight of battery wagon, empty : pounds . . 1. 444 

Weight of battery wagon, completely equipped and loaded do 2, 947 

Diameter of wheels inches. . 56 

Width of track do 60 

Free height under wagon do 24. 5 

Turning angle with limber degrees. . 75 

Weight (approximate) at lunette, loaded pounds. . 112 



STORE WAGON, MODEL OF 1902. 



The store wagon is the same as the battery wagon, model of 1902, 
with the exception that the vise is omitted and a frame handle at- 
tached in its place, and the body has but a single compartment, with 
two doors on top. As on the battery wagon, the store wagon carries 
two spare wheels and three oilcans. 




SIDE VIEW OF STORE WAGON. 

The store wagon is intended primarily for carrying silch stores, 
spare parts, and materials as can be carried in the battery wagon and, 
in addition, such stores as may be designated by proper authority. 

Tire brakes are used operated by a hand lever on the right side 
of the body. 

The wheels used and carried are the standard 56-inch. See 
page 158. 

For detailed description and table of weights, dimensions, etc., 
see page 139. 

(140) 



141 

STORE WAGON, MODEL OF 1902 MI. 

The store wagon, model of 1902 MI, is the same as the battery 
wagon, model of 1902 MI, with the exception of the differences as 
noted in the description of the battery store wagon, model of 1902. 

For detailed description and table of weights, dimensions, etc., 
see page 139. 



142 




FORGE LIMBER MODEL OF 1902. 



The frame of the forge limber is identical in all its parts with that 
of the 3-inch gun limber, model of 1902. It consists of a middle and 
two side rails, the middle rail being in the form of a split cylinder, 
one half passing below and the other half above the axle, uniting in 
front to form a seat for the pole and in the rear to form a seat for 
the pintle bearing guide. 

The chest is a rectangular flange-steel box having a lid hinged 
along the front edge of the chest body. The lid is flanged all around, 




1 



TOP VIEW SHOWING INTERIOR OF FORGE LIMBER. 



Shot 



fitting over the body of the chest to make it water-tight, 
bolts on the rear face of the chest secure the lid when closed. 

The interior of the chest is divided into five compartments by 
four vertical steel partitions. The middle compartment, which is 
the largest, is fitted to take the field forge, the anvil, and several 
small tools, the next compartment on either side carries horseshoes 
and horseshoe nails, and the end compartments are fitted with 
fastenings -for carrying smiths' and machinists' tools. A tubular oil 
18322820 10 (143) 



144 




145 

can is carried under each end of the chest, and various implements 
are secured to the chest by straps provided for that purpose. 

Weights, dimensions, etc. 

Weight of forge limber, empty, without equipment pounds . . 958 

Weight of forge limber, complete, equipped and loaded do. ... 1, 577 

Weight of store limber, empty, without equipment do 955 

Weight of store limber, complete, equipped and loaded do ], 106 

Diameter of wheels inches. . 56 

Width of track do 60 

Free height under limber do 26. 5 

Turning angle with battery wagon degrees. . 75 



FORGE LIMBER, MODEL OF 1902 MI. 

The forge limber, model of 1902 MI, is identical with .the 1902 
model, with the exception that the 1902 MI model has an automatic 
pole support, which is described on page 160. 

The forge limber is used in connection with the American, British, 
and French 75-millimeter materiel, and the 3-inch gun materiel, 
model of 1902. 

A detailed description and table of weights and dimensions is given 
in a preceding article on forge limber, model of 1902, page 143. 



STORE LIMBER, MODEL OF 1902. 



The store limber is practically the same as the forge limber, model 
of 1902, except that the chest is fitted with compartments for carry- 
ing fire-control equipment, some of the compartments being padded 
to protect the contents from injury. 

For description and table of weights and dimensions, see preceding 
article on forge limber, model of 1902. 




TOP VIEW SHOWING INTERIOR OF STORE LIMBER. 

STORE LIMBER, MODEL OF 1902 Ml. 

The store limber, model of 1902 Ml, is identically the same as the 
store limber, model of 1902, with the exception that it is fitted with 
an automatic pole support, description of which will be found on 
page 160. 

For description and table of weights and dimensions, see preceding 
article on forge limber, model of 1902. 

STORE LIMBER, MODEL OF 1902 Ml. 

The limber is used in connection with the American, British, and 
French 75-millimeter materiel, and the 3-inch gun materiel, model 
of 1902. 

(146) 



BATTERY AND STORE WAGON, MODEL OF 1917. 



The battery and store wagon is made of metal throughout, with 
the exception of the spokes and felloes of the wheels. The frame is 
built up of two channel section side rails connected at the rear and 
intermediate points by similar channels. The side channels are bent 
inward near the front, meeting and forming a seat in which the 




REAR RIGHT SIDE VIEW OF BATTERY AND STORE WAGON. 

lunette bracket is riveted. At the rear of the frame is a compartment 
for carrying recuperator, lubricating, and coal oil cans. 

The chest is divided into compartments for carrying various articles 
of battery equipment. The top compartments have horizontally 
hinged lids and the lower compartments in front and rear have 
vertical swing doors. Fastenings are provided on each side of the 
chest for carrying spare wheels, and provision is made for carrying a 

spare limber pole. 

(147) 



148 



. 

ill! 




149 

The battery and store wagons are identical, except that the battery 
wagon carries a vise on the front end of the frame and a crow r bar 
bracket below the frame on the right side, and the store wagon con- 
tains packing strips and accessories for carrying a grindstone in the 
upper rear compartment. 

Standard 56-inch wheels are used. See page 158. The battery 
and store wagon is used in connection with the American, British, 
and French 75-millimeter materiel, and with the 3-inch gun materiel, 

model of 1902. 

Weights, dimensions, etc. 

Weight of battery wagon, empty pounds. . 1, 705 

Weight of battery wagon, completely equipped and loaded do 3, 325 

Weight of store wagon, empty do 1, 705 

Weight of store wagon, completely equipped and loaded do 3, 590 

Diameter of wheels inches. . 56 

Width of track do 60 

Free height under wagons do 24. 5 

Turning angle with limbers , degrees . . 75 

Weight (approximate) at lunette of both wagons, loaded pounds. . 112 

Overall length ". inches. . * 132 

Overall width do * 74 

Overall height do. ... * 88 

* Approximately. 



BATTERY REEL, MODEL OF 1917. 



The battery reel, model of 1917, is a single two-wheeled vehicle 
which is drawn by 4 horses. It is designed to carry, lay, and 
recover 4 miles of insulated cable, and in addition carries 2 steel 
chests containing fire-control instruments. 

The frame is composed of two side rails connected by cross members 
and diagonal braces. Near the front, the side rails converge and are 
riveted to the pole socket. Axle brackets are riveted to the side rails, 




LEFT SIDE VIEW OF BATTERY REEL. 

in which are mounted the axle arms for the wheels and the drum 
shaft on which the cable drum rotates. 

On -each side of the drum are supports which are joined across the 
top by a seat for two men. Across the frame in front of the drum is 
secured an instrument chest divided into two compartments with 
separate hinged lids, the lids forming foot rests for the personnel on 
the seat. Across the frame in rear of the drum a large steel chest is 
supported on springs. It has a lid hinged at the front and provided 
with guide rollers for the cable at its rear. The larger fire-control 
instruments are carried in this chest in specially designed com- 
partments. 

On the right side of the drum is secured a steel case in which a 

plotting board is carried. 

(150) 



151 

At either end of the drum is a sliding leather-faced cone which is 
controlled by a hand lever at the left end of the operator's seat. 
When either cone is engaged, the other is disengaged. The cone on 
the left is connected directly to a gear train driven by a gear attached 
to the wheel hub, and when er gaged causes the drum to revolve. 
As the brake cone on the right is engaged the clutch cone is thrown 
out of engagement. The wire, when being laid out, leaves from the 
top of the drum, passing between the guide rollers attached to the 
rear chest. 

The cart, model of 1918, together with the reel, model of 1909MI, 
is issued in lieu of the battery reel, model of 1917, for motorized 

batteries. 

Weights, dimensions, etc. 

Overall length (tractioa pole removed) inc hes. . 74 

Overall width do. ... 73. 75 

Overall height do. ... 65 

Weight of reel (without load) pounds. . 1, 385 

Weight of reel, completely equipped and loaded do. ... 2, 005 

Diameter of wheels , inches. . 56 

Width of track do 60 

Free height under reel do 19 

Length of wire carried (approximately) miles. . 5 



REEL, MODEL OF 1909 Ml. 



The reel, model of 1909 Ml, is a two-wheeled vehicle designed to 
cany, lay, and recover 8 miles of insulated cable. It has interchange- 
able pole connections which enable it to be adapted to either horse 
or motor traction. 

The frame is composed of special shaped pressed steel members 
connected by gusset plates and reinforce pieces, the pole socket at 
the front, automatic pole support, a pintle at the rear, and the assem- 
bled axle. 




REAR VIEW OF REEL. 

Two drums, which carry the cable are mounted end to end on an 
s axle which rests in the upper ends of the axle brackets. In order to 
lay the wire, the drums are disengaged from the clutch, permitting 
them to revolve free upon their axes, but controlled by the braking 
action of the drum latch and drum brake or the friction clutch when 
applied for that purpose. To' recover the cable or wind it on the 
drums, the clutch in the right drum is applied, and the drum made to 
revolve, by means of the chain driving gear attached to the right 
wheel. The left drum is driven by the right drum through a pin 
clutch which is operated by a handle in the left outer end of the left 

drum. 

(152) 



153 




154 

An operator's seat is secured to the right rear corner of the frame, 
and the controls placed within easy reach. The clutch connecting 
the drum driving gear and the right drum is located in a recess in the 
right drum head and operated by a handwheel at the upper end of a 
shaft mounted on the right axle bracket. 

A lever on 'the right side near the seat operates the drum latch for 
locking the right drum, and through the pin clutch, the left drum 
when they are at rest. A leather faced brake shoe attached to the 
drum latch lever may be brought against the flanged rim of the right 
drum end plate to act as a brake. 

A brake shoe controlled by a foot lever near the operator's seat may 
be brought to bear against the flanged rim of the left drum end 
plate. 




FRONT VIEW OF REEL. 

Wooden rollers are placed under the frame so that the wire will 
be laid out or recovered without injury to it. 

A tool box with lid opening on top is secured to the right of the 
pole bracket in the space between the side rail and front cross rail. 

The reel, model of 1909 Ml, together with the cart, model of 1918, 
is issued in lieu of the battery reel, model of 1917, for motorized 

batteries. 

Weights, dimensions, etc. 

Weight of reel (without load) : pounds. . 1, 459 

Weight of reel completely equipped and loaded do 2, 426 

Diameter of wheels inches. . 56 

Width of track do. ... 60 

Free height under reel do .... 19 

Turning angle with cart T degrees. . 75 

Length of wire carried yards. . 22, 880' 



CART, MODEL OF 1918. 



The cart is a two-wheeled vehicle made of metal throughout, with 
the exception of the spokes and felloes of the wheels and the packing 




% VIEW SHOWING REEL AND CART, LIMBERED. 

within the chest. It is designed to carry part of the fire-control 
equipment for the organization to which it is issued. 




REAR VIEW OF CART. 



The frame consists of a middle rail, two side rails, and two axle 
brackets, all of which support the chest. Tne forward end of the 

(155) 



156 




157 

middle rail is fitted with a lunette and the rear end with a pintle. 
Spiral springs are interposed between the side rails and axle brackets 
to absorb the shocks when traveling. In connection with the axle 
brackets, Belleville springs are used to take up rebound. 

The chest is made up of flange steel plates riveted together and 
fitted with doors, lock bars ; and packing devices, the interior being 
divided into 17 compartments of different sizes. The chest is also 
furnished with fixtures on the exterior for attaching an observation 
tower. 

The road brakes are of the contracting band type and are operated 
from the front of the cart or from the operator's seat on top of the 
chest by means of a brake lever on the right side. 

This cart, together with the reel, model of 1909M1, is issued in lieu 
of the battery reel, model of 1917, for motorized batteries. 

Weights, dimensions, etc. 

Overall length inches. . * 126 

Overall width do * 74 

Overall height. . . .- do * 62 

Weight, empty, without body equipment pounds. . 1, 676 

Weight, complete, fully equipped and loaded do 2, 004 

Diameter of wheels inches. . 56 

Width of track do 60 

Free height under cart (approximate) do 26 

Turning angle with reel (approximate) degrees. . 75 

Weight of instruments pounds. . 431 

* Approximately. 



THE 56-INCH WHEEL. 



All carriages and accompanying vehicles of the 3-inch and 75- 
millimeter materiel, of American design, are equipped with standard 
56-inch wheels, which are interchangeable for all vehicles of these 
materiels. 

The wheel is a modified form of the Archibald pattern, 56 inches 
in diameter, with 3-inch tires. The tires are of steel. An oil valve 
is provided so that the wheel can be oiled without removing it 




SIDE VIEW OF WHEEL. 

The wheel fastening consists of a bronze yoke fitting in the outer 
end of the axle arm and is accessible when the hub cap is removed. 

THE 57 BY 3.5 INCH WHEEL. 

In place of the above 56-inch wheel a 57 by 3.5 inch wheel may 
be used. 

It is similar in design to the 56-inch wheel, but is fitted with solid 
rubber tires. 

Like the 56-inch wheel it is interchangeable on all vehicles of the 
3-inch and 75-millimeter materiel. 

(158) 



REEL, MODEL OF 1917, FOR CAISSONS. 



One caisson in every battery is provided with a hand reel for tele- 
phone wire. It is riveted to the top of the caisson and contains 1 
mile of field wire so arranged that the current goes through all the 
wire. Terminals are provided for the connection of the instruments. 




REEL FOR CAISSON, MODEL OF 1917, MOUNTED ON A CAISSON. 

The reel for caisson, model of 1917, is a hand-operated reel for the 
transportation and handling of telephone wires. 

The frame is built up of two-flanged steel ends and two sides, 
riveted together with four angle-iron corner reinforces and riveted 
to the top of the chest. The reel is built up of two steel spool flanges 
mounted on a shaft, a spool riveted to the right flange and a basswood 
spool hub mounted between the spool flanges. 

The spool may be operated from either side. The crank on the right 
side is mounted on the shaft, and when not in use it can be removed 
and placed in its provided receptacle. The crank on the left side is 
connected with the spool through an 18 to 40 gear reduction. The 
crank shaft is fitted with a driving gear which meshes with a pinion 
18322820 11 (159) 



160 



on the shaft of the spool. Chains are provided on either end of the 
frame for locking the cranks when not in use. 

The reel is also fitted with a brake for controlling the speed of rota- 
tion when allowing wire to run out. The brake lever is pivoted on 
the brake-lever pin, and operated by a thong attached to the lower 





REEL FOR CAISSON, MODEL OF 1917. 

end of the lever. By pulling the thong the upper end of the lever is 
made to drag on the inside of the rim of the left spool flange. A 
brake-release spring, attached to the upper end of the lever, and a lug 
on the left shaft bearing, keeps the brake open when not in use. 

THE AUTOMATIC POLE SUPPORT. 

Late designs of limbers for 75-millimeter and 3-inch gun materiel 
are fitted with an automatic pole support. 

The pintle hook has a lug formed on its lower side, which projects 
backward and bears against the lower side of the lunette on the 
drawn vehicle, thus preventing the vertical rotation of the pintle. 



PIMTU BEMl.n* 6UIDC- 



'. , SICE* 

I ,FlNTlE KAHIN6 




SECTIONAL DIAGRAM OF POLE SUPPORT. 

The pintle bearing is pivoted by trunnion bolts permitting rota- 
tion in the vertical plane. A spring rod is pinned to a lug on the top 
of this bearing and carries the pole supporting spring. This spring 
is held between a collar on the rod and the pintle bearing guide so 
that when the weight of the pole on the coupled vehicle is put on the 
pintle it tends to compress the spring until the load is supported by it. 

On the pintle bearing bolt is another spring, which is compressed 
when the pintle is drawn back, thus relieving the shock of starting. 



4.7-INCH GUN MATERIEL, MODEL OF 1906. 



The 4. 7-inch, model of 1906, is a mobile field gun, designed to fire 
shrapnel or shell at greater ranges than the 75-millimeter guns. In 
order to increase the range, a 45-pound shell is provided to replace 
the old type 60-pound shell. The former projectile gives consider- 
ably higher muzzle velocity and longer range than the 60-pound pro- 
jectile. The life of the gun before relining is approximately 5,000 
rounds. 

Using the 60-pound shrapnel, a muzzle velocity of 1,700 foot- 
seconds is obtained, with a maximum range of 7,550 yards (6,903 
meters) at an elevation of -15. With the 45-pound shell, with a 
muzzle velocity of 2,050 foot-seconds, a maximum range of 8,700 
vards (7,900 meters) at an elevation of 15, under normal conditions. 




VIEW SHOWING CARRIAGE AND LIMBER IN TRAVELING POSITION. 

The 4.7 inch field gun is mounted on a carriage of the long-recoil 
type, in which the gun is permitted a sufficient length of recoil on the 
carriage to render the latter practically stationary under firing 
stresses. The gun, in recoil, is controlled by two spring cylinders, and 
a hydraulic cylinder, which is filled with 25J pints of oil. In recoil, 
the oil in the hydraulic cylinder is forced from one side of the piston 
to the other through small portholes. The area of these ports are 
calculated to make the resistance which the liquid offers, plus the re- 
sistance of the springs, such that the wheels will not jump from the 
ground when the gun recoils. In counterrecoil the oil is forced back 
through these small ports with the result that the return of the gun 
into battery is so eased and regulated that shock and consequent 
derangement of the aim is almost eliminated. To properly return 
the gun. to battery at high angles of elevation, the springs are assem- 
bled with an initial compression of approximately 1,500 pounds in 
each cylinder. 

061) 



162 




163 




164 

Tko carriage is equipped with a single trail, composed of two pressed 
steel flasks, and is anchored in the ground by a spade when in action. 
When traveling, the trail is supported by the carriage limber which 
may be drawn by either a truck or tractor. On account of the single 
trail the maximum elevation of the gun, without digging in the trail, 
is only 15. The allowable transverse movement is 140 mils, or 
about 8. 

The motorized equipment of each gun carriage, as indicated below, 
consists of a carriage limber, which supports the trail when traveling, 
and three caissons, which carry ammunition. 

4.7-inch gun and carriage, model of 1906. 
4.7-inch gun carriage limber, model of 1905. 
4.7-inch gun caisson, model of 1916 or 1917. 
The above materiel is entirely of American design and manufacture. 




LEFT FRONT VIEW OF CARRIAGE EQUIPPED WITH BAND BRAKES. 

Weights, dimensions, and ballistics. 

Weight of gun pounds. . 2. 688 

Total length , ..inches. . 134. 927 

Rifling Right hand, 1 turn in 50 calibers at origin to 1 turn in 25 calibers 
at 14.9 inches from muzzle, thence uniform. 

Weight of projectile, base fuzed shell and shrapnel pounds. . 60 

Weight of point fuzed shell do 45 

Weight of powder charge ounces. . 95 

Weight of cartridge case pounds.. 8 

Muzzle velocity (60 pound shell and shrapnel) ft. per sec . . 1, 700 

Muzzle velocity (45 pound shell) do 2, 050 

Maximum range at 15 elevation, of 45- pound shell yards . . 8, 700 

Maximum range at 15 elevation, of 60-pound shrapnel do 7, 550 

Weight of carriage, complete (without gun) pounds. . 5, 320 

Weight of gun and carriage, fully equipped do 8, 069 

Diameter of wheels inches. . 61 

Width of wheels do.... 6 

Height of axis of gun do 51.59 

Maximum angle of elevation (gun or carriage) degrees . . 15 

Maximum angle of depression (gun or carriage) do 5 

Amount of traverse mils... 140(7.8) 

Height of line of sight inches. . 53. 92 



1G5 




166 



4.7-INCH GUN AND CARRIAGE, MODEL OF 1906. 

The gun is of the built-up type, and consists of a tube, jacket, lock- 
ing hoop, and clip. The jacket covers the rear half of the tube, and 
projects beyond the tube at the rear to form the breech recess. The 




FRONT VIEW OF CARRIAGE EQUIPPED WITH TIRE BRAKES. 

jacket is equipped with a recoil lug on the underside for connecting 
the recoil cylinder. The clip is a short hoop near the muzzle and is 
fitted with guides to guide the gun in the cradle on recoil. 



TRIGGER rORK 
CXTRKTOR 
rIH6 HHNOLC 

TRIP LHrcH PLUNGCR 




SHAFT RCTHIN1NS COLL 

a*eccM BLOC* 

TRI6SCR SH/trT OCTCN 



TIKIM6 MHOLC SHHTT 




BREECH MECHANISM. 

The breechblock is of the interrupted screw type having four threaded 
and four plain sectors. It is operated by a handle which swings from 
left to right, turning and withdrawing the breech with one motion. 
An extractor is fitted for throwing out the shell case when the breech 
is opened after firing. 



167 

The firing mechanism is of the type known as a continuous-pull 
mechanism; that is, the mechanism is cocked and fired by the pull on 
the lanyard or by downward pressure on the firing handle located at 
the left side of the breech. 

The carriage is composed of the following principal parts: Wheels, 
axle, the cradle (for housing and supporting the recoil mechanism 
of the gun), trail, traversing and elevating mechanisms. 

The gun carriage is of the long-recoil type, in which the gun is 
permitted to recoil on the carriage to render the latter stationary 
under firing stresses. The recoil mechanism consists of an hydraulic 
cylinder filled with oil, placed parallel to the gun, and attached to 
the cradle The recoil cylinder controls the backward movement 
of the gun upon discharge, and the springs function to return the 
piece to battery position. 




FIRING MECHANISM. 



The recoil and counterrecoil mechanism is of the hydro-spring type, 
and consists of two parallel steel tubes (the spring cylinders) fitted 
into a frame and surrounded by rails which form the gun slides and 
the cradle. The recoil cylinder is fitted between these two. 

The piston and spring rods secured to the gun lug and recoil with the 
gun, while the spring cylinders and recoil cylinder remain stationary. 

The recoil is of the constant type, being 70 inches when the gun is 
fired at zero elevation, and is somewhat greater at higher angles, due 
to the action of gravity on the recoiling parts. The recoil cylinder 
uses hydroline oil as the buffer medium. Throttling is obtained by 
three throttling bars running lengthwise of the cylinder, which are 
of varying height to give a throttling effect with corresponding 
slots in the recoil piston. A counterrecoil buffer is fitted in the piston 
rod to take up the shock when the springs return the gun to battery. 



168 




169 

The trunnions on the cradle are mounted in bearings formed by a 
yoke which swivels in a pintle bearing provided at the front of the 
trail. 

Traverse is obtained. by means of a handwheel and screw mounted 
on the left side of the trail, which swings the yoke, it carrying the 
gun with it. A traverse of 70 mils on each side of center is possible. 

Tho piece is elevated by a double screw type of mechanism. The 
upper end is attached to the cradle and so raises and lowers it. 




FRONT VIEW OF CARRIAGE EQUIPPED WITH BAND BRAKES. 

The screw is operated through gearing by two handwheels, one on 
each side of the trail. From 5 degrees depression to 15 degrees 
elevation is obtained. 

The trail is of the solid type, made up of flasks of channel section. 
It houses the axle and carries the pintle bearing in which the top 
carriage, or yoke, swings. A tool box is fitted in the trail, and a 
seat is provided on each side of the trail for the cannoneers. The 
lunette transom is fitted about 27 inches from the rear of the trail, 
and carries a bearing that fits the limber pintle. A trail prop is 



170 



provided for supporting the trail when limbering. The spade can 
be released and folded up on the trail when traveling. 

A traveling lock is provided on the trail for locking the gun when 
traveling. The piston rod and spring rods must be disconnected 
before the gun can be drawn back far enough to lock. 




REAR RIGHT SIDE VIEW OF CARRIAGE. 



The wheels are 61 by 6-inch rubber tires, and are equipped with 
band brakes. Some of the older type of vehicles have steel tires 




ELEVATING AND TRAVERSING MECHANISMS. 

and are fitted with tire brakes. An armor plate shield is fitted to 
the carriage for the protection of the personnel. 

The sighting is similar to the 3-inch gun, model of 1902. 

The instruments for sighting and laying the piece include line 
sights, a rear sight, a front sight, a panoramic sight, and a range 
quadrant. 



171 




172 

The line sight consists of a conical point as a front sight and a 
V-notch as a rear sight. These are located on the jacket of the gun, 
and are useful for giving gen eral. direction to the gun. 

The rear and front sights are used for direct aiming. The rear 
sight is a peep sight mounted on range scale shanks on left side 




REAR VIEW OF CARRIAGE EQUIPPED WITH BAND BRAKES. 

of the cradle. The front sight consists of a pair of cross wires 
mounted in a ring about three feet ahead of the rear sight. 

The sight shank has a socket in which the standard United States 
panoramic sight may be mounted. 

On the right side of the cradle is mounted the range quadrant, 
which has in combination with it the angle of sight mechanism. For 
indirect fire the gunner on the right of the piece lays for range with 
this instrument, and the one on the left lays for direction only. 



173 




i_ uj 

$ V 



& & s 



^ in ^ 

< o < S g < < I < 

r^ruuur< u 

inuminj^in^ r? 




174 

Fixed ammunition is used with this gun; shrapnel and high ex- 
plosive shell being used. The base fuzed stell shell and the shrapnel 




FRONT VIEW OF CARRIAGE EQUIPPED WITH TIRE BRAKES. 

weigh 60 pounds. The point fuzed sheel weighs 45 pounds. Gas 
shells are also issued and are identical with the 45-pound steel shell. 



4.7-INCH GUN CARRIAGE LIMBER, MODEL OF 1905. 



The limber, a two-wheeled vehicle to which the trail of the car- 
riage is fastened, forming, with the gun carriage, a four-wheeled car- 
riage for the gun when traveling. 

The carriage limber is designed to be used with the connecting 
pole for attachment to a tractor and to support the trail in traveling. 
The limber is made of metal throughout, wood being used only in 
the spokes and felloes of the wheels. The principal parts are the 
wheels, axle, frame, top carriage, pole socket, and connecting pole. 

The top carriage is a steel casting, formed to accommodate "the trail 
of the 4.7-inch gun carriage, the trail resting on it when en route. 





FRONT VIEW OF LIMBER. 

The front end of the top carriage is provided with three rollers which 
rest and run on the top carriage rail; the rail edge being equipped 
with clips to prevent accidental dismounting. A spur located on the 
top carriage which enters the trail, holds the trail and top carriage in 
line. 

The wheels are 51 inches in diameter, 4 inches wide, and are rubber 
tired. The hubs are similar and interchangeable with those on the 
wheels of the carriage. The axle is hollow and is made from a single 
piece of forged steel. 

A bucket holder with straps is located on each side brace for car- 
rying four canvas watering buckets. 

18322& 20 12 (175) 



176 




177 

The doubletree, singletrees, and pole complete are omitted for 
motorized batteries and a competing pole is used in their place. 
The standard short pole with lunette is fitted for motor traction and 
for horss-drawn equipment the longer pole may be substituted. 

Weights and dimensions. 

Weight, complete, including spare connecting pole pounds. . 1, 750 

Weight of limber with gun and carriage, traveling position do 9, 818 

Diameter of wheels (rubber tired) inches. . 51 

Width of track do 60 

Free height under limber and carriage do 16. 8 



4.7-INCH GUN CAISSON, MODEL OF 1908. 



The 4.7-inch gun caisson is constructed upon the same general 
plan as the 4.7-inch caisson limber. The wheels, axles, pintles and 
bearings, lock bars, and most of the implement fastenings and chest 
parts of the two vehicles are exactly similar and interchangeable. 

The principle parts of the caisson are the wheels, axle, axle bearings, 
ammunition chest, pintle, connecting-pole socket, connecting pole, 
prop, apron, and brake. 

The flange-steel front plate and chest door (upper) of the limber 
are on the caisson replaced by armor plates, for the protection of 




RIGHT SIDE VIEW OF CAISSON. 

ammunition servers from small arms and shrapnel fire, An apron 
of armor plate is hinged to the bottom of the caisson chest and extends 
to within a short distance of the ground for the same purpose. This 
apron swings forward against the bottom of the ammunition chest 
to clear obstructions in traveling, and is held in that position by 
latches attached to the sides of the chest. 

The pole socket of the caisson is made longer than on the caisson 
limber, and is fitted with rollers which serve as wheel guards. The 
connecting body is made of steel tubing, its rear end is finished to 
fit the pole socket, and is provided with a seat for the rectangular 
key which secures the connecting p6le to the socket. A prop of 

(178) 



179 

steel tubing with a bronze foot is attached to the connecting pole for 
a support when the caisson is unlimbered ; when not in use the prop 
is swung up under the connecting pole and is held by chains. 

The beams of the road brake are hinged in brackets riveted to the 
^ chest front. The brakes are built up of flange and forged steel parts 
and carry cast iron shoes to bear against the wheel tires. 

Hangers for a spare connecting pole and a bracket for a spare key 
are provided on the chest. The ax, hatchet, lantern, and watering 
bucket fastenings are similar, and located like those on the caisson 
limber. The paulin on the caisson chest serves as a seat cushion 
and on either side of the chest handrails provide handholds for the 
cannoneers, when mounting or dismounting. 

The opening between the upper and lower intermediate plates 
011 the left side is utilized to carry a two-gallon oil. can. Of every 
four caissons, three carry oil cans containing lubricating oil, and the 
fourth, hydroline oil, the contents of each being indicated by a name 

plate. . : ' i 

Weights, dimension, etc. 

Weight of caisson limber, empty (without implements or ammunition), pounds. . 1, 821 

Weight of implements carried do 85 

Weight of ammunition carried do 2, 055 

Weight of limber, fully equipped and loaded do 3, 961 

Weight of caisson, empty (without implements or ammunition). do 2, 05J8 

Weight of implements carried (including spare connecting pole) do. 147 

Weight of caisson fully equipped and loaded do 4, 260 

Hounds of ammunition carried in caisson limber 28 

Rounds of ammunition carried in caisson 1 28 

Diameter of wheels inches. . 60. 

Width of track do. ... 60. 

Free height under caisson do 19. 55 

Turning angle degrees. . 80 



4.7-INCH GUN LIMBER, MODEL OF 1908. 



Tho limber is a two-wheeled vehicle provided with an ammuni- 
tion chest for the transportation of ammunition for the 4.7 inch gun. 

The principal parts are the wheels, axle, ammunition chest, pintle, 
pole socket, pole, doubletree, singletrees, and neck yoke. 

Tho wheels and the wheel fastenings are the same as, and are inter- 
changeable with, those on the carriage. The axle is hollow and of a 
single piece of forged steel. It is secured to the chest by axle bear- 
ings riveted to the sides of the chest and to the flanges of the inter- 
mediate plates. 

Tho ammunition chest is built up of flange steel and is divided 
into an upper and lower compartment by intermediate plates. Cor- 




VIEW SHOWING GUN CAISSON AND LIMBER, LIMBERED. 

responding holes in the middle and rear diaphragms are connected 
by conical brass tubes called connecting pieces, which are cut away 
on top to save weight. These connecting pieces support the front 
end of the cartridge case and serve to guide the projectiles. The 
chest doors close against the heads of the cases so that the cartridges 
are firmly held in position. Suitable clearances are cut in the flange 
of each cartridge pocket to enable the cartridge hook to get back of 
the rim of the case in withdrawing it from the chest. 

The doubletree is mounted upon a doubletree pin projecting up 
through a boss on the forward end of the pole socket. A limber 
prop is hinged to the pole socket. When traveling, the prop is drawn 
up to the rear and held by a chain. 

The pintle swivels 300 in the bearing, but is normally held in a 
vertical position by a spring bolted to the pintle bearing support. 

(180) 



181 

The right side of this vehicle is equipped with fixtures for holding a 
pick, hatchet, and pickax; while on the left side provision is made 
for a shovel. 

The paulin on the top of the chest is held in place by straps suitably 
fastened. Other fastenings on top of the chest are for a picket rope, 
an ax, and a limber blanket. On the front are attachments for a 
wrench and a pole prop. The cartridge hook for use in withdrawing 
the cases and projectiles from the chest is fastened on the left side 
of the caisson. A spanner for tightening the hub bands of the wheels 
is carried between the intermediate plates. 

The pole, doubletree and singletrees, and neck yoke arc standard 
and interchangeable with those on any limber of the battery. Double- 
tree chains attached to the chest body prevent excessive movement 
of cither end of the doubletree. 

The 4.7-inch gun limber, model of 1908, is only used in connection 
with the 4.7-inch gun caisson, model of 1908, both being of American 
design and manufacture. These vehicles are used with motorized as 
well as horse-drawn batteries of 4.7-inch gun materiel. 



4.7-INCH GUN CAISSON, MODEL OF 1916. 



The caisson, model of 1916, is a two-wheeled vehicle with an 
armored ammunition chest for the transportation of ammunition for 
the 4.7-inch gun. This vehicle is designed to carry 28 rounds of 




RIGHT FRONT VIEW SHOWING CHEST DOORS OPEN EXPOSING DIAPHRAGMS. 

the fixed type of ammunition. The body is suspended in such a 
manner that 7 rounds are carried below and 21 above the axle. 

The chest is built entirely of steel, but the upper door, rear plate, and 
an apron hung under the body are of armor plate for protection of the 
ammunition servers in the rear, from shrapnel and small-arms fire. 
The doors open to the front, and when closed bear on the heads of 
the shells. Suitable fastenings are provided on this chest for carry- 
ing the usual complement of tools and accessories, also brackets for 

(182) 



183 




184 

carrying fuze boxes on the outside of the chest. The chest provides 
scats for two cannoneers. 

This caisson is provided with an ammunition chest of sufficient 
size to carry either shrapnel or high-explosive steel shells. It is 
also equipped with fixtures for holding picks, shovels, and other 
tools on the outside of the ammunition chest. By removing the 
connecting pole, and adding double and singletrees, this vehicle may 
be transformed into a caisson limber suitable for horse traction. 




FRONT VIEW OF GUN CAISSON. 

The principal parts of the vehicle are the wheels, axle, ammunition 
chest, pintle, brake, connecting pole socket, and connecting pole. 

The wheels and wheel fastenings are the same as, and are inter- 
changeable with those on the carriage. The axle is fastened to the 
chest by axle bearings riveted to the chest sides. 

The body of the chest is of flange steel riveted together forming 
the top, bottom, and sides of the chest. The chest doors close 
against the heads of the cases so that the cartridges are held firmly 
in position. Suitable clearances are cut in the flange of each car- 



185 

tridge pocket to enable the cartridge hook to get back of the rim of 
the case in withdrawing it from the chest. The chest doors open to 
the front, the lower door being hinged to the bottom of the chest, 
the upper to the top of the chest, and by means of a lock bar, the 
doors are locked. 

The armor-plate apron is hinged to the bottom of the caisson, so 
that whoii traveling it may be swung backward against the bottom, 
where it is held by latches on the chest sides. 

The vehicle is equipped with a short connecting pole in front pro- 
vided with a suitable prop for holding the pole up when the caisson 
is at rest. At the rear is the standard pintle enabling other vehicles 
to be connected en train. 

On the tire brake models, brackets are riveted to the end of the 
chest. To these brackets are pinned the brake beams by the same 
kind of leverage system as on the carriage. The brake shoes are 
brought to bear on the tire by pressure on the brake lever, the brake 
lever and segment being on the left side of the vehicle. 

The brake band model like the tire brake, has the brake lever on 
the left side of the chest and is of the contracting band brake type. 
Pulling up on the brake lever, causes the brake bands to grip the 
drums bolted to the wheels. 

The top of the chest has provision made for carrying a picket rope 
and spare connecting pole, an ax, and straps for a paulin that also 
serves as a seat cushion. The left side carries the pick, mattock and 
hatchet; the right, a long-handled shovel, cartridge hook and pole 
socket key. On the back are riveted a bucket holder, lantern bracket 
and a foot rest. 

Between the intermediate plates in front, an oil can is carried on 
the right side, a fuze box on the left, and also a spanner wrench. In 
every battery, one caisson is provided with a hand reel containing 
one mile of wire as for the caisson model of 1917. See page 159. 

Weight, dimensions, etc. 

Weight of caisson, empty with implements or ammunition pounds. . 2, 565 

Weight of implements carried including spare constructing pole do 180 

Weight of ammunition do 2, 067 

Weight of caisson fully equipped and loaded do 4, 812 

Round of ammunition carried 28 

Diameter of wheels inches. . 61 

Width of track do 60 

Free height under caisson ..do.. 20.8 



4.7-INCH GUN CAISSON, MODEL OF 1917. 



The caisson, model of 1917, is a two-wheeled vehicle equipped 
with an armored ammunition chest for the transportation of ammuni- 
tion for the 4.7-inch gun. The two most important changes from 
previous models are: The substitution of a band brake for a tire 
brake, and a spring support for the ammunition chest. 

The principal parts of the caisson are: The wheels, axles, spring 
support, ammunition chest, brakes, pintle, and connecting pole. 

The wheels are 60-inch, steel tired with standard hubs and fasten- 
ers. The axle is a hollow single piece of forged steel. A distin- 
guishing feature of this caisson is the spring-supported chest. Suit- 
able brackets are provided on the chest and arms on the axle for 
carrying spiral springs to take up road shocks. 

The ammunition chest is built up of flanged steel, except the rear 
plate, apron and chest doors, which are of armor plate. The body 
of the chest is made of two sheets of flanged steel formed to shape 
and joined at the sides. Three vertical diaphragms with connecting 
pieces provided an even distribution of the load of ammunition. 
The upper door when raised is held at about a 60 angle. The lower 
door is made with an armor plate apron hinged to its top edge, so 
that when it is dropped, it forms, with the upper door and rear plate, 
an armor-plate protection. 

The road brake is of the contracting band brake type and is oper- 
ated from the right side of the chest by pulling up on the brake 
lever; this through a linkage causes the brake bands to grip the 
drums of the wheels. 

The connecting pole is attached to the caisson by a socket, the 
inside being tapered to accommodate the rear end of the connecting- 
pole, also the horse pole. 

Two foot rests of commercial flange steel are riveted to the upper 
chest door; these also serve as handles in opening and raising the 
door. A lantern bracket, and fastenings for holding a pick, shovel, 
lunette, and spanner wrench are riveted to the rear plate. At the 
top are riveted fastenings for holding an ax, connecting pole; also 
strap fastenings for the paulin and the caisson blankets. A car- 
tridge hook and hatchet fastenings are riveted to the left side of the 
chest. 

Of every four caissons three carry lubricating oil and one hydroline 
oil. One caisson in every battery is provided with a reel for caisson, 

(186) 



187 




188 

model of 1917, which is riveted to the top of the caisson and contains 
1 mile of field wire so arranged that the "talk" goes through all the 
wire. See page 159. 

By changing the connecting pole and adding the doubletree and 
singletrees this caisson is converted into a caisson limber. A standard 
pintle with a semiautomatic latch is provided at the rear. 

Weights and dimensions. 

Weight of caisson, empty, without implements or ammunition pounds. . 2, 053 

Weight of implements carried, including spare pole do 180 

Weight of ammunition do 2, 067 

Weight of caisson fully equipped and loaded do 4, 300 

Rounds of ammunition carried 28 

Diameter of wheels inches. . 60 

Width of track.. ..do.. 60 



5-INCH, 60-POUNDER, GUN MATERIEL (BRITISH.) 



The United States procured a number of batteries of 5-inch, GO 
pounder guns with the necessary accompanying vehicles from Great 
Britain. 

The materiel is of British design and manufacture throughout, 
and the units ceded to the United States include the gun, Mark I, 
mounted on a carriage, Mark II; the gun carriage limber, Mark II, 
the ammunition wagon, Mark II ; and the ammunition wagon limber, 
Mark II. 

The materiel was originally designed for horse transportation and 
thus is provided with poles and the necessary attachments for horse 




REAR LEFT VIEW OF CARRIAGE IN BATTERY. 

draft. By substituting the engine-draft connsctor in place of the 
horse draft poles, the materiel is converted into motorized batteries 
and may be drawn by tractors. When horse drawn, it is customary 
to divide the four vehicles into two trains, each having two vehi- 
cles; however, when the battery is adapted for motor draft, the four 
vehicles are drawn as ons train. 

The load of the gun carriage and limber is about as heavy as is 
practicable for horse transportation, although the British originally 
designed their 8-inch howitzer materiel, which is of greater weight, 
for horse transportation. 

The carriage is of tlie constant recoil type, the recoil mechanism 
being of the hydro-spring type, located above the gun. The recoil 
mechanism consists of two spring cylinders and one hydraulic cylinder 
filled with glycerine and water. 

The piston rod of the recoil cylinder and the rods of the two spring 
cylinders are connected to the lug on the breech ring of the gun and 
therefore recoil with the gun. 

(189) 



190 



nl 






ag 



I 8 



191 

Upon recoil of the gun, the liquid is forced past the piston head 
through a throttling groove or slot cut in the wall of the cylinder. 
The resistance offered by the action of the liquid in the cylinder, 
together with the resistance offered by the compression of the springs 
in the cylinders, controls and absorbs the shock of recoil, permitting 
the carriage to remain practically stationary upon the ground when 
the piece is fired. 

The energy stored up in the spring cylinders due to the compression 
of the springs during recoil is sufficient to cause the gun to return to 
the firing position. 

A hydraulic counterrecoil buffer is provided at the front of the 
hydraulic cylinder and acts as a cushion, thereby preventing the 
violent return of the gun to firing position. 




VIEW SHOWING TRAIL CONNECTED TO LIMBER. 

A range of 12,280 yards (11,230 meters) is possible, when firing a 
60-pound projectile with a muzzle velocity of 2,080 feet per second 
at the maximum elevation of 21^. 

The carriage is equipped with tractor wheels provided with inde- 
pendent wheel brakes. 

The trail is of the single unit type, being broadened at the spade 
end and equipped with a fixed spade for anchoring the trail to the 
ground. 

When traveling, the carriage is connected to the limber by un 
adjustable connecter. 

The carriage permits elevation from 5 depression to 21 $ elevation. 
The carriage permits traverse of 4 left and 4 right, when it is ele- 
vated at 16^ or less. At higher elevations the traverse is but 3 
right and 3 left, due to the interference of the trail with the gun at 
these elevations. 

18322820 13 



192 

Weights, dimensions, and ballistics. 

Weight of carriage and gun pounds. . 12. 09<i 

Weight of gun and brooch mechanism do. ... 4. 858 

Weight of carriage do 7, 238 

Weight of projectile do 60 

W T eight of powder charge do .... 9. 44 

Pressure of trail on ground do .... 920 

Length of gun inches. . L6S. 05 

Length, over all. of carriage and limber, traveling position, with gun but with- 
out limber pole feet. . 2S. 625 

Length, over all, of carriage and limber, traveling position, with gun and 

pole , feet. . 37. 5 

Length between axles, of carriage and limber, traveling position do. ... 13. 75 

Height of axis of gun from ground inches. . 51. 5 

Maximum elevation degrees . . 21. 5 

Maximum depression do .... 5 

Traverse (at elevation of 16 or less): 

Degrees right 4 

Degrees left 4 

Traverse (at elevation above 16): 

Degrees right 3 

Degrees left 3 

Range, maximum yards. . 12, 280 

Muzzle velocity, noi mal ft. per sec . . 2. 080 

Rifling, uniform 1 turn in 30 calibers. 

Diameter of carriage wheels inches . . GO 

Track, center line to center line of wheels do ... 63. 5 

Diameter of turning circle . . feet . . 54 



5-INCH, 60-POUNDER GUN, MARK I, AND CARRIAGE, 
MARK II (BRITISH). 



The gun is of the wire wound type and consists of two tubes, 
jacket, breech bush, breech ring, and several layers of steel wire. 
The inner tube extends the length of the barrel, the outer tube being 
shrunk upon it, extending over the rear of the inner tube to form a 
threaded bearing for the breech bush which receives the breech block. 
The jacket is fitted over the tubes and extends to the rear, having 
a threaded section on which the breech ring is received. Several 
layers of steel wire are interposed between the jacket and tubes, 
the jacket being shrunk over the wire. The breech ring is provided 
at the top with a lug, to which the recoil piston rod and the rods of 
the spring cylinders are secured, being the direct connection between 
the gun and recoil mechanism, and is provided with lugs at the right 
side which accommodate the breech carrier. . On either side of the 
j acket longitudinal pro] ections are provided, which engage and slide 
in corresponding slots in the cradle. 

The breech block is of the interrupted screw type, having threaded 
and slotted sectors. The breech bushing is threaded and recessed 
to correspond with the sectors on the breech block. The breech 
mechanism is so arranged that by one pull of the breech lever from 
left to right the breech screw is unlocked and the screw and carrier 
swung into loading position. After loading, one thrust of the same 
lever inserts the breech screw into position in the breech bush and 
turns it into the locked position. 

The breech screw is supported by the carrier, which pivots and is 
hinged to the lugs provided on the right side of the breech ring. 

The firing mechanism is of the "T" type and is fitted with a safety 
device which prohibits the firing of the gun until the breech is closed. 
Discharge is by means of a lanyard operated from the right side of 
the carriage. 

The carriage consists of the following major parts: Cradle, including 
recoil mechanism; top carriage; elevating and traversing mechan- 
isms; trail; brake gear; wheels and axle. 

The carriage is constructed on the long recoil principle, having 
practically a constant length of recoil at all elevations. The length 
of recoil is approximately 57 inches. The recoil mechanism is placed 
parallel with, and located above the gun, the gun sliding during 
recoil and counterrecoil in slides provided in the cradle. 

(193) 



194 

The recoil mechanism being of the hydro-spring type, utilizes two 
spring cylinders and one hydraulic cylinder, independent of each 
other, and held in relative position by the cradle. The cradle is 
cylindrical in form and incloses the breech end of the gun, and is 
provided with threaded holes at the front and rear for the reception 
of the spring and hydraulic cylinders, which are screwed into these 
holes. The three cylinders extend to the rear and engage suitable 
holes in the breech ring to which they are fastened by connecting 
pieces, the two spring cylinder rods being retained by nuts, and the 
hydraulic cylinder rod by an externally threaded collar which passes 
through the breech ring and engages the thread on the piston rod, 
the three rods recoiling to the rear with the gun. 

The trunnions of the cradle are received in bearings in the top 
carriage, which in turn is pivoted on the front end of the trail to 
permit traverse. 

Traverse and elevation is accomplished through the medium of 
handwheels located on the left side of the carriage. The elevating 




REAR RIGHT VIEW OF CARRIAGE. 

handwheel actuates a pinion meshing with a rack bolted to the 
cradle. The traversing handwheel operates a screw, one end of 
which is hinged on the top carriage, the other end engaging a nut 
which pivots on the trail. 

Traversing stops are provided on either side of the top carriage 
to limit the traverse to 4 right and 4 left, when the gun is elevated 
at- 16^ or less. 

The amount of traverse is indicated by a pointer fixed to the trail, 
which reads to a graduated scale on the rear transom of the carriage. 

The trail is of the solid type, being cut out at the front to give 
clearance to the breech of the gun during recoil, and at high eleva- 
tions. The front end of the trail is equipped with bronze brackets 
through which the axle Dasses. The trail has a bearing at the 



195 

forward section on which the top carriage rests and pivots, and 
through which the pivot pin passes, retaining the top carriage in 
proper position. Clips are provided on the trail which engage 
protrusions on the top carriage, preventing vertical movement of the 
top carriage when the gun is fired. Traversing stops are provided 
to prohibit traversing of more than 3 left and 8 right, when the gun 
is elevated above 16^. 

The rear end of the trail is equipped with a connector for limbering 
the carriage to the carriage limber. The connection is held in 
position by pins, and is provided with holes for adjustment. 

A spade of the fixed type is riveted to the rear end, and holds the 
trail in a practically stationary position when the gun is in action. 

A traveling lock is provided on the trail which engages the breech 
of the gun at degree elevation, when traveling. The lock is hinged 
to the inside of the trail members and swings down when the gun 
is in firing position. 

The wheels are of the tractor type, being provided with diagonal 
cleats riveted to the rims. The wheels are 60 inches in diameter 
and have tires 12 inches in width. 

A brake ring is provided on each wheel against which an internal 
brake shoe is fitted, which is operated by a handwheel at the front 
of the carriage. 

Sighting is accomplished by means of a tangent sight and foresight 
on the right side of the carriage, and by an oscillating sight and dial 
sight (panoramic sight) on the left side of the carriage. 

The tangent and foresight together form an open sight for the 
direct laying of the gun. 

The oscillating sight on which the dial sight is mounted is used 
for indirect laying; the oscillating sight being used for laying in 
elevation and the dial sight for direction. 

Ammunition of the separate loading type is used, being both 
explosive shell and shrapnel. The weight of each is 60 pounds. 
The propelling charge consists of 9 pounds 7 ounces of cordite. 
Normally these charges are not separate for zone fire, although 
special charges are sometimes made up for this purpose. 



5-INCH, 60-POUNDER, GUN CARRIAGE LIMBER, 
MARK II (BRITISH). 



The limber consists mainly of a steel frame, two steel chests, 
wheels, axle, and draft connections. 

The vehicle is designed for 2-horse, 4-horse, or tractor draft. 
When horse drawn, the front end of the frame is equipped with a 
wooden horse pole, which is retained in place by a pin passing ver- 
tically through the rail and pole, and is also equipped with two or 
four singletrees, as the draft may require. Chains, with the neces- 
sary draft connections, are also provided, and extend from two points 
on the frame to the forward section of the pole, thereby adapting 
the vehicle for additional horse draft. The necessary neck yoke 
bars are provided on the draft pole. 




FRONT VIEW OF CARRIAGE LIMBER. 

For 4-horse draft, the two outside singletrees are suspended from 
outriggers which are hinged to the main frame, and are steadied by 
stays extending back to the axle arms. 

For 2-horse draft, the two outside singletrees are removed, the 
stays disconnected, and the outriggers folded back and over the 
main frame, being held in the latter position by straps. 

The singletrees, when removed, are strapped across the center of 
the frame forward of the steel chests. 

For tractor draft, all the singletrees are removed and strapped to 
the frame, the horse pole being removed and replaced by the motor 
draft connector, which is pinned to the frame. 

(196) 



197 

The frame consists principally of four side rails, two inner and 
two outer, connected at the rear to the axle by flanges and pins. 
The front end is joined together by connecting plates, the frame 
being strengthened by diagonal stays. 

In the rear of the frame at the center, a pintle is provided, which 
accommodates the adjustable connector on the trail of the carriage 
in traveling position. The pintle is provided with a thumb latch 
which prevents accidental unlimbering of the trail connector. 

The steel chests are riveted to the main frame at the rear, on either 
side. The inner rear corners of these chests are formed diagonally 




REAR VIEW OF CARRIAGE LIMBER. 

to -allow clearance to the swing of the connector on the carriage, 
when traveling. 

The chests are of flanged steel, having lift lids which are hinged 
at the front side and are equipped with hasps, locks, and chains at 
the rear. The interior of each chest is fitted for carrying stores, and 
each is provided at the top with a tray which carries small stores. 
The left chest is constructed to carry the sights and attachments, 
together with a number of small tools, and one powder charge in a 
tin box. The right chest carries the clinometer, oil can, and other 
various tools and accessories, together with one powder charge in 
a tin box. 

Extending from the base of each chest toward the rear a steel 
bracket is provided on which one round of ammunition is carried. 



198 

The shell is held in a vertical position on this support hy a hronze 
bracket and a strap. 

Suspended below the frame at the rear, a wire net tray is provided 
for carrying drag ropes and lashings. 

Forward of the steel chests, on the top of the frame, a board is 
fastened, extending across the frame, and is equipped with friction 
clips for the accommodation of two rifles. 

The wheels provided are 60 inches in diameter, having steel tires 
6 inches in width. The outer end of the axle arms are equipped with 
drag washers to assist hauling. No brakes are provided on this 
vehicle. 

Weights, dimensions, etc. 

Weight without two projectiles pounds. . 2, 240 

Weight on limber pintle, traveling position do 641 

Weight on pole, carriage limber (at center tug hole) : 

Without two projectiles do 51 

With two projectiles do 39 

Diameter of wheels inches. . 60 

Track of wheels, center line to center line do 63. 5 

Length: 

With horse pole. do 186 

Without horse pole do 77 

Width: 

Over axle with dust caps do. ... 78. 5 

Outriggers extended do 110 

Outriggers folded do 65 



5-INCH, 60-POUNDER, AMMUNITION WAGON MARK II 

(BRITISH). 



The ammunition wagon (caisson) consists principally of a steel 
frame, ammunition chest, fuze lockers, brake gear, draft fittings, 
wheels, and axle. 

The wagon is constructed to carry 24 rounds of ammunition, 
24 powder charges in tin containers, and 2 fuze boxes. The exterior 
is fitted with fastenings to carry ropes, handspikes, also other tools 
and accessories. 




Q. 

u 




FRONT VIEW OF AMMUNITION WAGON. 

The ammunition chest is constructed of flange steel, having flange 
steel brackets on either side at the center, which extend below the 
chest, providing bearings which receive the axle. 

The interior of the chest is divided into a front section and a rear 
section, by a vertical steel plate, passing through the chest, parallel 
to the axle. Each section is divided by steel plates passing crosswise 
through the chest into three horizontal rows of compartments. The 
lower compartments contain 4 high explosive shell and 4 shrapnel. 
The middle row contains 2 high-explosive shell, 2 shrapnel, 2 

(199) 



200 

powder charges in tin containers, 1 fuze box containing 14 fuzes, 
and 1 empty compartment. The upper row of compartments 
contain 10 powder charges in tin containers. 

The powder charge containers, and the shell are retained in the 
proper position by quick release straps, and the shell are withdrawn 
from their respective compartments by means of the packing blocks 
which inclose the nose of the shell, and by the withdrawing straps 
provided. The withdrawing straps extend the length of the shell 
and are fastened to the nose blocks, and are also riveted to the com- 
partment plates, preventing their complete removal. When the 



: -*^ZlL^- - j^-^**-*^lll^XS^^-.-* =*- - - **-" *~ 




REAR VIEW OF AMMUNITION WAGON. 

shell is withdrawn about half its length, the withdrawing strap is 
slipped over the base of shell allowing the complete removal of the 
shell, while the packing blocks and straps are held in their respective 
compartments. The powder charge containers can be lifted out 
without the aid of straps. 

The front compartment is equipped with a steel door which is 
hinged at the bottom and swings downward when opened. The 
rear compartment is equipped with an armor-plate door hinged at 
its lower edge, and when opened hangs vertically downward. The 
front door when opened downward is supported by the footboard 



201 

in a horizontal position. Each door when closed is held in position 
by latches provided on the sides of the chests, which swing over and 
engage steel handgrips riveted on either edge of the door at the top. 

Extending above the chest at the front on either side, handrails 
are provided. The rails are constructed of steel and are provided 
with leather guards. The rails fit into small brackets riveted to the 
chest sides, and may be dismounted from tjie chest by removing 
the retaining pins. Three grip straps are also fastened to the upper 
front edge of the chest to assist the personnel when mounting the 
vehicle. 

Straps are provided with the usual fastenings, at the top of the chest 
to accommodate the soldiers' personal equipment, and also picket 
ropes, at the rear. At the front of the chest the fastenings accom- 
modate blankets, lamps, and tool cases. On either side of the chest 
fastenings are provided, the left side accommodating a saw in a leather 
case, and the right side a spanner wrench. 

The frame consists of two flanged sides connected by cross stays 
to the draft pole, which consists of two flange steel members extending 
back, the length of the vehicle. The outside rails are provided with 
flanges and holes through which the axle passes. The chest is 
mounted on the frame, the axle brackets on the chest corresponding 
with the flanges on the side rails, making a solid bearing for the axle, 
which is held in place by keys. 

Forward of the chest, across the side rails, a wooden footboard 
and platform is provided. Suspended below the footboard on either 
side, is a fuze locker, which provides carrying compartments for 
30 fuzes, 15 in each locker. Each locker is provided with a door, 
which swings downward when opened, arid each is equipped with a 
hasp and a pivot thumb lock. 

Suspended from the platform to the rear of the right fuze locker, 
a tin box, containing 3 pounds of grease, is strapped. 

The frame is provided at the rear with a steel prop which swings 
up to the right side of the frame and is retained in this position by a 
spring clip when in traveling position. 

Wire-net receptacles are suspended under the rear section of the 
frame on either side of the prop bracket. The receptacles provide 
space for canvas watering buckets and ropes. 

The draft pole, which is an extension of the center rail of the 
frame, is joined at its extreme forward end by a lunette, which engages 
the pintle on the ammunition wagon limber when in traveling posi- 
tion. A pole prop is also provided for supporting the draft pole 
when the wagon is unlimbered. The prop swings up to a horizontal 
position when the wagon is in traveling position. Attachments on 
the underside support a jointed draft pole and a handspike. 



202 



Tire brakes are provided for each wheel, the brake system being 
operated as one unit. The shoes which bear against the wheel are 
supported by brackets fastened to the side rails at the front. 

The shoes are operated by a crank located on the left rear side of 
the vehicle under the frame. The crank is connected to the shoes 
by rods supported on the frame. 

Wheels of the wooden type, 56 inches in diameter, having steel 
tires 3 inches in width, are provided on this vehicle. They are 
retained on the axle by means of an adjusting collar and linch pin. 




AMMUNITION WAGON AND AMMUNITION WAGON LIMBER, LIMBERED. 

The bearing is protected from dirt and other foreign matter by a dust 
cap which fastens over the end of the hub box. 

Drag washers are provided on each wheel to which ropes may be 
fastened to assist in the maneuvering of the vehicle. 

Weights, dimensions, etc. 

Weight of wagon, empty pounds . . 1, 732 

Weight of wagon, loaded and equipped do 3, 556 

Pressure of wagon pole on limber pintle, loaded do 98 

Pressure of wagon pole on limber pintle with two men on wagon, loaded .. do .... 196 

Height to top of handrail ' . . .feet. . . 5. 229 



Height, handrails removed do . . . 

Width, maximum do. . . 

Length of wagon do . . . 

Greatest projection beyond track of wheels , inches. 

Wheel track do. . . 

Diameter of wheels ... . . do . . 



4.416 

6.291 

9.708 

6.25 

63 

56 



5-INCH, 60-POUNDER, AMMUNITION WAGON LIMBER, 
MARK II (BRITISH). 



The limber comprises the frame with pintle; ammunition chest: 
I'u/c locker: draft fittings: wheels and axle. 

The limber is designed to draw the ammunition wagon by means 
of the pintle provided at the rear. The vehicle is e -pupped for 
2-horse draft. It carries 16 rounds of ammunition together with 
the necessary powder charges. Provision is also made to carry 
43 fuzes. 28 of which are carried in the ammunition chest, and the 
remainder in the fuze locker fastened to the top of the chest. Imple- 
ment fastenings are fastened on the exterior of the chest and foot- 




FRONT VIEW OF AMMUNITION WAGON LIMBER. 

board, and accommodate rifles, blankets, "and the customary tools 
and accessories. 

The chest is constructed of steel and is provided at the rear with 
three doors. The interior of the chest is subdivided by two steel 
plates into three main divisions, access to each being at the rear. 

Each division is separated by cross plates into four rows of com- 
partments, the lower two rows of each division being subdivided into 
smaller compartments to accommodate a total of eight high ex- 
plosive and eight shrapnel shells. 

The two upper rows of the two outside divisions are constructed 
to accommodate a total of 16 powder charges, each protected by 
tin containers. 

(203) 



204 

The two upper rows of compartments in the middle division accom- 
modate a tray for small stores, such as cotton waste, pins, pliers, and 
other small tools; and 2 fuze boxes, each containing 14 fuzes. The 
fuze boxes occupy the upper row of compartments. 

The powder-charge containers and the shell are retained in place 
in the chest by quick-release straps, and the shells are withdrawn 
from the compartments by withdrawing straps and blocks, identical 
with those on the ammunition wagon. 




REAR VIEW OF AMMUNITION WAGON LIMBER. 

A door is provided at the rear of the chest for each main com- 
partment. The two outer doors are of armor plate and have hinges 
at the bottom edges, and when opened hang down vertically from 
the chest. A small armor-plate apron is hinged to each door at its 
upper edge. The aprons hang vertically from the door when each 
door is opened, and form an extension toward the ground, thereby 
giving additional protection for the personnel serving the gun. 
When the door is in closed position, the aprons fold down over the 
outside of the door and are retained in position by latches fastened 
to the upper part of the chest, which engage steel hand grips riveted 
to the aprons. 



205 

The middle compartment is equipped with a steel door which is 
hinged at the upper edge, and when opened, rests over the top of the 
chest: The spring latches with thumb lift grips are riveted to the 
door which engage suitable latches on the lower edge of the chest 
when the door is in the closed position. Two small clips which extend 
over the edge of the side, at the lower sides, act as retainers for the 
outer doors when they are closed. 

In operation the middle door is first opened, thereby removing the 
clips which bear against the outside doors, allowing the outer doors 
to be swung open. In closing the chest the two outer doors are 
closed first. 

Handrails, protected by leather, are provided on either side of the 
chest, and extend above the chest. They engage suitable brackets 
riveted to the chest, to which they are fastened by pins. By the 
removal of the retaining pins, the handrails may be dismounted from 
the chest. 

The exterior of the chest is fitted with implement fastenings and 
straps, the front plate having spring catches for three rifles. Three 
grip straps are fastened to the upper edge of the chest at the front, 
to assist the personnel in riding on this vehicle. 

Three leather pockets, one on the rear middle door and one on 
either side of the chest, are provided for carrying fuze and limber 
keys. 

A wooden locker for carrying fuzes is fastened by steel straps to the 
top of the chest on the left side. The locker is equipped with a lift 
lid, hinged at the front and provided with a hasp and thumb lock at 
the front. The interior is constructed to carry 15 fuzes. Two 
blankets, which serve as a seat cushion, are strapped to the top of 
the chest at the front, and the soldiers' personal equipment is strapped 
at the rear. 

Each side of the chest has riveted thereto a steel bracket, which 
extends below the chest body, and is provided with an opening 
through which the axle passes. 

The frame which supports the ammunition chest consists mainly 
of two side rails, two middle rails, and the connecting cross rails. 

The middle rails are connected at the front of the frame to form a 
seat for the wooden horse pole. The outer rails converge slightly at 
the front, and with the middle rails form a support for the wooden 
platform and footboard. Two of the cross rails extend across the 
frame, directly beneath the edges of the chest, giving a solid support 
to which the chest is fastened. The other cross rail extends across 
the extreme front of the frame and is fitted with hooks for the support 
of two singletrees. A wooden horse pole, equipped with a neck yoke 
bar, is provided. 

Forward of the chest a wooden footboard and platform is fastened 
to the upper side of the frame. The boards have staples for the 



206 

accommodation of leather straps, which secure rope lashings, shovels, 
and other similar equipment to the footboards. 

On the under forward right side of the frame a -case is provided to 
carry a holo. On the left side of the frame, in a corresponding posi- 
tion, a case is provided, to carry a water brush. 

Suspended from under the wooden .platform, on the left side, is a 
box containing 3 pounds of grease. Under the right side of the 
platform, fastenings are provided to carry two cans containing 
lubricating oil. 

A pintle, which engages the lunette on the draft pole of the ammu- 
nition wagon, is provided in the frame at the rear. 

In each side rail at the rear a hole is provided which forms a bearing 
for the axle. The steel axle bracket on the sides of the chest corre- 
spond with these holes, and form a solid bearing for the axle, which 
is held in place by keys. 

Wheels of the wooden type, 56 inches in diameter, having steel tires 
3 inches in width, are provided. An adjusting collar and linchpin 
screws the wheel to the axle. Protection against the ingress of dirt 
and foreign matter is provided by a dust cap which fastens over the 
end of the hub box. 

Drag washers to assist in the maneuvering of the vehicle are pro- 
vided on each wheel. 

The wheels and axle of the limber are interchangeable with those 
on the ammunition wagon. No brake is provided on the ammunition 

wagon limber. 

Weights, dimensions, etc. 

Weight of limber, empty pounds. . 1, 416 

Weight of limber, loaded and equipped do 2, 632 

Weight of wagon and limber; empty - - -do . . 3, 148 

Weight of wagon and limber, loaded do 6, 188 

Weight of limber only, with wagon limbered up, empty do 1, 486 

Weight of limber only, with wagon limbered up, loaded .. do 2, 730 

Weight of limber pole at position of center tug hole with wagon limbered up, 

loaded, without men pounds . . 14 

Weight of limber pole at position of center tug hole with wagon limbered up, 

loaded, with 2 men on limber only y pounds . . 35 

Weight of limber pole at position of center tug hole with wagon limbered up, 

loaded, with 2 men on limber and 2 men on wagon pounds . . 25 

Length of limber with pole feet . . 14. 166 

Length of limber without pole do .... 5. 5 

Length of limber and wagon, overall do 22. 687 

Length between axles of limber and wagon do . . 8. 25 

Height of limber to top of handrails do 5. 666 

Height of limber, handrails removed do .... 4. 895 

Width of limber, maximum do 6. 291 

Wheel track of limber inches . . 63 

Diameter of wheels of limber do 56 

Diameter of turning circle of limber and wagon feet . . 23. 5 



155-MILLIMETER HOWITZER MATERIEL, MODEL OF 
1917 (SCHNEIDER). 



Recent experience indicated the necessity of artillery of larger 
caliber than the 75 millimeter, having a longer range and better 
characteristics, yet mobile enough to permit its use by combat divi- 
sions. This necessity led to the adoption of the 155 millimeter 
caliber corresponding to 6.10-inch artillery. The importance of this 
155-millimeter howitzer is evident when it is realized that it is the 
largest weapon at the present time that can be used by combat 
divisions, and is especially valuable for use against captive balloons, 
counter battery firing, and interdiction. 

The type of 155-millimeter howitzer carriage adopted is known by 
the French as the 155 millimeter Court Schneider, model of 1917, and 
by the United States as the 155-millimeter howitzer carriage, model of 
1918 (Schneider). The howitzers manufactured in the United States 




RIGHT SIDE VIEW OF CARRIAGE IN TRAVELING POSITION. 

are also distinguished from those made in France by the designation 
"Model of 1918." The American materiel differs from the French 
in having a straight shield instead of a curved one, rubber instead 
of steel tires, a slightly different firing mechanism, and several other 
minor changes. The howitzer is mounted on a carriage having a 
single trail composed of two pressed steel flasks. At the front end 
these are connected by the axle housing and at the rear by a fixed 
spade. The carriage embodies many ingenious features designed 
to reduce the weight and insure stability. 

The recoil mechanism is of the hydropneumatic type, the sleigh 
recoiling with the howitzer. In recoiling the liquid is forced from one 
side of the piston to the other though a variable orifice which grad- 
ually closes until the howitzer is brought to a stop. The return of 
18322820 14 (207) 



208 




209 

the howitzer into battery is effected by the expansion of the air com- 
pressed during recoil. The length of recoil . is practically constant, 
and in order to allow the howitzer to be fired at high elevations 
without digging in the trail, the trail is made of a curved shape. 




FRONT VIEW OF CARRIAGE IN BATTERY. 

By sliding transversely along its axle the howitzer is capable of 
traversing through a total angle of 6. Its maximum elevation is 
approximately 42. It fires a 95-pound projectile with a muzzle 
velocity of about 1,480 feet per second to a maximum range of about 
12,300 yards. Separate loading ammunition is employed. By the 
use of the reduced powder charges, shorter ranges are reached with 




SIDE VIEW OF CARRIAGE EN ROUTE. 

steep angles of fall and with less wear on the gun. Its life, before 
relining is necessary, is approximately 7,000 rounds. 

The entire equipment is motorized and the equipment for each 
howitzer includes a carriage limber, used when traveling to support 
the trail, three caissons or ammunition vehicles, and a number of 
ammunition, repair, and supply trucks. 



210 




155-MILLIMETER HOWITZER MATfiRIEL, MODEL OF 
1918 (SCHNEIDER). 

The 155-millimeter howitzer, model of 1918 (Schneider), is of the 
hydropneumatic long-recoil type, which may be used for direct fire, 
but was specially designed for indirect fire. On account of its high 
trajectory it is able to direct shells on targets inaccessible to field 
guns of limited elevation. 

This howitzer has given satisfactory results in actual service and 
has proven to be superior to other howitzers of similar caliber. It 
has a muzzle velocity of 1,480 feet per second and attains a maxi- 
mum range of 12,300 yards, the projectile weighing approximately 
95 pounds. 

A maximum rate of fire of four rounds per minute may be attained, 
but heating as well as difficulty of preparing and serving of ammuni- 
tion by the gun crew renders such rate impossible for any length of 
time, however. The normal rate of fire is two per minute. 

The howitzer is mounted on a sleigh and rigidly secured by a 
breech key and a holding-down band. The sleigh contains the 
recoil mechanism which permits long recoil and insures stability at 
low elevations. When the gun is fired, the sleigh recoils on bronze 
slides on the cradle, which is a U-shaped steel' plate and rests on the 
trunnion bearing of the trail. 

This howitzer may be elevated from zero to 42 by means of the 
elevating mechanism. The traverse is 52.5 mils to the right and left, 
the carriage sliding on the axle and pivoting on the spade, which 
prevents the carriage from recoiling when the gun is fired. The cus- 
tomary shield affords protection for the gunners from shrapnel and 
flying fragments. 

In traveling position the howitzer is retracted and locked to the 
cradle, the cradle locked to the trail, the spade revolved and secured 
to the bottom of the trail. The lower end of the trail rests on the car- 
riage limber, which is used to carry its proportionate share of the 
load of the howitzer and carriage in traveling position. The limber 
is equipped with a connecting pole for motor traction. The carriage 
and limber wheels are rubber tired and considered able to negotiate 
any roads suitable for field artillery. 

This materiel consists of: 

The 155-millimeter howitzer and carnage, model of 1918 

(Schneider) . 
The 155-millimeter howitzer carriage limber, model of 1918 

(Schneider) . 
The 155-millimeter howitzer caisson, model of 1918 (Schneider). 

(211) 



212 




213 

The howitzer, carriage, and limber are of the French design and 
were manufactured in the United States. 

The caisson is of American design and manufacture. This materiel 
is used with motorized batteries, and a full complement of tractors 
and trucks is provided for the transportation and service of the 
battery. 

The cart, model of 1918, and reel, model of 1909M1, described 
with the 75-millimeter materiel, are also used with this materiel. 

Weights, dimensions, ballistics, etc. 

Weight of howitzer, including breech mechanism pounds. . 2, 690 

Caliber inches. . 6. 10 

Total length f'o .. 91.0 

Weight of projei tile pounds . . 95 

Weight of maximum powder charge do .... 8 

Muzzle velocity of shell i'eet per second . . 1, 476 

Muzzle velocity of sharpnel: 

Minimum do. ... 666 

Maximum do. ... 1, 434 

Maximum range of shell yards . . 12, 250 

Maximum range of shrapnel do 10, 700 

Weight of howitzer and carriage, iully equipped pounds. . 7, 600 

Weight of carriage complete, but without equipment do 4, 729 

Diameter of carriage wheels inches. . 53 

Width of carriage track do 60 

Normal length of recoil do .... 51. 30 

Elevation to 42 20 

Maximum traverse (3 (52^ mils; right and 3 (52^ mils) left;. 

Weight of limber, completely equipped pounds. . 1, 440 

Diameter of limber wheels inches. . 42. 82 

Width of limber track do 61 

Turning angle of 155-millirneter howitzer, limber and carriage limbered 

degrees . . . 52 



214 




215 




155-MILLIMETER HOWITZER AND CARRIAGE, MODEL 
OF 1918 (SCHNEIDER). 



The howitzer is of the built-up type and consists of a tube and 
having a jacket shrunk over its rear half. The breech end is equipped 
with a counterweight which is fitted with leveling plates to be used 
with a gunner's quadrant when setting elevations. Below the breech 
recess is the bridle which couples the gun to the sleigh and on the 
forward end of the howitzer a holding down band also functions to 
secure the tube to the sleigh. 

The breech mechanism is of the plastic obturator type with an 
interrupted screw type breechblock. The breechblock is hinged at 
the right and by means of one motion of the breech lever can be ro- 
tated and swung clear of the breech. 

The forward mushroom-shaped head of the breechblock is equipped 
with a flexible asbestos ring known as the obturator pad. The gas 
check pad or plastic obturator is composed of a mixture of one part 
asbestos and three parts nonfluid oil, contained in a canvas cover- 
ing. The pad is protected by the front, rear and small split rings. 
A steel filling-in disk is placed between the gas check pad and the 
breechblock. On firing, the asbestos ring is compressed and acts as 
a gas check to prevent the leakage of powder gases back through the 
breech. The asbestos pad, by its shape, causes the split rings to 
spread when pressure is applied on the mushroom head. It has 
sufficient resiliency to resume its original form after firing. 

The firing mechanism is of the French percussion primer type. 
The primer is fired by means of the firing pin driven forward by a 
hammer operated by the lanyard. The firing pin is supported in 
the firing mechanism block, which is unscrewed each time a new 
primer is inserted. A safety device is used in connection with the 
firing mechanism block, which makes it impossible to unlock the breech 
while the block is in position, or to insert the block while the breech 
is unlocked. The firing mechanism block is interchangeable with 
those used in the following weapons: 

155-millimeter gun, model of 1918 (Filloux). 
8-inch howitzer (Vickers Mark VI and VIII^). 
240-millimeter Howitzer, model of 1918 (Schneider). 

The recoil mechanism is of the hydropneumatic long recoil type. 
With this howitzer the type of recoil is known as constant, i. e., the 
length of recoil is not shortened at high elevations. The sleigh 
contains the recoil mechanisms and serves as a support for the 

(216) 



217 




218 




219 

howitzer, being secured to it by the breech lug ana the nolding 
down band. On recoiling, howitzer and sleigh move on the cradle 
fastened to the trunnions of the carriage, the piston rods remaining 
stationary. 

A mixture of glycerine and water (boiled) is used in the recoil brake 
and to that mixture caustic soda is added for the counterrecoil mech- 
anism. The gas used in the counterrecoil mechanism may be either 
air or nitrogen. 

Nitrogen is always used when available, as it has no corrosive action 
on the mechanism. The energy of recoil is absorbed by the friction 
of the liquid while passing through the openings in and around the 
recoil piston and by the compression of the nitrogen in the cylinders. 
The howitzer is returned to battery by the energy stored in the com- 
pressed nitrogen which forces the liquid out and reacts against the 
counterrecoil piston. When in battery, the initial nitrogen pressure 
is approximately 485 pounds per square inch, which is sufficient to 
hold the howitzer in battery at all angles of elevation. Gages are 
provided to indicate both the quantity of liquid and nitrogen pressure. 
Suitable pumps are provided with the materiel for pumping in 
liquid and air. Cylinders of compressed nitrogen are carried to 
replenish the supply of nitrogen. 

The cradle is secured in the trunnions of the carriage and supports 
the sleigh during recoil. To the underside of the cradle are fastened 
two elevating arcs; thus the howitzer is elevated by means of the 
handwheel located on the left side of the carriage, and elevations from 
to 42 20' may be obtained. 

The traverse of the carriage is obtained by the traversing mechanism 
causing the carriage to slide on the axle, the trail pivoting on the 
spade. The movement is 3 each side of the center, or a total of 
105 mils. The movement is obtained by means of a traversing nut 
rigidly fastened to the axle, causing a traversing screw to travel 
carrying the carriage along the axle. The carriage travels along the 
axle on rollers mounted on Belleville springs. When the gun is 
fired, the springs are compressed and the carriage rests on the axle. 
A lock is provided for relieving the strain on the traversing and 
elevating mechanisms when traveling. Two traversing handwheels 
are provided, one on each side of the carriage. 

The wheels are of wood, 1,350 millimeters (53 inches) in diameter 
and are fitted with solid rubber tires. The carriage is equipped 
with a pair of brakes acting directly on the rubber tires. An armor- 
plate shield for the protection of the personnel against small arms 
and shrapnel fire is also provided. 

Sighting is accomplished by means of a quadrant sight, panoramic 
sight, and peep sight. 



220 




221 




222 

The quadrant sight, model of 1918 (Schneider), is mounted on 
the left trunnion of the carriage. It is used for laying the piece in 
elevation. The angle of site mechanism is combined with this sight. 
Mounted on the top of the quadrant sight is the United States pano- 
ramic sight for laying the piece in traverse. An extension bar is 
provided for use with the panoramic sight to enable the sight to be 
raised enough to see over the shield or other obstructions in direct 
aiming. 

The peep sight, used only in direct fire, or in emergency, may be 
mounted on the quadrant sight in place of the panoramic sight. 

Two complete sets of night-sighting equipment are provided for use 
when firing at night. When not in use these equipments are packed 
in cases provided for that purpose and carried on the carriage limber 
The night lighting equipment consists principally of a chest, an aiming 
lamp, an azimuth lamp, a portable lamp, and the necessary cables 
and fixtures. 



155-MILLIMETER HOWITZER CARRIAGE LIMBER, 
MODEL OF 1918 (SCHNEIDER). 



The 1 55-millimeter ho witzer carriage limber is a two-wheeled vehicle 
employed to support the trail of the carriage when traveling. This 
limber consists of a built-up steel frame mounted on wheels and axle. 
It has no chests and provides no seats for the personnel. 

The pintle is riveted to the extreme rear end of the frame and 
serves as a bearing for the lunette of the carriage when the howitzer 
is limbered. Additional support for the trail is provided by a trail 
rest riveted in front of the pintle and on which the fifth wheel of the 
trail bears. 

Hooks are provided for carrying a picket rope, and small boxes 
for carrying grease and the night lighting equipment are secured on 
the frame. 

A prop is provided on the front of the frame for holding the limber 
up when not en route. The standard short pole with the lunette for 
motor traction batteries is provided, or the long pole may be sub- 
stituted for horse-drawn equipment. 

The wheels are of wood construction, 1,240 millimeters (48.82 
inches) in diameter, with solid rubber tires. 

Weight and principal dimensions. 

Weight of limber empty pounds . . 1, 227 

Weight of limber completely equipped do. ... 1, 440 

Weight of limber and carriage, limbered do 8, 930 

Weight on ground under each wheel, with carriage limbered do 1, 380 

Weight of each wheel do 335 

Diameter of wheels inches. . 48. 82 

Width of track do 61 

Turning angle of limber and howitzer carriage, limbered degrees. . 52 

NOTE. The weight of this carriage limber equipped with horse pole is practically 
the same as with motor pole. 

(223) 
18322820 15 



224 



^- i ^ 



DOUBLE TREX CHAIN EYE 
LONGITb'DIMAL SUPPORT 
FRONT /WIL 
SUPPORT AUXILIARY BRACKET 

SUPPORT TE EAR 
SAFETY CHAIM 
SAFETY CHAJH CROSS BAR 
PLATE, 



-C-T L,_. - 



155 MM, HOWITZER CARRIAGE LIMBER. 

MODEL OF 1918 (SCHNEIDER). 

PLAN AND RIGHT SIDE VIEWS 




155-MILLIMETER HOWITZER CAISSON, MODEL 

OF 1918. 



The 155-millimeter howitzer caisson is a two-wheeled spring sup- 
ported vehicle for the transportation of ammunition. Normally it 
is a motorized vehicle, two caissons forming a train drawn by one 
tractor. However, by removing the connecting pole and substitut- 
ing the standard pole the front vehicle of the train can be converted 
into a horse-drawn caisson limber. Any caisson in the battery 




REAR VIEW OF CAISSON. 

except the caisson equipped with the hand reel can be so converted 
into a caisson limber. The caisson carries 14 complete rounds of 
ammunition and 2 extra powder charges for the 155-millimeter 
howitzer. 

The chest is made up of the lower and upper chest body and rear 
plate, which is of armor plate. The chest is divided into an upper 
and lower compartment, the opening between them forming a space 
for the axle, pole socket, pintle bracket, and houses the fuze box 
and oil can. 

(225) 



226 




227 

The upper compartment is arranged for the transportation of 
8 projectiles and 16 powder charges. Powder is served to the 
caissons in fiber containers, each containing 2 powder charges. The 
container is fitted with an air-tight joint metal cover and base. The 
lower compartment is arranged for the transportation of 6 projectiles. 
The upper chest door when closed forms a cover for the chest and is 
held open by door props. When open, this armor plate door serves 
as a shield for the cannoneers. 

The lower compartment is also provided with an armor plate door 
hinged to the bottom of the chest body, and has an armor plate 
apron hinged to its edge. When open, the lower chest door and 
apron hang down, forming a shield for the cannoneers. When 
closed, this door forms a cover for the lower compartment; the apron 
doubles back against the lower chest door and is latched in place. 

Both compartments are provided with loose diaphragms, by the 
use of which the caisson can be made available for transporting any 
of the following types of shells : 

155-millimeter common steel shell, Mark I; 
155-millimeter common steel shell, Mark II; 
155- millimeter sharp nel, Mark I; 
155- millimeter common steel shell, Mark IV; 
Semisteel shell, Mark XVII. 

Only one type of shell can be carried in the same compartment at 
one time. When carrying either common steel, gas, or shrapnel, the 
loose diaphragms are placed in position after the projectiles are 
inserted in the projectile tubes. When the doors are closed (carrying 
either common steel or gas shells) the door stiffeners bear against 
the bases of the projectiles, holding them in place. With shrapnel 
the edges of the flanged holes in the loose diaphragm bear against 
the rotating bands of the projectiles. When used to transport com- 
mon steel shells Mark IV the loose diaphragms are placed inside the 
body of the caisson next to the front diaphragms. When the doors 
are closed the door stiff eners bear against the bases of the projectiles, 
holding them firmly against the loose diaphragms. 

Foot rests, handrails, and grip straps are provided on the chest 
for the convenience of its personnel. The outside of the chest is 
provided with implement fastenings for the usual complement of. 
accompanying tools and accessories. Blanket straps are provided on 
top of the chest for carrying the blanket rolls of the battery person- 
nel; provision also is made on top of the chest for carrying the con- 
necting pole and on the rear for carrying the lunette and caisson 
prop when used as a horse-drawn vehicle. 

The caisson prop when down serves to support the front end of 
the caisson; in traveling it is swung up and held by the prop chain. 

The axle passes through the caisson between the upper and lower 
intermediate plates. Axle brackets are clamped on either end of the 
axle just outside of the chest, and rotation or lateral motion of the 



228 

chest is prevented by clamp screws and Belleville springs. The chest 
has a spring suspension similar to that of the 4.7-inch gun caisson, 
model of 1917, for the relief of road shocks. 

The caisson is provided with a brake mechanism of the band type. 
The brake drums are mounted on the hub boxes of the wheels and 
the band brakes lined with Raybestos. A brake lever secured to a 
bracket riveted to the caisson body, functions as a means by which 
the brakes may be applied. 

The caisson is usually equipped with the short pole for motor 
traction, but the pole socket is designed so that the long pole may be 
used when desired to use the vehicle as a horse-drawn limber. A 




FRONT VIEW OF CAISSON. 

standard pintle is fitted at the rear for the connection of the other 
vehicles. 

One caisson in each battery is equipped with a reel for caisson, 
model of 1917. This is a hand-operated reel for the transportation 
and handling of telephone wire. Se.e page 159. 

Weights and dimensions. 

Overall length inches . . 79 

Overall width do 78. 5 

Overall height do 67 

Weight without equipment (unloaded) pounds. . 2, 345 

Weight fully equipped (unloaded) do 2, 447 

Weight completely equipped and loaded do 3, 949 

Weight of reel caisson completely equipped and loaded do 4, 006 

Width of track inches. . 60 

Diameter of wheels do 60 

Turning diameter of two caissons feet. . 18 



155-MILLIMETER GUN MATERIEL, MODEL OF 1918 

(FILLOUX.) 



The type of 155-millimeter field gun adopted is known by the 
French as the'"G. P. F." (Grande Puissance Filloux), and by the 
United States as the model of 1918. This caliber, which corresponds 
to 6-inch artillery, is the heaviest mobile artillery, exclusive of the 
heavy howitzers and the railroad artillery. 

This monster weapon is of rugged design, combining mobility and 
power, and has a large horizontal training angle to render it suitable 
for the concentration of artillery fire for the destruction of strongly 
fortified points, such as armored batteries, etc.; thus no other avail- 
able weapon of equivalent caliber can be considered to rival this type. 
This piece, like the 155-millimeter howitzer, is especially valuable in 




TRAVELING POSITION (RIGHT SIDE). 

firing against captive balloons, counter battery firing, and inter- 
diction. 

The Filloux gun is mounted on a carriage having a split trail of 
box girder section; which is spread out when in action, the ends of 
the trail being firmly anchored by spades in the ground. The split- 
trail effect permits clearance for recoil at high elevations and allows 
a firing over a horizontal field of 60 and an elevation varying from 
to 35. 

Its muzzle velocity is about 2,411 feet per second, a rate of propul- 
sion that throws its projectile weighing 95 pounds, approximately 
17,700 yards, or a little more than 10 miles. 

The gun recoils in slides formed in the cradle which rests in the 
trunnions of the top carriage. The length of recoil is automatically 
controlled and varies with the elevation, while the counter recoil is 
pneumatic. The entire recoil mechanism is commonly called the 
recuperator and is supported on the carriage at its trunnions. When 

(229) 



230 







231 



traveling, tlio trail is closed up and the ends thereof are supported by 
a carriage limber provided with a steering gear brake, and is drawn 
by a tractor. In traveling position both carriage and carriage 
limber are supported on semielliptical springs to absorb all road 
shocks and vibrations. 




REAR VIEW OF CARRIAGE IN BATTERY POSITION. 

The life of the gun before relining becomes necessary is about 
3,000 rounds and maximum rate of fire is two rounds per minute. 
The entire equipment is motorized. A carriage limber, which 
supports the trails in traveling, accompanied each gun. Caissons 
are not used with these guns, the ammunition being carried in motor 
trucks or cargo carriers. 




CARRIAGE IN TRAVELING POSITION (REAR VIEW). 

155-millimeter gun materiel, model of 1918 (Filloux) consists of: 

155-millimeter gun and carriage, model of 1918. 
155-millimeter gun carriage limber, model of 1918. 

The above materiel is of French design and of both French and 
American manufacture. 



232 




233 

Weights, dimensions, ballistics, etc. 

Weight of gun, including breech mechanism pounds. . 8, 795 

Length of gun inches. . 232. 87 

Caliber do 6. 1042 

Muzzle velocity feet per second . . 2, 411 

Rifling: one turn in 2.989 caliber right hand uniform. 

Weight of projectile pounds. . 95 

Maximum range (Mark 11 1 shell at ;jr> elevation) yards. . 17, 700 

Weight of maximum powder charge pounds. . 25 

Weight of carriage only do 11, 065 

Weight of gun and carriage complete do . 19, 860 

Diameter of wheels millimeters. . 1, 160 

Width of track do 2, 250 

Height of axis of gun from ground do 1, 482 

Range of elevation degrees. . . to 35 

Maximum traverse do 60 

Weight of gun carriage and limber pounds . . 23, 050 

Weight of limber complete do 3, 190 

The distance from center line of carriage axle to center line 

01 limber axle, approximately millimeters. . 4, 500 



155-MILLIMETER GUN AND CARRIAGE, MODEL OF 

1918 (FILLOUX). 



The gun, models of 1918 and 1918 Ml is of the built-up type. 
consisting of a tube strengthened by a ring, jackets, hoops, and 
the muzzle bell. All details except the firing mechanism provide 
interchangeability of parts with the 155-millimeter (G. P. F.) guns 
of French manufacture. A recoil lug on the under side of the breed i 
ring provides means of attaching the recoil and recuperator rods. 
Bronze clips to serve as guides in the cradle are secured to the sides 
of the jackets. 




MAXIMUM ELEVATION OF GUN. 

The breech block is of the interrupted-screw type, having four plain 
and four threaded sectors. The breech mechanism is of the plastic- 
obturator type, having the forward mushroom-shaped head of the 
breech block equipped with an asbestos ring known as the obturator 
pad. Upon firing, this ring is compressed and acts as a gas check 
to prevent the leakage of powder gases through the breech. It lias 
sufficient resiliency to resume its original form after firing. The 
firing mechanism is of the French-percussion primer type described 
under " 155-millimeter Schneider howitzer/' page 216, and is inter- 
changeable with the guns enumerated therein. 

The cradle is a steel forging bored with three parallel cylinders for 
housing the recoil brake and recuperator, and is pivoted by trunnions 
in the trunnion bearings of the top carriage. On the upper side of 
the cradle are slots for the gun slides, and to its lower side the elevating 

rack is bolted 

(234) 



235 




236 




237 



The recoil mechanism is of the hydropneumatic variable recoil 
type. The larger of the three cylindrical bores in the cradle block 
contains the recoil mechanism; the two smaller ones, the parts of 
the recuperator mechanism. 

This mechanism consists of a piston and piston rod and a control 
rod. The piston rod is connected to the breech lug and, therefore, 
recoils with the gun. Grooves of variable depth are milled along the 
length of the control rod, controlling the flow of oil through the 
ports of the piston during recoil. The control rod assembles within 
the bore of the piston rod, and does not move longitudinally, but 
rotates. The amount of this rotating changes the area of the orifices 
through which the oil can pass. Its rotation is accomplished as the 
gun is elevated by means of an arm and gear sectors in such a manner 
as to shorten the recoil as the gun elevates. 




CARRIAGE IN FIRING POSITION. 



A replenisher or gravity tank is provided in connection with the 
recoil cjlinder which assures the recoil cylinders being full at all 
times and also takes care of any expansion of the oil due to heating. 
Its capacity is about 17 quarts. 

The recuperator mechanism consists of two connected cylinders, 
one containing the piston and piston rod which are attached to the 
breech lug, while the other contains a mushroom valve and a dia- 
phragm. The diaphragm separates the oil contained in the first 
cylinder and part of the second cylinder from the high-pressure air, 
which compels the return of the gun into battery after recoil. Nor- 
mally a small amount of oil must be between the valve and diaphragm. 
Oleonapthe is the liquid used in this recoil mechanism. The amount 
of oil in the recoil and recuperator mechanism is shown by indicators 
so that it can always be seen whether or not they need filling. 



238 




239 

The top carriage is a steel casting mounted on the bottom carriage, 
on which it pivots to traverse the piece. Belleville springs carry the 
weight of the gun when traversing, but on firing the springs compress 
and the firing stresses are taken on the bearing surfaces between the 
top and bottom carriages. 

The tipping parts are carried on the trunnions of the top carriage, 
which also houses the elevating and traversing mechanism and 
permits high angle of elevation for the cradle. 

The bottom, carriage is a steel casting suspended from the axle (in 
traveling position) by a heavy multiple leaf spring, j t supports 
the top carriage, houses the axle, and provides hinge connections for 
the trail. When firing the axle is unshackled from the springs and 
the bottom carriage bears directly on the axle. 

Traversing is accomplished by rotation of the top carriage on the 
bearing surface of the bottom carriage by means of a rack and train 




ACCESSORIES AND CATERPILLAR WHEEL SHOES. 

of gears which are operated by the handwheel on the left side of the 
carriage. A traverse of 60 30 right and 30 left is possible. 

Elevating is accomplished by a rack on the cradle operated through 
gears by the handwheel located on the gear box at the left of the top 
carriage. Elevations from to 35 are obtainable. 

The trail is of the split type and consists of steel plate beams of 
box section. Locks are pivoted at the forward end of the trails 
for securing them in the open position. When closed together they 
are clamped and attached to the limber. A traveling lock is provided 
on the trail for retaining the gun in retracted position. Two types 
of spade are provided, one for soft and one for hard ground. When 
traveling the spades are always removed from the trail. 

The wheels are of cast steel, each wheel having two solid rubber 
tires and are equipped with the usual band brakes. Caterpillar 
wheel shoes for traveling over soft ground are provided, which assem- 
ble over the rubber tires. They consist of 12 plates for each wheel, 
which give a broad bearing surface under the wheel. 
18322820 16 



240 




241 

The sighting equipment is exactly the same as that described under 
the 155-millimeter Schneider howitzer, except the difference in bracket 
as indicated on page 219. 

Ammunition used is of the separate loading type; the projectile 
weighs 95 pounds and the charge 25 pounds. Either shrapnel or 
high-explosive steel shell is used, as well as gas shells and other 
special ammunition. The propelling charge of smokeless powder 
is a sectionalized charge made up of two sections a base charge and 
one smaller increment. 

The fuses commonly used are the 31-second combination fuze for 
use with shrapnel and combining time and percussion elements the 
point detonating fuze Mark IV used with the steel high explosive 
shell, and the Mark II point detonating fuze used with gas shell. 



155-MILLIMETER GUN CARRIAGE LIMBER, MODEL 
OF 1918 (FILLOUX). 



The carriage limber is a two-wheeled vehicle designed to support 
and secure the rear ends of the trails and to provide a coupling 
attachment to the tractor when transporting the carriage. The 
principal parts are the wheels, axle, steering mechanism, frame, 
springs, and seat. 

The axle is very similar to the usual design of front axles of auto- 
mobiles. It is of I-beam section, having forked ends with axle arms 
pivoted therein, providing a means of steering. By means of a drag- 
link and steering lever pivoted at the center of the frame and con- 
nected to the steel pole steering is accomplished. 




FRONT VIEW OF LIMBER EN ROUTE. 

The frame or clamp for holding the gun trail in position is mounted 
on the axle by means of two semielliptical multiple leaf springs. The 
upper cross beam of this frame has bolted to it a seat for the brakeman, 
who operates the gun-carriage brake when en route by means of a 
lever acting through a wire rope. The wheels are identical with and 
interchangeable with the wheels of the gun carriage. 

Weights and dimensions. 

Weight complete pounds. . 3, 190 

Weight with carriage and gun do 23, 050 

Weight of carriage on limber (traveling position) do 6, 490 

Width of track (center to center of tires) millimeters . . 2, 250 

Free height under limber and carriage (traveling position) do 250 

Diameter of wheels do. ... 1, 160 

Height of seat cushion from ground (seat assembled on top of trails, traveling 

position) millimeters. . 1, 550 

Distance from center line of carriage axle to center line of limber axle (trails 

on limber) millimeters. . 4, 500 

(242) 



243 





244 





6-INCH GUN MATERIEL, MODEL OF 1917 (BRITISH). 



r n\c 6-inch gun materiel, model of 1917, is British throughout, 
being designed and manufactured in England. It consists of a 
6-inch gun, Mark XIX, mounted on an 8-inch howitzer carriage, 
Mark VII, known as the 6-inch gun carriage, Mark VIII A. This 
Mark XIX gun is of wire-wound construction, having a muzzle 
velocity of 2,350-feet per second and a range of 17,500 yards. 

The gun body is of steel and consists of tubes, a series of layers of 
steel wire, jacket, breech bush and breech ring. The breech ring is 
prepared for the reception of the breech mechanism and is provided 
with a lug on the under side for the attachment of the hydraulic 
buffer and recuperator of the carriage. 

The breech mechanism is operated by means of a lever on the right 
side of the breech. On pulling the lever to the rear the breech screw 
is automatically unlocked and swung into the loading position. 
After loading, one thrust of this lever inserts the breech screw and 
turns it into the locked position. The breech mechanism is similar 
to that used on the 8-inch howitzers both in design and operation. 

The firing mechanism is of the percussion type and is not inter- 
changeable with other British guns. The firing mechanism is 
designed for percussion firing, and is so arranged that the gun can 
not be fired until the breech screw is locked and the breech mechan- 
ism ]ever home. 

The only changes necessary on the 8-inch howitzer carriages (p. 268) 
for mounting this 6-inch gun are: The rear extension plug, which 
connects the gun to the recoil mechanism, is modified and the cut-off 
gear is set differently to shorten the recoil when in action. The 
firing platform and all of the accompanying vehicles of the 8-inch 
howitzer materiel are used. 

Ammunition of the separate loading type is used, both shrapnel 
and shell being issued. 

Weights, dimensions, and ballistics. 

Materiel of gun, steel wire wound. 

Length of gun inches. . 219 

Weight of gun with breech mechanism pounds. . 10, 248 

Weight of gun without breech mechanism do 9, 940 

Rifling, uniform one turn in 30 calibers. 

Weight of shell or shrapnel do 100 

Weight of powder charge (maximum) do 23 

Weight of powder charge (reduced) 15 pounds 7 J ouncea 

(245) 



246 




247 




248 

Maximum range: 

Full charge yards. . 17, 570 

Reduced charge do 16, 100 

Muzzle velocity: 

Full charge feet per second . . 2, 350 

Reduced charge do 2, 000 

Maximum elevation degrees. . 38 

Weight of carriage (only) pounds. . 12, 548 

Weight of gun and carriage (fully equipped ) do 22, 796 



7-INCH NAVAL TRACTOR MOUNT, MARK V. 



The 7-inch naval tractor mount, Mark V, is a mobile, track-laying 
field piece bearing a 7-inch, 45-caliber naval rifle. Projectiles 
weighing 153 pounds may be fired at angle of elevation varying from 
horizontal to 40, and at the maximum elevation the extreme range 
obtainable is 24,000 yards. 

The chamber diameter of the gun is 8.5 and the distance from the 
face of the tube to the base of the projectile is 54.39 inches. The 
volume of the powder chamber is 3,369 cubic inches. The maximum 
charge consists of 60 pounds of smokeless nitrocellulose powder, 
which produces the maximum service pressure of 17 tons per square 
inch. Under these conditions a muzzle energy of 8,315 foot-tons is 




CARRIAGE AND LIMBER IN TRAVELING POSITION (FRONT VIEW). 

imparted to the 153-pound projectile, the muzzle velocity being 
2,800 feet per second. 

The re ; coil mechanism is of the hydraulic type; the gun being re- 
turned to battery by a pneumatic counterrecoil system. The recoil 
'system consists of a simple hydraulic brake, the energy of recoil is 
absorbed through a distance of 32 inches by forcing a mixture of 
glycerine and water through orifices of gradually decreasing diameter 
cut in the head of a piston operating in the recoil cylinder. 

The method of reducing the size of the orifices is interesting. The 
recoil piston has holes bored through it to allow the liquid to pass 
from one side to the other when the piston starts to move back when 
the gun is fired. Tapered throttling rods enter the holes in the pis- 
ton head, and as the piston moves back the size of the orifice is grad- 
ually diminished. The area of the orifices is so calculated that a 
constant retardation is given to the gun, and it is brought to rest at 
the end of the stroke. 

(249) 



250 

The counter-recoil mechanism adopted on this mount is similar to 
the counterrecoil mechanism of the French type, as used on 155- 
millimeter guns. In this type of mechanism when the gun is fired, 
a piston attached to the gun yoke moves backward in an air-tight 
cylinder containing air at a pressure of several hundred pounds per 
square inch, still further, compressing the air. The air pressure 
acting on the counterrecoil piston when the gun has reached the end 
of the recoil brings the gun back into battery or firing position. 

The counterrecoil system which is used on this mount is located on 
the top of the gun, and has been changed into a combination of three 
cylinders, connected at the lower end by a bronze head. The piston 
attached to the yoke operates in the central cylinder. The system 




REAR VIEW OF CARRIAGE. 

of liquid packing is retained but simplified and the entire system is 
made up of shapes and materials easily secured and is well adapted to 
American machining methods. 

A traversing gear, incorporated in the carriage trail, permits of 
limited training either side of the center line. When a greater range 
of training is desired, the trail is either shifted on the ground or the 
carriage is mounted upon a firing platform which provides for training 
through a firing angle of 60. A shell-loading tray, which rests 
on the carriage trail, is used to load shells into the breech. 

The elevating gear consists of a simple combination of a handwheel, 
worm gear, rack and pinion. The sighting arrangements for the gun 
consist of a standard panoramic field sight fitted to a bracket at- 
tached to the gun carriage. 



251 

The track layer, which is of the double-tread caterpillar type, is 
designed to carry the mount over practically any kind of ground 
likely to be encountered in service. The proportions of the chain 
tracks are such as to produce a pressure of about 14 pounds per 
square inch upon the soil during transportation, which is approxi- 
mately half that exerted by a horse. The track layer also serves as a 
stand or foundation for the mount during action. 

A caterpillar tractor is used to draw this vehicle from one position 
to another. A limber hooked between the mount and the tractor 
supports the trail during transit; during action the limber and the 
tractor are withdrawn from the immediate field of danger. 

The limber wheels are carried on taper axles and are equipped with 
grease cups for lubricating purposes. A pintle and lunette are pro- 
vided on the axle in case it is desired to attach an ammunition or 
supply trailer for transportation. The limber is connected to the 




LEFT SIDE VIEW OF CARRIAGE IN BATTERY. 

mount by means of a swivel pole end which is pivoted on the limber 
connection of the trail. 

The firing platform provides a durable and substantial foundation, 
adaptable to various soil conditions and light enough to permit of 
easy and convenient transportation. The firing platform includes a 
forward table, upon which the track layers rest, and a rear thrust 
beam to which the trail is secured by suitable pins. The rear thrust 
beam is made in two sections, which, when combined, provide for 
training through an arc of 60. One section may be used alone if 
desired. Training is accomplished by shifting the trail around the 
arc of the platform to the set of pin holes nearest the desired angle. 
Accurate adjustments in training are made with the traversing gear. 

The 7-inch naval tractor mount is so designed that its weight is 
almost entirely supported by the track layers, but a small percentage 
of the weight being carried on the trail. When the mount is being 
pulled along an upgrade of appreciable slope, the center of gravity 



252 

is shifted and the weight of the gun may have a tendency to throw 
the trail in the air. 

To preclude any such occurrence, eyebolts are secured to the gun 
yoke, which are used to draw the recoiling parts back sufficiently 
to bring about equilibrium. 

Track grousers may be bolted to the track shoes when there is 
likelihood of the mount slipping sidewise during transport on hill- 
sides. In an actual road test this gun was pulled over rough ground 
and proved able to negotiate any ground over which the tractor itself 
was able to operate. Obstructions were mowed down, and yet the 
entire weight of the gun was so evenly and well distributed that no 
damage was done to roads negotiated. The mount functioned per- 
fectly, remaining steady on the point of aim during continued firing. 
The caterpillar treads, locked in position by the brake, were as steady 
as a concrete foundation. 



7-INCH GUN MARK II AND CARRIAGE MARK V. 



The 7-inch, 45 caliber, naval rifle is built up of a tube, hoops, and 
locking rings. When erosion destroys the effectiveness and accuracy 
of the gun it may be rebuilt by boring out the tube and shrinking in 
a conical nickel-steel liner. The gun, without the breech mechanism, 
weighs 12.81 tons, while the weight of gun and breech mechanism is 
28,700 pounds. The rifling is right hand of hook section and consists 
of 28 grooves and lands, having an increasing twist from zero at the 
origin to one turn in 25 calibers at a point 22 inches from the muzzle. 
The remainder of the twist is uniform. This gun is the heaviest and 
hardest hitting gun for which a mobile lield mount has been requested 
bv our Army. 




CARRIAGE AND LIMBER IN TRAVELING POSITION (REAR VIEW). 

The carriage, which supports the gun is a structural steel frame- 
work built up of standard shapes, consisting essentially of two steel 
trunnion bearing plates cross braced at each end to form a single 
unit with a central well into which the gun recoils. These side 
girders are riveted to the carriage trail, the carriage and trail forming 
a rigid unit, are supported on the carriage axle which turns in hubs 
mounted in the truck frames of the track layer. 

On the left-hand side of the carriage is arranged the mechanism 
for elevating and depressing the gun. The traversing gear, which 
provides means for training 2 either side of the center line, is incor- 
porated in the rear section of the trail. This gear consists of a steel 
plate resting on the ground underneath the trail: a worm shaft oper- 

(253) 



254 



ated by ratchet wrenches shifts the trail with reference to the plate 
and enables the gun to be accurately trained. 

Navy guns do not carry the trunnions attached directly to the gun, 
but are turned to a smooth surface on the outside. The cylindrical 
gun slide, on which the trunnions are attached, carries the gun; the 
trunnion seats are placed at the upper end of the carriage. The 
recoil and counterrecoil mechanisms are also attached to the gun 
slide, operating through pistons atttached to the yoke. The gun 
runs in and out of the gun slide when recoiling, bronze liners being 
fitted to the inside of the slide to enable this to take place easily. 
The trunnions of the gun are mounted sufficiently high so that at 
maximum angles of elevation only a shallow trench need be dug to 
permit clearance for the recoil of a gun. 




TOP CARRIAGE AND AXLE DETAILS. 



The elevating arc segment, meshing with the pinion of the eleva- 
ting mechanism, is bolted to a pad on the left-hand face of the slide. 
The teeth of the arc are cut on a pitch circle concentric with the 
trunnion centers to permit of a 40 movement of the slide in a ver- 
tical plane, starting from horizontal. The upper and lower extremi- 
ties of the arc are fitted with limiting stops to prevent j amming. 

The hydraulic brake. The energy of recoil is checked and dissipa- 
ted by means of a hydraulic brake mounted on the bottom of the 
slide. This mechanism is made up of a piston operating in a cylinder 
filled with liquid and rigidly fixed to the slide. The piston is attached 
to the gun yoke by the piston rod which passes through a stuffing 
box in the rear end of the cylinder. Two orifices are provided in 
the piston head for throttling rods w^hich are arranged longitudinally 
in the cylinder. In battery, all the liquid is in rear of the piston. 
As the piston recedes during recoil, the liquid is forced around the 
throttling rods through the orifices in the piston to the forward end 



255 

of the cylinder, dissipating the erffergy through the frictional heat 
generated. The cross section of the throttling rods, around which 
the liquid must flow in passing through the orifices, is such that a 
pressure approximately uniform is exerted upon the liquid throughout 
the period of recoil. The length of recoil is 32 inches. 
. Incorporated in the cylinder head is a counterrecoil chamber into 
which the recoil liquid flows during recoil. When the gun is brought 
back to battery by the counterrecoil mechanism, its momentum is 




ASSEMBLED VIEW OF HYDRAULIC BRAKE. 

checked through the action of a counterrecoil plunger, mounted on 
the forward face of the piston, as it enters the chamber and forces 
the liquid back into the cylinder through the orifice between the 
plunger and the plunger bushing screwed into the mouth of the cham- 
ber. This action takes place during only the last 14 inches of coun- 
terrecoil stroke. 

The liquid used in the hydraulic brake consists of a mixture of 4 
parts glycerine and 1 part water, by volume. This liquid is poured 
into the cylinder through a filling hole on the right-hand side of the 
cylinder head. 

18322820 17 



256 



The upper portion of the cyliiuter head is arranged to form an ex- 
pansion chamber to provide for the expansion of the liquid which 
results from the f fictional heat generated in the cylinder. When 
expansion of the liquid takes place with continued firing, the increased 
volume of the liquid simply compresses the air in the expansion 
chamber instead of acting to prevent the return of the gun to battery. 
To assure the presence of a definite amount of air in the expansion 
chamber at all times, the filling hole is fitted with a tube which extends 
down into the chamber and traps the desired volume of air when 
the cylinder is filled. 

Counterrecoil system. Energy to return the gun to battery and to 
maintain it in that position at all angles of elevation is obtained by 
means of a pneumatic counterrecoil system, mounted on the top of 




VIEW OF AXLE MOUNTED IN TRACK LAYER. 

the slide. A piston, operating in an air cylinder and connected to 
the gun yoke by a piston rod, serves to compress the air within the 
cylinder when the gun recoils. At the end of recoil, the compressed 
air acts upon the piston to return the gun to battery. On either side 
of the air cylinder and connected with it through a port is an air tube 
which serves as a reservoir. 

Since it is necessary for the counterrecoil system to support the 
weight of the gun and breech mechanism against gravity, the system 
is charged initially with air at 300 pounds per square inch, gauge pres- 
sure. This pressure assures the proper functioning of the counter- 
recoil mechanism at angles of elevation up to approximately 34. 
It is apparent that the factor of gravity decreases with the angle of 
elevation and hence less pressure is required to bring the gun to bat- 
terv when it is fired at angles near horizontal. 



257 

When charged to 340 pounds pressure, the mechanism will func- 
tion properly at all angles; however, if the cylinder should be charged 
only to, say, 225 pounds, the mechanism may be relied upon to return 
the gun to battery at angles of elevation up to 23 or 24. To insure 
return of the gun to battery when firing at angles above 34, air 
cylinders should be charged in accordance with the instructions, and 
to prevent breakage of the gauge glass and to preserve the accuracy 
of the instrument, it is recommended that the pressure gauge be 
removed before firing. 

The elevating gear train from the rack on the slide to the handwheel 
on the left side of the trail is made up of a pinion and shaft in mesh 
with the elevating arc. One turn of the elevating handwheel moves 
the gun 56' 17" in elevation or depression. 

The axle, a steel forging extending across the width of the carriage 
is supported in the track layer by a hub bracket which in turn is 
carried by the structure of the girder on which the sprocket and truck 




L 



SIDE ELEVATION OF TRACK LAYER. 



wheels are mounted. This bracket is held by oscillating bearings 
and is spring supported so that the caterpillar may adjust itself to 
any unevenness in the road when the gun is in motion. When the 
gun is placed in firing position, the springs are taken up by means 
of holding down screws in order that the mount may keep steady on 
the point of aim while firing. 

The function of the hub springs is to impart to the mount a degree 
of resiliency during transit. However, when firing, resiliency in the 
mount is undesirable and often dangerous, thus before firing the 
springs are compressed until the hubs bear directly upon the truck 
frames. This is accomplished by means of adjusting screws screwed 
down on the hub bearing blocks until the springs are compressed and 
the hubs rest solidly upon the truck frames. 

The trade itself consists of an endless belt of cast steel links connected 
by hardened pins, each link carrying a corrugated forged-steel plate 
which makes contact with the ground. The plates overlap when 
horizontal so that a continuous surface is presented. To prevent the 



258 

corrugated surface of the tread from slipping in soft ground, de- 
tachable grousers are provided. 

The track links run over a large idler wheel, a sprocket wheel, 
seven truck rollers, and four track rollers on each caterpillar track 
layer. The sprocket wheels carry but little of the load except when 
the gun is descending a grade or when the brake is applied to the 
mount. For smooth running and reliability, roller bearings are fitted 
in the truck and idler rollers, the ends of the rollers being closed by 
steel plates to prevent the entrance of dirt when the mount is hauled 
through mud, sand, or soft earth. A brake is provided to permit 
control of the mount when descending hills and also to lock the cater- 
pillar in position when the gun is set up for firing. The brake con- 
sists of a toggle joint operating on the rim of one of the sprocket 
wheels, the tension applied being controlled by an adjustable spring. 




CARRIAGE IN BATTERY POSITION, SHOWING MAXIMUM ELEVATION OF GUN. 

Simple as the brake is it has been exceedingly satisfactory in opera- 
tion in controlling the heavy mount on steep grades and in checking 
any tendency of the mount to move on firing. 

The track is carried around two track idler wheels which are pro- 
vided with bearings mounted on the extremities of the track frame. 
The aft idler wheel bearings are so mounted that they may be moved 
backward or forward as necessary to adjust the tension and to take 
up wear on the links and shoes. 

Friction brakes operating against the forward idler wheels are 
mounted on the truck frames. These brakes are of the spring release 
type and are applied by means of handwheels functioning through 
yokes and levers to the brake shoes. 

The quadrant sigJit (Schneider} is mounted on the left trunnion of 
the carriage both in traveling and in action. 



8-INCH HOWITZER MATERIEL (VICKERS). 



Success has been obtained with the 8-inch howitzer artillery for 
preliminary bombardment which precedes an infantry attack. This 
caliber is mobile in a sense, but there are limits to its mobility, for 
there comes a time when its advance must stop. When these 
howitzers have to be transported over land full of huge craters r 
with the roads entirely destroyed, the country encumbered with 
all kinds of debris and frequently reduced to a sea of mud, it can be 
easily seen why a successful "push" usually nets a considerable 
gain in captured artillery. If the trenches give way, it is almost 
impossible to get the heavy howitzers away quickly enough to save 




CARRIAGE IN BATTERY POSITION. 

them from being captured by the enemy. Thus, by mobile artillery 
is meant that which can be moved around essentially as part of the 
infantry. 

The howitzer, being comparatively thickset and short when com- 
pared with a gun of the same .caliber, is capable of greater angle of 
elevation than the same caliber of gun. The gun is primarily 
intended for attacking troops, while the chief aim of the howitzer 
is to destroy incumbrance such as trenches, barbed wire, pill boxes, 
and the like. A shell that travels from the howitzer ascends at a 
high angle and drops almost vertically. The explosion of a shell so 
fired is much more effective than one that is fired with only a slight 
elevated trajectory, as in the case of the field gun. 

(259) 



260 




261 

The 8-incli howitzer, being mounted on a wheeled carriage and 
not having to he disassembled for transportation, is much more 
mobile than the 9. 2-inch or 240-millimeter howitzer. This howitzer 
when set up ready for firing rests on and is braced upon a firing plat- 
form, which is transported on a two-wheeled wagon, the wagon being 
attached to the howitzer carriage and drawn as part of the unit 
with the carriage and limber by a tractor. On reaching the spot 
selected for position the firing platform is buried flush with the 
surface of the ground, furnishing a steady emplacement from which 
to fire. 

The 8-inch howitzer materiel is called the "Vickers" model of 
1917, of which there are in use two types, the Mark VI and Mark 
VII. The main differences between the Mark VI and the Mark VII 
being that the former has a lower muzzle velocity and consequently 
a shorter range than the latter, also that the Mark VII has a barrel 
of the "wire wound" construction, whereas the Mark VI type is of 
the "built up" construction. The Mark VII is also longer and heavier 
than the Mark VI. 

The Mark VII has lately been superseded by a Mark VIII^, the 
difference between the two being that the powder chamber walls of 
the Mark VII proved to be too thin, while the Mark VIII^ overcomes 
this defect by having thicker powder chamber walls. Due to the 
fact that the Mark VIIIJ howitzer has a greater muzzle velocity, 
and consequently a greater maximum range than the Mark VI by 
some 15 to 20 per cent, the former is the preferred type. 

The life of the howitzers before relining is necessary varies greatly. 
'Hie number of rounds they are capable of firing before the lining 
becomes badly worn depends on whether light or heavy propelling 
charges are used. The use of light propelling charges and greater 
trajectory elevation to get the desired range is recommended rather 
than heavy charges and low elevation. From information based on 
actual experience the average life of the 8-inch howitzer, Mark VI, 
is 7,800 rounds, while that of the Mark VHIi is 3,000 rounds. 

Comparative table of weights, dimensions, and ballistics for 8-inch hoivitzers, Marks VI 
and Vlin and 6-inch gun, Marie XIX. 







Mark VI 
howitzer 
(Mark 

VT 


Mark 
VIII* 
howitzer 
(Mark 


Mark 
XIX 








VII 


VIII-A 








carriage). 


carriage). 


Weight of howitzer or gun, including breech mechanism.. 
Weight of gun or howitzer without breech mechanism 
Total length of howitzer or gun 
Length of howitzer or gun 


.pounds.. 
do 
..inches., 
calibers 


6,552 
6,132 
127.6 
15 9 


7,730 
7,310 
148.3 
18 5 


10,248 
9,940 
219.22 
36 5 


Distance to center of gravity from breech, unloaded . . 


inches 


42.6 


50.5 


71 95 


Distance to center of gravity from breech, loaded 


do 


42 3 


50 6 


71 65 


Length of bore. 


do 


117 7 


138 4 


210 


Length of bore 




14 7 


17 3 


35 


Length of rifling... 


..inches.. 


102. 11 


99.52 


170. 75 



262 




~ * 






263 



Comparative table of weights, dimensions, and ballistics for 8-inch howitzers, Marks VI 
and VIII\ and 6-inch gun, Mark XIX Continued. 







Mark VI 
howitzer 

(Mark 
VI 
carriage). 


Mark 
VIIIJ 
howitzer 
(Mark 
VII 
carriage). 


Mark 
XIX 

gun 
(Mark 
VIII-A 
carriage). 


Number of grooves 




48 


48 


36 


Twist (uniform) 


R. H 


Iinl5 


Iin25 


lin 30 


Travel of projectile in piece 


inches.. 


104. 96 


102 72 


174.0 


Weight of projectile 
Weight of powder charge 


pounds . . 
do 


200 
10.75 


200 
17.5 


100 
23.0 


Max imum powder pressure . . . 


...do.... 


30,250 


30,240 




Muzzle energy 


foot- tons 


2 345 


3,228 


3,308 


Muzzle velocity . 


feet per second. . 


1,300 


1,525 


2,350 


Length of recoil 


inches. 


60-24 


52-24 


42-20 


Maximum elevation 


degrees. . 


50 


45 


38 


Range at 15 degrees elevation 

Range at 20 degrees elevation 


yards., 
.do 


6,430 
7 S10 


7,400 
8,900 


11,300 
13,100 


Range at 25 degrees elevation 


...do... 


8,920 


10,500 


14,600 


Range at 30 degrees elevation . . 


.do .. 


9,800 


11,540 


15,960 


Range at 45 degrees elevation 


do 


10 710 


12 300 






do 


10 760 


12 360 


17,5CO 













The Mark VI howitzer has a muzzle velocity of 1,300 feet per 
second and a maximum range of 10,760 yards and is of British design 
and of both British and American manufacture. The Mark VII 
howitzer has a muzzle velocity of 1,525 feet per second and maximum 
range of 12,280 yards and is of British design and manufacture. 
The Mark VIII| is an American modification of the British wire- 
wound Mark VIII howitzer to permit of a built up type of construc- 
tion and is strictly of American manufacture. The Mark VIIIJ has 
the same muzzle velocity and range as the Mark VIII. 

Due to the combination of British and American manufacture, 
there are several types of breech mechanism in service; the two 
main types are the T and the French percussion type. 

The three types of carriages differ but slightly in design. Each is a 
two-wheeled vehicle with a box-shaped trail, the latter being cut 
away to provide clearance for the recoil of the howitzer or gun when 
fired at high angles of elevation. The trails of the Mark VII and 
VIII-A types are modified to provide a larger clearance to accommo- 
date the Mark VIII^ howitzer and Mark XIX gun (see p. 246) and 
are also strengthened to withstand the greater energy of recoil. 

The howitzer is mounted in a cradle in which it is free to recoil 
under the control of a hydraulic recoil cylinder. After recoil it is 
returned to firing position by means of a pneumatic recuperator. 
The carriage permits of firing at high angles of elevation, and as the 
elevation is increased the length of recoil is proportionally decreased 
by a cut-off gear fitted to the cradle and buffer in order that the 
howitzer will not strike the trail or ground when fired. The recoil 
mechanism is of the hydropneumatic type with a variable recoil 
mechanism which lessens the length of recoil the greater the elevation 
given the howitzer or gun. The liquid used in the mechanism is 
British buffer oil. 



264 

The elevating mechanism permits a movement of 50 maximum ele- 
vation for the Mark VI carriage, 45 for the Mark VII carriage, and 
88 for the Mark VIIIA carriage. 

The cradle pivots on its trunnions and rests in bearings provided 
in the top carriage, which in turn is pivoted at its front center to a 
transom on the trad in such a manner that it is free to rotate under 




REAR VIEW OF CARRIAGE, SHOWING MAXIMUM ELEVATION OF HOWITZER. 

control of the traversing gear, 4 to the right or 4 to the left of the 
center line of 'the trail, a total of 8 traverse for each of the three 
types. 

A quick-loading gear is fitted to the cradle for bringing the howitzer 
rapidly to the loading position (7 30' elevation) after firing, and vice 
versa. 

The trail is composed of two side members supported at the front 
end of the axle and terminating in a spade at the rear end. Screw 
brakes for use in firing or traveling are fitted to either side at the for- 
ward end of the trail. 

A traveling lock is provided on the trail to lock the trail and cradle 
together to prevent strains on the elevating and traversing mechan- 
isms when traveling. 



265 

The wheels are made entirely of steel and have wide 1 ires fitted wil li 
steel cleats to ensure good traction. 

The sighting gear is composed of a rocking bar sight with panoramic, 
sight and clinometer for the usual method of sighting and a dial sight 
for the quick laying of the piece. 




RIGHT SIDE VIEW OF CARRIAGE IN BATTERY. 

Comparative table of weights and dimensions of 8-inch howitzer carriages, Marks VI and 
VII, and 6 -inch gun carriage, Mark VI II- A. 





Mark VI. 


Mark VII. 


Mark VIII-A. 


Weight of carriage (only) 

Weight of carriage, limber, and howitzer or gun 
Weight behind team, heaviest load 


pounds.. 
do.... 
do 


12,548 
21,700 
29,540 
19, 100 
528 
54.0 

"76.6 
685 
1,008 
60 
69 
95.8 
!4 right 
4 left 
26 right 
26 left 
66 
12 
76 

256.5 
260 


12.320 
22,650 
30,490 
20.050 
532 
64.8 
1.700 
76.8 
749 
1,859 
60 
69 
95.8 
4 right 
4 left 
26 right 
26 left 
66 
12 
76 

276.5 

280 


12,548 
25,110 
32,950 
22,796 


Weight of howitzer or gun carriage in firing position 
Weight at end of trial 


do.... 
do 


Volume of liquid in recoil cylinder 
Volume of air in recuperator cylinders 
Volume of liquid in recuperator cylinders 
Initial pressure " poun< 


.'.pints. . 
cu. in.. 
pints.. 
Is per sq. in.. 


64.8 
1,693 
76.8 
740 
1;678 
60.5 


Maximum air pressure 


Height of bore above ground 


inches . . 




do 


Width of carriage over axle . 


do 


95.8 
4 right 
4 left 
26 right 
26 left 
66 
12 
76 

322.5 
325 


Angle of traverse 


degrees., 
do 


Diameter of wheels 


inches . . 


Width of tires carriage 


rin 


Width of track, center line to center line of wheels do 
Maximum length of carriage, firing position (howitzer or gun hori- 


Maximum length of carriage, traveling position (howitzer or gun 
horizontal) innhAs 







The carriage limber is made of steel and has wide steel-tired wheels. 
At the rear is* a limber hook which engages the lunette at the trail 
end of the carriage. A chest is mounted on the limber, providing 
seats for the personnel, and fittings on the interior for carrying tools. 

The limbers which were manufactured in England have wooden 
chests, while those manufactured in America have steel chests. A 
connecting pole provides for motor transportation when traveling, 
the units being arranged in the following order: Limber, gun or 
howitzer carriage, and platform wagon, which combination is drawn 
by a tractor. 



266 

These types of carriages are provided with a platform by means of 
which a traverse of 26 right and 26 left is obtainable. The plat- 
form is used whenever conditions and time permit emplacement. 
For transportation the platform is disassembled and placed- on a 
transport wagon, which consists of two wheels and an axle, to which 
the parts of the platform are securely clamped. 
Eight-inch howitzer materiel (British) consists of: 
Model of 1917 (Vickers Mark VI and Mark VII). 
Model of 1918 (Vickers Mark VII). 
Limber, model of 1917 (Vickers). 
Firing platform and wagon, model of 1917 (Vickers). 
The 8-inch howitzer materiel, model of 1917 (Vickers Mark VI) , 
consists of: 

Carriage, model of 1917 (Vickers Mark VI). 
Howitzer, model of 1917 (Vickers Mark VI). 
Limber, model of 1917 (Vickers). 
Firing platform and wagon, model of 1917 (Vickers). 
The 8-inch howitzer materiel, model of 1918 (Vickers Mark VII) , 
consists of: 

Carriage, model of 1918 (Vickers Mark VII). 

Howitzer, model of 1918 (modified from Vickers Mark VIII to 

United States Mark VIIIJ). 
Limber, model of 1917 (Vickers). 
Firing platform and wagon, model of 1917 (Vickers). 
The above materiel is of British design and of both British and 
American manufacture. 



267 




* s 
B 

I s 



8-INCH HOWITZER AND CARRIAGE (BRITISH). 



The Marie VI howitzer is of the built-up-construction type and 
consists of a tube over which is shrunk a jacket. Front and rear 
guide rings provide means of supporting the howitzer in the cradle. 
A breech ring is also shrunk on for additional strength and carries a 
lug for connecting the gun to the recoil mechanism, and a breech 
bushing is provided for reception of the breechblock. The total 
length of this howitzer is about 10 J feet and its maximum range is 
approximately 10.760 yards; this howitzer is mounted on the Mark 
VI carriage. 




REAR RIGHT SIDE OF CARRIAGE IN FIRING POSITION. 



The Mark VI 11$ howitzer is also of the built-up-construction typo, 
but differs from the Mark VI howitzer in that it consists of two tubes, 
an inner and an outer, over which is shrunk the jacket. The jacket 
in this case supports the howitzer without the use of guide rings. A 
breech ring is shrunk on over the jacket and carries a lug for connect- 
ing the gun to the recoil mechanism. A breech bushing similar to 
that of the Mark VI is fitted for the breech mechanism. The total 
length of this howitzer is about 12 i feet and its maximum range is 
approximately 12,360 yards. This howitzer is mounted on the Mark 

VII carriage. 

(268) 



269 




270 




271 

The breechblock is of the interrupted-screw type. It is operated 
by a lever on the right-hand side of the breech, which by one motion 
releases the screw threads and opens the breech, or vica versa, on 
closing. 

The forward mushroom-shaped head of the breechblock is equipped 
with a flexible asbestos ring, known as the obturator pad. On firing, 
this ring is compressed and acts as a gas check to prevent the leakage 
of powder gases back through the breech. It has sufficient resili- 
ency to resume its original form after firing, as described on page 216. 

For firing the charge, two separate types of igniters or primers are 
used. The one known as the T tube consists of a. small T-shaped 
copper tube which fits into a suitable socket in the breech; it is fired 
by pulling a friction wire out of the tube by means of a lanyard. The 




BREECH BLOCK. 

other type, the percussion primer, is very similar in construction to a 
blank rifle cartridge. It fits a percussion firing mechanism on the 
breech which fires the primer by means of a hammer operated by the 
lanyard. This mechanism is common and interchangeable with the 
155 millimeter gun and howitzer; also the 240 millimeter howitzer. 

Howitzers fitted for one type of primer will not permit the use of 
the other type. Both types have a safety lock, which prevents 
firing when the breech is not entirely closed. 

The recoil mechanism is of the hydropneumatic long-recoil type and 
contains both recoil brake and recuperator. 

The recoil mechanism is an hydraulic brake to absorb the energy of 
recoil of the piece. It consists of a piston rod and piston traveling 
in an oil-filled cylinder. The piston rod is connected to the cradle 
18322820 18 



272 




273 

which remains stationary while the howitzer recoils. 'Die cylinder 
block is connected to a lug on the howitzer and recoils with it so that 
when the gun is fired the piston is forced against the oil in the cylinder. 
Ports are provided in the piston to permit of the passage of some of 
the oil. At the beginning of the recoil a large quantity of oil is per- 
mitted to pass, but as the howitzer further recoils a valve on the piston 
rod, operated by lugs sliding in spiral grooves in the cylinder walls, 
gradually closes the port so that no oil can pass and the howitzer is 
brought gradually to rest. 




FRONT VIEW OF HOWITZER CARRIAGE. 

In order to prevent the gun striking the ground when firing at 
high elevation, a method is provided for automatically closing the 
piston valves sooner as the elevation increases, thus shortening the 
recoil. The mechanism which accomplished this feature is known 
as the valve turning gear. 

The rear end of the piston rod is extended and so designed that it 
forms a counterrecoil buff er when it enters a suitable chamber bored 
out in the buffer plug. This buffer prevents violent return into 
firing position after recoil. 

The recuperator or counterrecoil mechanism serves to return the 
howitzer to firing position after recoil. It consists of two liquid cyl- 



274 

inders which are connected in turn with two air cylinders. On recoil- 
ing, the recuperator pistons force the oil out of the recuperator cylin- 
ders into the air cylinders, thereby highly compressing the air. When 
this air expands to its original volume it drives the oil back against 
the recuperator pistons, thereby returning the howitzer to firing 
position. The recuperator also acts as an auxiliary recoil buffer, 
absorbing up about 10 per cent of the energy of recoil. The air in 
the recuperator is maintained at a pressure of about 700 pounds per 
square inch in order to prevent the howitzer slipping back on the 
cradle at high elevations. A suitable pump is provided with the mate- 
rial for maintaining this air pressure. 




ELEVATING AND TRAVERSING MECHANISM. 

The carriage consists of a top carriage, cradle, trail, wheels with 
axles, and the elevating and traversing gear. The Mark VI and 
Mark VII carriage are similar in design and differ only in that Mark 
VII has a slightly larger recoil mechanism and the trail is cut out 
somewhat to allow for the greater length of the howitzer recoil. 

The top carriage is built up of nickel-steel plate and carries the 
trunnion bearings for the cradle. It is pivoted in the front transom 
of the trail, so as to permit the necessary traverse. 

The cradle which carries the recoil mechanism and provides slide 
ways for the recoil of the howitzer when in action, is supported by 
the trunnion bearings of the top carriage. 



275 




276 




277 

The trail is of the solid type, cut out to provide clearance for the 
howitzer to recoil. The spade is removable and the shoe or bracket 
may be substituted when firing on scotches or using the firing plat- 
form. 

The elevating and traversing gears are operated by handwheels on 
the left side of the carriage. The Mark VI carriage permits of an 
elevation of 50; the Mark VII, 45; and the Mark VIII-A, 38. 
Both carriages permit a traverse of 8. 

A quick-loading gear is provided to allow the gun to be brought 
rapidly to loading position when firing at high angles of elevation. 

The wheels are ol the all steel wide- tire type, 66 inches in diameter 
with tires 12 inches wide. They are fitted with brakes which act 
independently on each wheel. 

Sighting is accomplished by means of a rocking-bar sight supple- 
mented by a panoramic sight. These are located on the left SKU *.> 
the piece and serve to lay for elevation and traverse respective^. 
A dial sight is provided on the right side of the piece for quick laying. 

Ammunition of the separate loading type is used with the 8-inch 
howitzer. Shell issued is of the high-explosive type only and weighs 
200 pounds. These are issued filled but not fuzed and are fitted with 
a booster and adapter. Fuzes of types to suit different conditions 
of firing are provided, giving delayed or instantaneous action. 

The propelling charge is contained in cloth bags and is made up of 
separable increments, permitting various zones of fire. The maxi- 
mum charge for the Mark VI howitzer weighs 10.8 pounds; for the 
Mark Vlllf howitzer, 17.5 pounds. 

Separate loading ammunition is used in the 6-inch gun mounted 
on a Mark VIII-A carriage. The original British ammunition so 
closely resembled the American that it was decided to use the regular 
Mark II high-explosive shell. Each round is issued with the projec- 
tile filled, also the adapter and booster in place. The fuze hole in 
the adapter is fitted with a white metal plug. The weight of the 
projectile complete is 90.33 pounds. The propellant charge will 
consist of a base section and increment section having a total weight 
of approximately 25 pounds. 



8-INCH HOWITZER CARRIAGE LIMBER, MODEL OF 

1917 (VICKERS). 



The limber provided with this and for the 6-inch gun materiel is of 
steel construction and provides a chest for tools and spares, also seats 
for the personnel. No ammunition is carried in this limber, but two 
types of poles are provided, a long one for horse-drawn vehicles and 
a shorter connecting pole for motor traction. 

The box or chest of limbers manufactured in England is of wood 
and is bolted to the top of the rails. The lid is covered with water- 
proofed canvas and hinged at the front. Those limbers which were 
manufactured in the United States are provided with steel chests 
which vary slightly from the wooden chests in fittings provided for 
tools and accessories. 

The axle is cylindrical in shape and fitted with special axle arms. 
It passes through bearings formed in the rails and is held in position 
by brackets. 

The top of the chest is equipped with guard irons and blanket 
straps, receptacles being provided on the sides and ends to take an 
ax, a shovel, and other implements. The interior of the chest is fitted 
to carry tools, spare packings for buffer and recuperator, and other 
necessary stores. Clips are secured at the front of the chest to 
accommodate two rifles, used in emergencies when attacked en route. 

The wheels are 66 inches in diameter and have a tire 6 inches in 
width with rounded edges. 

Weights and dimensions. 

Length of wheel base, limber, and carriage (limbered) inches. . 187 

Overall length of limber, carriage, and firing platform wagon (tractor 

draft) inches. . 550 

Turning angle degrees . . 40 

Weight of limber, empty pounds . . 2, 160 

Weight of limber, fully equipped and loaded do 2, 600 

Diameter of wheels inches.. 66 

Width of tires do 6 

Width of track do. ... 82 

Weight of each wheel pounds. . 554 

Number of men carried 3 

(278) 



279 




280 




8-INCH HOWITZER FIRING PLATFORM AND WAGON, 
MODEL OF 1917 (VICKERS). 



A wooden firing platform is provided on which the carriage of the 
8-inch howitzer and 6-inch gun materiel can be mounted when suf- 
ficient time is permitted for setting up. The platform consists of 
wooden beams which assemble to form a triangular platform. The 
spade must be removed and a special bracket fitted on the trail 
when using this platform. This bracket travels in a groove which 
gives a bearing for the bracket and also provides a means of travers- 
ing the piece 52 on the platform. The platform is disassembled 
and mounted on a pair of wheels and axle for transportation. 

The main objects in the use of the firing platform are: To provide 
a reliable suppport for the wheels and rear end of the trail, so as to 
prevent sinking or movement when firing on soft ground; to insure 
the gun remaining on the target when firing; and to provide means 
for shifting the trail transversely through an angle of 52 (26 each 
side of center). By using the traversing gear on the carriage a total 
traverse of 30 on each side of the center is obtainable. 

The firing platform is composed of a support upon which the wheels 
of the carriage rest, two side beams hinged together at the forward 
end and a rear beam made in a top and bottom section. These com- 
ponents form a triangular-shaped frame upon which the carriage 
may be placed when firing. 

The support for the carriage wheels is placed near the apex of the 
triangle formed by the hinged side and rear beams. The rear beams 
form the base, the upper one being curved at its front edge to form 
a guide for shifting the trail. The carriage wheels rest on steel plates 
on the wheel platform and are guided by curved-steel angles which 
prevent lateral movement of the gun off the target when in -action. 

When the firing platform is used, the float plate, with spade 
attached, which is bolted to the underside of the trail, is removed and 
another float plate, having a thrust bracket attached, is bolted in 
its place. 

In traveling the units of the 8-inch materiel are arranged in the 
following order: Limber, carriage, and platform wagon. The usual 
plan is to draw this combination by a tractor. 

(281) 



282 

Weights and dimensions. 

Overall length of wagon (traveling position) inches. . 240 

Overall height of wagon do 66 

Overall width of wagon do 105 

Diameter of wheels do 66 

Width of tires do .... 6 

Width of track do 85 

Road clearance do 18 

Weight of platform pounds. . 5, 740 

Weight of wood platform and wagon (complete) do .... 7, 840 

Weight of steel platform and wagon (complete) do 9, 630 



9.2-INCH HOWITZER MATERIEL (VICKERS). 



The 9.2-inch and 240-milliineter howitzers are the largest weapons 
of the mobile type in service by the American Army at the present 
time. While these calibers are mobile in a sense, yet there are limits 
to their mobility, for when these howitzers have to be transported 
over land full of huge craters, with the roads entirely destroyed, the 
country encumbered with all kinds of de*bris, and frequently reduced 
to a sea of mud, one can realize just why a successful attack usually 
nets captured artillery, and on the other hand, if the trenches give 
way, it is rather difficult to got these heavy howitzers away quickly 
enough to save them from being captured by the enemy. 

Both types of 9. 2-inch howitzers are practically similar in all 
features, both being platform mounts as illustrated. These units 
break up into three separate loads for traveling, the howitzer proper 
forming one load, the top carriage and cradle the second load, and 
the platform the third load. 

The Mark I type of howitzer is 13 calibers long, while the Mark II 
type is 17.3 calibers, the principal difference being that the latter 
model is a more powerful weapon. Both types are provided with 
an earth box which is secured on firing beams, and in which the earth 
excavated for the firing beams is thrown; the additional weight gives 
greater stability when firing. 

The recoil mechanism is of the variable type which limits the 
amount of recoil according to the elevation, the recoil cylinder being 
fitted with a counterrecoil buffer to control the return of the howitzer 
into battery. A gravity tank insures that the recoil cylinder will 
at all times be filled with oil, but will provide the proper amount of 
void for expansion of the oil in the cylinder. 

The counterrecoil mechanism is of the pneumatic type consisting 
of a cylinder, a piston with rod, and a floating piston. The floating 
piston separates the oil and air chamber and the rod extending through 
the oil chamber provides a differential pressure and effects a seal, pre- 
venting the air leaking into the oil chamber. 

The operation of the howitzer in firing is that the recoil cylinder 
and the counterrecoil, or recuperator piston rod, move to the rear 
with the howitzer, the recoil piston rod and the recuperator cylinder 
remaining stationary. The flow of oil in the recoil cylinder past 
the piston rod and valve limits the length of the recoil and the com- 
pression of the air in the recuperator cylinder is sufficient to return 

(283) 



284 




285 

it to battery after the force of the recoil has been absorbed. The 
counterrecoil buffer in the recoil cylinder limits the counterrecoil of 
t he howitzer and allows the piece to return to battery position with- 
out shock. 

The howitzer, being comparatively thickset and short when com- 
pared with a gun of the same caliber, is capable of greater angle of 




FRONT VIEW SHOWING MAXIMUM ELEVATION OF HOWITZER. 

elevation than the same caliber of gun. The gun is primarily in- 
tended for attacking troops while the chief aim of the howitzer is to 
destroy incumbrance such as trenches, barbed wire, pill boxes, and 
the like. A shell that travels from the howitzer ascends at a high 
angle and drops' almost vertically. The explosion of a shell so fired 
is much more effective than one that is fired with only a slight ele- 
vated trajectory as in the case of the field gun of the same caliber. 



286 

From information based on actual experience, the 9.2-inch how-, 
itzer, Mark I type (low velocity), has an average life of 8,300 rounds, 
while the Mark IT (high velocity) has an average life of 3,500 rounds. 

The howitzer transport wagon is a four-wheeled vehicle the body 
of which contains a winch for removing and mounting the howitzer 
in the cradle. This vehicle is equipped for motor traction and has 
brakes acting individually on each hind wheel. 

The carriage bed (or platform) transport wagon is formed by fixing 
a front and rear axle to suitable attachments on the bed, thus forming 
the body of the wagon. Attachments are provided for brakes which 
act independently on each hind wheel and connections for attach- 
ment behind the howitzer transport wagon. 




LOADING POSITION OF HOWITZER, SHOWING SHELL ON TRAY. 

The top carriage transport wagon is formed by attaching two axles 
with wheels to the top carriage, which forms the body. Individual 
brakes are fitted on the hind wheels. This vehicle is usually coupled 
behind the platform wagon. 

The three wagons are drawn en train by tractor but may be hauled 
singly in case of necessity. 

The 9.2-inch howitzer materiel (Vickers), Mark I, consists of: 
Howitzer carriage, model of 1917. 
Howitzer platform transport wagon, model of 1917. 
Howitzer carriage transport wagon, model of 1917. 
Howitzer transport wagon, model of 1917- 
The 9.2-inch howitzer materiel (Vickers), Mark II, consists of: 
Howitzer carriage, model of 1918. 
Howitzer platform transport wagon, model of 1918. 
Howitzer carriage transport wagon, model of 1918. 
Howit/er transport wagon, model of 1918. 



287 




1S3228 20 19 



9.2-INCH HOWITZERS AND CARRIAGES, MARKS I AND 

II (BRITISH). 



This materiel is designed to be transported in separate loads, 
thus three four-wheeled vehicles are issued for this purpose. The 
first carries the howitzer, the second the carriage, and the third the 
platform and earth box, all of which is of British design, but the 
United States is in possession of equipment made both in this country 
and Great Britain. 




REAR VIEW OF CARRIAGE, SHOWING HOWITZER AT MAXIMUM ELEVATION. 

The howitzer consists of a tube, muzzle stop ring, a series of layers 
of steel wire, jacket, breech bushing, and breech ring. Over the 
exterior of the tube is wound a series of layers of steel wire extending 
from the breech end to the stop ring, which is shrunk over the tube 
at the' muzzle. Over the exterior of the tube is shrunk the jacket, 
which is secured longitudinally by the breech bushing. The bushing 
is prepared for the reception of the breechblock. The breech ring is 
screwed and shrunk over the jacket at the rear. 

(288) 



The Mark II differs in that it has two tubes shrunk one over the 
other, on which (he wire is wound. The Mark 1 howitzer is 133 
inches in length, while the Mark II is 17() inches. 

The breech mechanism of the screw type with plastic obturator is so 
arranged that by partially revolving the operating lever the breech- 
block is unlocked and the block with the gas-check pads and disks 
withdrawn from the seating in the chamber. The breech mechanism 
can then be swung into the loading position by means of a handle on 
the rear face of the breechblock. The breech is closed by a parallel 
screw having five portions of the screw thread removed longitudi- 
nally, each one-tenth of the circumference. The main characteris- 
tics of the Vickers 9. 2-inch howitzers are indicated in the accompany- 
ing table, giving the important dimensions, weights, and ballistics. 

The Mark I breech requires two operations to open. A handle 
turning on the rear of the block revolves and releases the block, then 




BREECH MECHANISM (MARK I). 

it must be swung open by the handle provided on the breech. The 
Mark II breech can be opened by one motion of a lever on the right 
side of the breech, which revolves and withdraws the breech in one 
motion from front to back. 

Both types are fitted with a firing mechanism to accommodate the 
T-tube primer. Later models are fitted with the French percussion 
type of firing mechanism described with the 155-millimeter howitzer 
materiel 011 page 216. 

The recoil mechanism is of the hydropiieumatic type and is equipped 
with a variable recoil, which shortens the length of recoil after 15 
elevation. 

The recoil cylinder is located above the howitzer, the former being- 
secured to the howitzer and moves with it, while the piston rod is 
secured to the cradle. The recoil is controlled by passage of oil 
through ports in the cylinder, which are varied by the valve located 



290 

near the piston on the rod. This valve is rotated by lugs which en- 
gage spiral grooves in the cylinder. A mixture of glycerine and oil 
is used in the cylinder. Later models are fitted with gravity tank 
on top of the recoil cylinder to replenish the oil and relieve pressure 
due to expansion. The end of the piston rod is extended and shaped 
to form a counterrecoil buffer. 

The recuperator is located below the howitzer; the cylinder being 
secured to the cradle remains stationary when the howitzer is recoil- 
ing; but the ram is secured to the howitzer and moves with it. The 
oil and air in this cylinder are separated by a floating piston. The 
ram on recoiling increases the liquid pressure on thi& piston ; this in 
turn compresses the air, which on expansion will return the howitzer 
to battery. An initial pressure of 475 pounds per square inch is 
maintained in the air chamjber to hold the piece in battery. 




RETAINING CHTCH 

BREECH MECHANISM (MARK II). 

To maintain this pressure a pump is attached to the carriage, which 
can be operated either by hand or a small gasoline engine. 

The cradle is a cylindrical chamber formed to house the howitzer. 
It is provided with trunnions and has the elevating arc secured to its 
lower side. Grooves cut in the cradle cylinder serve to guide the 
howitzer during recoil. A toothed arc on the left trunnion operates 
the valve turning gear through gearing. 

The top carriage or body is built up of steel plates. A front tran- 
som carries the pivot block, which fits over the pintle on the bed and 
on which the top carriage pivots. To the rear transom is secured a 
pinion which, meshes with a rack on the bed, serves to traverse the 
piece. Suitable platforms are hinged to the body, thus permitting 
access to working parts and loading platform on the rear for the per- 
*sonnel. On the left rear side of the body is a loading gear, which 
consists of a swinging arm with a winch and loading tray. 



291 




292 

The traversing gear is actuated by a liandwheel on the left side of 
the carriage, motion being transmitted to a vertical rack pinion which 
works in the rack at the rear of the bed : thus a traverse of 30 right 
and left may be obtained. 




METHOD OF LOADING, SHOWING LOADING GEAR MECHANISM IN ACTION. 

The elevating gear is operated by a handwheel on the left side of 
the carriage, which, through a system of gearing, operates the arc 
beneath the cradle. 




RIGHT SIDE VIEW OF CARRIAGE IN BATTERY. 

A quick-loading gear operated by a handwheel on the right of the 
carriage permits the howitzer to be brought readily to the loading 
angle, 3 depression. The firing angle ranges from 15 elevation to 
55 elevation. 



293 




294 




295 



The bed on which the top carriage pivots consists of two steel 
side guides of box section with transom, a pivot block, and a trav- 
ersing rack. The bearing of the top carriage is formed by an upper 
and lower roller path. At the front of the bed are suitable connec- 
tions for fastening a steel box which is filled with earth to help main- 
tain stability. 

Sighting is accomplished by means of a rocking-bar sight, a pano- 
ramic sight, or a No. 7 dial sight located on the left of the carriage. 

The rocking-bar sight serves to lay for elevation and carries the 
telescope sight or the dial sight for laying for direction. The dial 
sight is similar to the United States panoramic sight, which can be 
substituted. 

Ammunition employed is of the separate-loading type. High- 
explosive steel shell weighing 290 pounds are used, which are fitted 
with percussion fuses. 

The propelling charge is put up in cloth bags, charges being built 
up with four and with five increments for zone fire are provided. 
The charge is ignited by the T-tube friction type of primer. 

Weights, dimensions, and ballistics. 



Mark I. 



Mark II. 



Weight of howitzer without breech mechanism pounds.. 

Wei- lit of howit er with bree> h me< hanism do 

Total length of howitzer inuhes. . 

Rifling (uniform). 

Powder i haree pounds. . 

Weight of shell do.... 

Muzzle velo"ity ft. per sen. . 

Maximum ranre yards. . 

Wei< ht of mount in firing position complete with howitzer (but without dirt in 

earth box) pounds. . 

Weii h t of body and Cradle do 

Weirht of bed and earth box do 

Wei'ht of earth box empty do 

Woii ht of firin<r beams do 

Wei' ht of eround ramps do 

Length of recoil at 15 elevation inches. . 

Leneth of re'-oil at 50 elevation do 

Maximum angle of elevation degrees . . 

Loading anele (depression) do 

Amount of traverse. . . . . .do. . . 



2SO 

1,187 

10,060 

'29, 100 

10,100 

8, TOO 

1,600 

4,200 

410 

40 

19 

50 



9,576 
170J 

27 

290 

1,500 

13,080 

35,500 

11,200 

9,100 

2,100 

5,700 

530 

44 

19 

50 

3 



9.2-INCH HOWITZER TRANSPORT WAGON (VICKERS). 



This wagon consists of a front and rear axle and a steel rectangular- 
bed prepared for transporting the howitzer. 

The front axle is of forged steel, having an axle arm on each end, 
to which are fitted 60 by 6-inch steel tired wooden wheels. The 
steel framework is formed for the reception of the axle and draft 
pole, and has provisions for the attachment of a tractor. 

The bed for transporting the howitzer is prepared on its upper 
surface to receive the howitzer and is supported at the rear on an 
axle, each axle arm being provided with a dust excluder and linch 
pin. When traveling the front end of the howitzer is secured by 
pawls; the muzzle end being supported by two bronze brackets arid 




METHOD OF MOUNTING HOWITZER. 

secured by a wire rope and draw nuts. The frame is fitted with 
a draft link in rear for attachment of the draft connector of the next 
load. 

A winch gear for the purpose of shifting the howitzer into, or from, 
the cradle is provided consisting of an endless chain which, by means 
of sprocket wheels, imparts motion to a larger endless chain to which 
the howitzer is connected. 

Two rods, one on each side, are secured to a crossbar for connect- 
ing the rear of the wagon to the carriage body when mounting or 
dismounting the howitzer. 

The brake gear consists of two brake arms and brake screw fitted 
with handwheels and two brake blocks. Each side is operated inde- 
pendently by handwheels from the rear. A roller scotch and drag 
shoe, connected by chains, are attached for use when traveling. 

(296) 



297 




298 

Weights and dimensions. 







Mark I. 


O verall height 


inc-hes . . 


84 


Overall width 


do... 


96i 


Weight complete with load 


pounds 


10. 600 


Weight complete without Had 


do 


3 900 


Weight on front axle (loaded)... . 


do.... 


5,700 


Weight on- pear axle (loaded) 


v . do 


4.900 


Weight of each wheel 


do 


336 


Width of frfcek 


inches . . 


82 


Distance between axles. . . 


do 


88 


Turning aigle 


degrees 


36 


Turning circle diameter 


feet . . 


33 









Mark II. 



109 

14, 700 
5,200 
6,250 
8,450 



9.2-INCH HOWITZER CARRIAGE TRANSPORT WAGON (VICKERS). 

The carriage transport wagon consists of a front and rear axle, 
cross-bar, brake fittings, draft connection, and four wheels. 

The front axle is of forged steel equipped with arms on each end 
and to which are fitted the wheels. The raising screws for lifting the 
carriage into position, functions through two vertical holes in the axle. 

The draft frame is built up of steel plate and angles; is triangular 
in shape and formed to take a draft pole fitted with draft hooks for 
singletrees also joints for a tractor draft connector. The draft pole 
is the same as that used with the howitzer transport wagon. 

The rear axle is of steel, having its arms cranked and fitted with 
dust excluders, linch pins, and adjusting collars which are secured in 
position when traveling by the blocks and pivot on the front of the 
carriage body. These fittings allow of an oscillation which com- 
pensates for any unevenness in ground. 

Biake levers for each of the brake shoes, on each side of the vehicle, 
may be applied independently. The mechanism consists of brake 
screws, handwheels, brake nuts, and bands for connection to the 
axle. 

The roller scotch and drag shoe furnished are the same as those 
used with howitzer transport wagon. 

Weights and dimensions. 







Mark I. 


Mark II. 


Overall height 


inches 


103 


Ill 


Overall width '. . 


. .do . 


%| 


109 


Weight complete with load 
Weight complete without load 


pounds.. 
... . . .do . . 


12,600 
2,600 


14,800 
3,600 


Weight on front axle (loaded) 


do 


5 000 


5,500 


Weight on rear axle (loaded) 


do 


7 600 


9 300 


Weight of each wheel. 


do 


336 


336 


Width of track . 


inches 


82 


86 


Distance between axles . . 


do 


115 


129 


Turning angle 


degrees 


32 


f30 right. 


Turning circle, diameter. 


feet 


34 


\36 left. 
25 











299 



9.2-INCH HOWITZER PLATFORM TRANSPORT WAGON (VICKERS). 

The howitzer platform-transport wagon in general is very similar 
to the howitzer carriage-transport wagon. The front axle and draft 
connections are entirely similar to those on the howitzer carriage- 
transport wagon, except that only one hole in the center of the axle 
is provided for the raising screw. When preparing for travel the 
rear axle, which is fitted with two vertical holes for lifting screws, is 
attached to rear of the bed. The axle is fitted with dust exchider, 
linch pins and adjusting collars, and a brake gear which is operated 
from the rear by handwheels, each side being operated independently. 
The roller scotch and drag shoe are similar to those used wath* the 
howitzer carriage- transport wagon. 

Weights and dimensions. 







Mark I. 


Mark II. 


Overall height 


.inches . 


65ft 


60 


Overall width 


do 


964 


109 


Weight complete with load 


pounds.. 


10,000 


12,500 


Weight complete without load. 


do 


2 700 


3 500 


Weight on front axle (loaded) 


do 


4 900 


5 700 


Weight on rear axle (loaded) 


do 


6 000 


6*800 


Weight of each wheel 


do.... 


336 


336 


Width of track . 


inches 


82 


86 




do 


160 


174 


Turning angle.... 


degrees 


40 


f36 right. 


Turning circle, diameter 


feet 


48 


\40 left. 
43 











240-MILLIMETER HOWITZER MATERIEL, MODEL OF 
1918 (SCHNEIDER). 



The 240-millimeter howitzer unit, a French design translated to 
accommodate American manufacturing practice, differs from the 
smaller type of field artillery pieces in that it is split up into a number 
of loads for transport. When arranged for firing the carriage is set 
upon a structural-steel platform which rests in a special prepared pit 
and has a large trunk portion embedded in the ground to absorb the 
reaction of the recoiling parts. The platform is stabilized by two 
hinged floats at the rear. 



FRONT VIEW OF CARRIAGE, SHOWING MAXIMUM ELEVATION OF HOWITZER. 

Although approximately the same size as the British 9.2-inch how- 
itzer (the exact diameter of the bore of the 240 being 9.45 inches) and 
only a little larger than the 8-inch howitzer, the French gun is by far 
more powerful than either. The 8-inch and 9.2-inch howitzers have 
ranges in the neighborhood of 6 miles, their shell weighing 200 and 290 
pounds, respectively. On the other hand, the 240 hurls a shell weigh- 
ing 356 pounds and carrying a bursting charge of 45 to 50 pounds of 
high explosive, obtaining a range of almost 10 miles. It is-estimated 
that the life of the 240-millimeter howitzer before relining is approx- 
imately 5,000 rounds. 

(300) 



301 




302 




303 



Comparative characteristics of heavy artillery. 





8-inch howitzer carriage. 


9.2-inch howitzer carriage. 


240-millime- 
ter howitzer 
carriage. 


Mark VI. 


Mark VII. 


Mark I. j Mark II. 


Weight of projectile pounds 


200 
1,300 
10,760 

29,540 

19,100 
Hydropneu- 
matic. 
50-24 
0-50 
152 


200 
1,522 
12,360 

30,490 
1 

20,048 
Hydropneu- 
matic. 
52-24 
0-45 
152 


290 
1,187 
10,060 

10,640 
3 

16,240 
Hydropneu- 

40-25 
15-50 
60 


290 
1,500 
13,080 

14,410 

19,040 
Hydropneu- 
matic. 
44-19 
15-50 
60 


356 
1,790 
17,009 

14,000 
4 

37,920 
Hydropneu- 
matic. 
46.7 
-1-60 
20 


Muzzle velocity, feet per second 
Maximum range, yards 


Weight behind tractor heaviest load, 




Weight of carriage and gun in firing 




Length of recoil inches . . 




Total traverse degrees 





* Traverse when firing platform is used; without platform a traverse of 8 is obtainable. 

In firing position the howitzer proper interlocks and becomes inte- 
gral with the sleigh containing the recoil mechanism. A liquid con- 
sisting of glycerine and water boiled for 15 minutes is used in the 
recoil cylinders and a mixture of glycerine, water, and caustic soda 
is used in the recuperator. 

The sleigh has two bronze-lined slideways which engage the clips 
on the cradle so that the sleigh slides upon the cradle when the how- 
itzer recoils. At the front of the cradle there is attached a cast-steel 
beam to which the piston rods of the recoil and recuperator cylinders 
are bolted. The cradle also carries the elevating segments, the firing 
mechanism, the quick-return mechanism, and a trunnion band which 
supports the cradle in the trunnion bearings of the top carriage. 

The top carriage is composed of two steel flasks united by cross 
transoms and end plates, and at the rear end carries the brackets 
which support the loading platform and crane. The top carriage is 
pivoted at the front on a pintle seat supported by a set of Belleville 
springs in a pintle socket on the platform. This facilitates traversing 
the top carriage to its limits of 10 degrees either to the right or left. 

The howitzer is served by a shot truck which carries two 356- 
pound projectiles and runs on an industrial track to and from the 
ammunition dump. The projectiles are lifted from the shot truck 
and placed on a rammer car by shot tongs and cable operated by a 
hand crane, all of which is supported by a loading platform at the 
rear of the top carriage. The rammer car, operated by hand cranks, 
moves along a track into the cradle, registering and locking with 
the breech of the howitzer, after which the projectile is pushed into 
position by a semiflexible chain, the powder charge being pushed in 
by hand. 

For transportation the complete howitzer unit is divided into four 
loads, namely, howitzer, cradle, top carriage, and platform. Each 

18322820 20 



304 

unit is composed of a limber, false trail, and a rear two-wheeled wagon. 
The tools and accessories for each unit are carried on two 4-ton trail- 
ers and the six loads are drawn by caterpillar tractors. 

In assembling and dismounting, an erecting device made of struc- 
tural steel is used for placing the platform and top carriage in posi- 
tion. The cradle and howitzer are drawn into place by a cable and 
windlass which is attached to the forward part of the top carriage. 
This erecting device is also used for lifting and placing projectiles 
on the shot truck from the shell storage. 

The howitzer, when elevated to about 43 J and using a propelling 
charge of 35 pounds, giving a pressure of about 33,000 pounds per 
square inch on the base of the projectile, will fire a projectile weigh- 
ing 356 pounds and containing a bursting charge of about 49 pounds 
of T. N. T. to a distance of approximately 10 miles. 




METHOD OF LOADING THE HOWITZER WITH RAMMER CAR. 

The following sighting equipment is carried with the 240-millimeter 
materiel : 

Quadrant sight, model of 1918. 

Panoramic sight, model of 1917. 

Peep sight. 

Sight extension. 

Gunner's quadrant, model of 1918. 

Night lighting equipment for sights. 

Ammunition of the separate loading type is used with this how- 
itzer, consisting of point-fuzed high-explosive common-steel shell 
and point-fuzed gas semisteel shell. The shells are issued filled but 
not fuzed, the fuze hole being closed with a suitable plug. The 
components of each round are the primer, the propelling charge, the 
filled projectile, and the fuzes. 

To transport the complete carriage, there are provided four trans- 
port vehicles howitzer trans'port wagon, top carriage transport 
wagon, platform transport wagon, and cradle transport wagon. 



305 




306 




307 

Each transport vehicle consists principally of a limber, faJse trail, 
and rear axle and wheels. 

The limber consists of wheels, axle, pole, and turning arc and is 
similar for each wagon. It is equipped with a pintle, over which 
fits the lunette ring of the false trail. The turning arc is attached 
to the axle, and the false trail bears on it as it rotates around the 
pintle. 

Four false trails are provided, one for -each wagon. They are 
fitted at the front end with a lunette ring and at the rear with a 
locking arrangement for attachment to the unit to be transported. 

The rear axles are provided with suitable means for attachment to 
their respective units, and band brakes are fitted on all the rear 
axles. 

When the complete carriage is set up for firing, the transport 
vehicles are close coupled by means of the false trail and form short 
units, having four wheels, which can be drawn away. All wheels 
are equipped with solid rubber tires. 
240-millimeter howitzer materiel, model of 1918 (Schneider}, consists of: 

Howitzer and carriage, model of 1918. 

Howitzer carriage limber, model of 1918. 

Howitzer transport wagon, model of 1918. 

Howitzer cradle transport wagon, model of 1918. 

Howitzer top carriage transport wagon, model of 1918. 

Howitzer platform transport wagon, model of 1918. 

The above materiel is of French design, but was manufactured 
only in the United States. 

240-MILLIMETER HOWITZER AND CARRIAGE, MODEL OF 1918 

(SCHNEIDER). 

The howitzer is built up of alloy steel and consists of a tube, a 
jacket, and hoop. The jacket is shrunk on the rear end of the tube 
and is secured from slippage by threads cut in its inner surface, 
which screw r over corresponding threads on the tube, the rear end 
of which is prepared for the reception of the breechblock. The 
hoop is shrunk and screwed on the tube forward of the jacket, which 
is fitted at its rear end with a hinge lug, vertical clips for joining the 
howitzer to the sleigh, and guide bosses for joining the sleigh to the 
howitzer; also a T slot to suit the false trail when entrain. At the 
front end of the hoop is a boss to accommodate the axles of the 
transport wagon and lugs for rollers used in the dismounting and 
mounting of the howitzer. 

The breech mechanism is of the interrupted-screw type and is 
fitted with a plastic obturator. One motion of the breech lever 
swinging from left to right turns and swings the breech clear. 



308 

The firing mechanism is of the French percussion type, the same 
as used on the 155-millimeter howitzer, and is interchangeable with 
the mechanism of the following materiel: 

155-millimeter gun, model of 1918 (Filloux). 
155-millimeter howitzer, model of 1918 (Schneider). 
8-inch howitzer, Marks VI and VIII (Vickers). 

The sleigh, a steel forging, is bored out to house the recoil mechan- 
ism and supports the howitzer, being attached to it by lugs and 
locking clips, and therefore recoils with the howitzer when in action. 
Grooves in the sleigh house guides fastened to the cradle which 
serve to guide the howitzer in recoil. The sleigh is also fitted with 
two tracks for the rollers on the howitzer, which are used in mounting 
and dismounting. 

The cradle carries the trunnions and is a nonrecoiling part. The 
recuperator piston rod and the recoil piston rods being attached 
to it. 




MOUNTING THE CRADLE. 

The recoil mechanism is of the hydropneumatic, long-recoil type, 
the length of recoil being constant for all elevations. In the sleigh 
forging are bored five longitudinal cylinders, the upper two being 
bored about half the length of the sleigh and are closed at the front 
end by caps, forming air reservoirs. The left reservoir has an open- 
ing in which the pressure gage is fitted to test the pressure of air or 
gas. 

The lower cylinders extend the full length of the sleigh, while the 
two outer cylinders form the recoil and the middle the recuperator 
cylinder. The recuperator cylinder is connected by passages to the 
two air chambers, permitting the liquid from the recuperator to flow 
into them. 

The recoil piston rods are hollow and are fixed rigidly to the 
cradle. In the hollow space travel the throttling rods, which move 
with the recoiling parts. These rods are so shaped that they give 
a throttling effect on the liquid which passes through annular open- 
ings around the piston. On return to battery the throttling rods 
act as a buffer to prevent violent return into batten-. 



309 




310 




311 

The air (or nitrogen gas) in the recuperator is maintained at a 
pressure of 568 pounds per square inch, which is sufficient to keep 
the howitzer in battery at all elevations. Tanks of compressed 
nitrogen are kept at hand to replenish that in the recuperator in 
case the pressure gets low. The liquid used in both recuperators 
and recoil cylinders is a mixture of glycerine and water. Suitable 
pumps are provided for filling these cylinders. 

A firing handle is fitted on the left side of the cradle, which, through 
a system of shafts, operates the percussion hammer on the breech 
the firing handle being accessible at all elevations of the howitzer. 
In case of emergency the piece may be fired by means of a lanyard. 

The elevating mechanism consists of elevating arcs, which tip the 
cradle, is operated by a handwheel on the left side of the carriage 




MOUNTING THE TOP CARRIAGE. 

through a system of gearing. A maximum elevation of 60 can be 
obtained. 

In connection with the elevating gear a quick-loading gear is 
provided, by means of which the howitzer can be quickly brought to 
the loading angle (9 15') and again elevated without the use of the 
slower method of using the elevating gear. A handwheel on the 
right side of the carriage is used to operate the quick loading gear. 

The top carriage is a structural steel, built-up unit. The top of the 
flasks forming the top carriage carry the trunnion bearings for the 
cradle. At the front of the carriage a pintle bearing is provided, 
which bears on the pintle of the platform, thus providing a means of 
rotating the top carriage and traversing the piece. A pinion at the 
roar of the carriage meshing with a rack on the platform swings the 



312 

rear end of the carriage in traverse. A traverse of 10 each side of 
center is thus obtained. 

A windlass mounted on the top carriage is used for setting up and 
dismounting the unit. 

At the rear of the top carriage is attached a loading platform on 
which is mounted a loading crane for handling the shells. On the 
loading platform tracks are provided for a rammer car which is used 
to transport a projectile from the loading crane to the breech and to 
ram it into the bore of the howitzer. This ramming of the projectile 
is accomplished by means of a movable; chain on the rammer car 
which has suitable lugs for engaging the shell and is operated by 
cranks on the rammer car. 

The platform on which the top carriage rests is a structural-steel 
unit composed of a top and bottom plate secured by channels. The 
middle portion is open and has a trunk section to provide a space 
for the howitzer to recoil at high angles of elevation. The traversing 




METHOD OF LOWERING PLATFORM. 

rack is secured to the rear end of the platform. Built-up steel floats 
are attached to the rear of the platform by swinging arms, which 
function to give stability to the mount at extreme angles of azimuth. 
Axle brackets and attachments for the false trail of the transport 
wagon are provided for use when traveling. 

Accessories. A considerable number of tools and accessories are 
required for the erection, operation, and maintenance of the piece. 
The principal ones are as follows: Erecting frame, shot truck, sights, 
transport wheel tracks, track for shot truck, shell tongs, shot barrow, 
air pump, liquid pump, hydraulic jacks, wheel blocks and mats, axle- 
lifting levers, etc. 

The erecting frame is composed of structural-steel beams. It is 
operated by hydraulic jacks and is used in assembling and dismount- 
ing the piece. It may also be used as a derrick for handling shells. 
When used for this purpose, a trolley attachment with shell tongs is 
provided. 



313 




314 




315 

The shot truck is a four-wheeled vehicle with flanged wheels fitting 

a track which is laid from the magazine to the piece, and will carry 
two of the projectiles. The track for this truck is 600 millimeters 
(23 1 inches) gauge. It is supplied in built-up lengths of light steel 
rails joined by pressed-steel ties. 

Weights, dimensions, and ballistics. 

Weight of howitzer pounds. . 10, 790 

Length of howitzer inches. . 399. 6 

Rifling Right hand, 1 turn in 40 calibers at origin to 1 turn in 20 cali- 
bers at a point 24.369 inches from the muzzle. 

Weight of powder charge pounds. . 38 

Weight of projectile do 356 

Muzzle velocity ft. per sec.. 1,700 

Maximum range yards. . 18, 000 

Weight of howitzer and breech mechanism pounds. . 10, 831 

Amount of traverse (right and left) degrees. . 10 

Maximum angle of elevation of howitzer do 60 

Maximum angle of depression of howitzer do 1 

Loading angle do 9 

Normal length of recoil inches. . 44. 83 

Maximum recoil allowable do 46. 73 

Height to center of trunnions do 64. 5 

Weight of howitzer and transport wagon pounds. . 15, 220 

Weight of cradle and transport wagon do 14, 605 

Weight of top carriage and transport wagon do 12, 545 

Weight of platform and transport wagon f do 16, 230 

Weight of complete unit in firing position do 41, 296 

Weight of erecting frame do 33, 024 

Sleigh (complete, filled with liquid and all pistons, packings, caps, etc.) -do 5, 747 

Cradle (complete, but without elevating arms) do 4,068 

Recuperator (steel forging only), completely machined do 3, 931 

Elevating arms (including quick-loading gear) do 855 

Top carriage (complete, with elevating and traversing gear, windlass, 
footboards, bearing caps, traversing rollers, rear clips, draft hook, cradle 

lock, jack rollers, etc pounds. . 6, 685 

Rammer car do 540 

Loading platform do 555 

Loading-crane bracket and loading crane do 441 

Shell tongs do 39 

Shot truck do 430 

Platform (complete, with pintle springs, swinging arms, and floats) do 11, 895 

Transport wheel tracks with inclined planes do 1, 175 

Erecting frame (complete, with hydraulic jacks) do. ... 3. 024 



316 




317 




240-MILLIMETER HOWITZER TRANSPORT LIMBERS 

AND WAGONS. 



In order to transport the complete carriage there are provided 
four transport vehicles, namely, the howitzer transport wagon, top 
carriage-transport wagon, platform-transport wagon, and cradle- 
transport wagon. Each wagon consists principally of a limber, false 
trail, rear axle, and wheels. 




HOWITZER TRANSPORT WAGON. 



The limber consists of two wheels, an axle, pole, and turning arc, all 
of which are similar for each wagon. 

The pole is composed of two steel parts joined with a flexible 
spring coupling, consisting of a coil spring, plunger, and hinged joint, 
providing a movement of about 15 inches at the end of the pole to 




CRADLE TRANSPORT WAGON. 

make up for any difference in height between the limber and the 
vehicle to which it may be coupled. This spring coupling also 
relieves the vehicles of any sudden shocks during transportation. 

Each limber is provided with a pintle over which fits the lunette 
ring of its false trail. Safety chains are attached to the pole to hold 
the false trail on the pintle in proper position. 

(318) 



319 



The turning arc is attached to the axle and the false trail bears on 
it as it rotates around the pintle. 

Four false trails are provided, one for each wagon. They are 
similar in most respects, especially the front end that has the lunette 
ring. This lunette ring floats in the trail and is surrounded by 
coiled springs which take up the shocks incidental to transportation. 




TOP CARRIAGE TRANSPORT WAGON. 

The body of the false trail is formed to suit the heights of the unit to 
which it attaches and has brace rods for stiffening. A locking 
arrangement is provided to lock the units to the false trails and is 
operated by means of a hand lever. 

The rear axle of the transport wagon is made of a special forging 
shaped to suit the unit which it carries. The axle for the howitzer- 



Ij^V <PMj 

^^mn r?1i 








PLATFORM TRANSPORT WAGON. 

transport wagon is curved to suit the radius of the howitzer and has 
pawls which lock the howitzer in place. 

Band brakes are used and are alike for all four types of rear axles, 
but the brake-operating mechanism is different for the various trans- 
port wagons. The brakes on each vehicle are connected by a con- 
necting lever shaft which is operated by a lever with ratchet and 
pawl. Provision is made for the setting of the brakes by the operator 
18322820 21 



320 

of the hauling tractor by means of a rope attached to the operating 
lever and extending to the tractor. 

When the complete carriage is set up for firing, the transport 

vehicles are close coupled by the false trail and form short units, 
having four wheels which can be drawn away. Brackets are provided 
attached to each axle for the brace rods which are used when the 
vehicles are unloaded and close coupled. 

Both the limber and rear axles are equipped with standard rubber- 
tired wheels. 

Weights and dimensions. 

Howitzer and transport wagon (complete) pounds. . 15, 200 

Weight of transport wagon (close coupled) do 4, 385 

Weight of front wheels and axle do 1, 185 

Weight of rear wheels, axle, and brake do 2, 750 

Weight under front wheels do 4, 864 

Weight under rear wheels do 10, 356 

Wheel base inches. . 162 

Overall length do. ... 314 

Cradle (with elevating arms and sleigh) transport wagon pounds. . 14, 605 

Weight of transport wagon (close coupled) do 4, 335 

Weight of front wheels and axle do 1, 185 

Weight of rear wheels, axle, and brake do 2, 700 

Weight under front wheels do 3, 530 

Weight under rear wheels do 11, 075 

Wheel base inches. . 150 

Overall length do. ... 267 

Top carriage (with rammer car, loading platform, loading crane) and trans- 
port wagon pounds. . 12, 545 

Weight of transport wagon (close coupled) do 4, 285 

Weight of false trail complete for platform do 475 

Weight of false trail for cradle, howitzer and top carriage, each do 450 

Weight of front wheels and axle do. . ., 1, 185 

Weight of rear wheels, axle, and brake do 2, 650 

Weight under front wheels do 4, 030 

Weight under rear wheels do 8, 515 

Wheel base . ? ..i inches. . 181 

Overall length do. ... 280 

Platform and transport wagon (including brake lever and draft hook). pounds 16, 230 

Weight of transport wagon (close coupled) do 4, 335 

Weight of front wheels and axle do 1, 185 

Weight of rear wheels, axle, and brake do 2, 675 

Weight under front wheels do 4, 485 

Weight under rear wheels do 11, 745 

Wheel base inches. . 153 

Overall length do 292 

Weight of limber wheel pounds. . 350 

Weight of transport wagon wheel do 1, 050 

Howitzer transport wagon (close coupled) do 4, 385 

Cradle transport wagon (close coupled) do 4, 335 

Top carriage transport wagon (close coupled) . do 4, 285 

Platform transport wagon (close coupled) do 4, 335 



321 

Maximum width of transport wagons (platform) inches. . 102 

Maximum height of transport wagons (top carriage) do 102 

Minimum road clearance (distance between lowest point of wagon and ground) 

inches . . 15 

Diameter of smallest circle in which a transport wagon will turn do 544 

Wheels on transport wagons, rubber tired do 60 by 8 

Wheels on limber, rubber tired do 49 by 4 

Limber wheels: 

Width of track, center to center of tire do 60. 83 

Bearing surface do 3. 54 

Rear wheels: 

Width of track, center to center of tire. . . do. . . . 63. 84 

Bearing surface do 4. 74 

Maximum width of widest transport wagon (platform) do 102 

Maximum height of highest transport wagon (top carriage) do 302 

Maximum overall length of longest transport wagon (howitzer) do 314 



ANTI-AIRCRAFT ARTILLERY. 



In considering the question of antiaircraft materiel it is to be re- 
membered that the science of anti-aircraft gunnery has changed prob- 
ably to a greater extent than that of any other branch of the service. 
It was unheard of at the beginning of the war, and in consequence 
has grown from nothing at all to an important phase of operations. 
As a result, materiel is constantly changing and can not be said to have 
reached a definite basis even at this time. The materiel was greatly 
affected also by the change from " position warfare" to warfare of 
motion; portability changing from a somewhat neglected factor to one 
of paramount importance. 

In field artillery practice range problems are presented in connection 
with mortars, howitzers, and guns, but the results to be accomplished 
and the problems in connection with each of these weapons are quite 
different. The provided elevation of the guns of some calibers is 
small, while the muzzle velocity of some of the howitzers and all of 
the mortars is comparatively low; also the traverse of all three differ- 
ent types of weapons is limited. The field target is usually stationary, 
maps being available for establishing its position, and ample time 
is available in which to figure its range. Observation of the point of 
fall of one shot serves as a guide in correcting the range for the next 
shot. Frequently it is possible to choose atmospheric conditions 
under which the weapon would be employed, and assisting or opposing 
longitudinal windage, or driftage due to side windage, is calculated 
with the aid of wind gauges. 

For anti-aircraft service the problem is entirely different. The 
single weapon must be able to cover the elevations of all three types 
of the field artillery weapons and preferably have a traverse of 360. 
These wide variations in elevation introduce serious recoil problems, 
andT the difference in the traverse problem may be to some extent 
illustrated by reference to the fact that the total traverse of the 75- 
millimeter French, model 1897 Ml, field gun is only 6. 

Instead of a stationary target there may be presented one whose 
speed is one-sixth of the speed of the projectile itself and whose course 
can in no wise be forecast by road direction or terrain formation and 
whose position may be at any vertical or horizontal angle. The pos- 
sible altitude and speed of airplanes increased from time to time, 
making useless the earlier and present basic data to be employed in 
the design of protective materiel. Under certain conditions of air- 
plane approach the range must be calculated on the instant and there 
is no choice as to atmospheric conditions. As the target is not sta- 
tionary, range corrections are difficult to estimate by observation. 

(322) 



323 

While gauges may indicate the direction and force of the wind at the 
altitude at which they are set, they furnish no indication of air cur- 
rents existing at other altitudes through which it might be necessary 
for the anti-aircraft projectile to pass. With the flat trajectory of a 
fieldpiece at but a few degrees elevation, the density of atmosphere 
through which the projectile must pass is largely uniform, while at 




high angles of fire with anti-aircraft guns the projectile 
through atmospheres of different rarefactions, and hence different re- 
sistances to the passage of the projectile. These influences affect the 
trajectory of the projectile, the rate of travel of the projectile, and the 
time element of the burning of the fuze. 

With field artillery, shrapnel is employed with both a time fuze and 
an impact fuze, and high-explosive shell with impact fuze only, but 



324 

anti-aircraft disrupting projectiles are fitted only with time fuzes, as 
otherwise a projectile which has missed its aerial mark would be apt 
to cause damage within friendly lines through impact explosion on 
reaching the ground. 

As there is practically no position which is entirely free from the 
possibility of aircraft attack, and as there is no means of determining 
the direction from which such attack may come, ready mobility of 
anti-aircraft guns is most desirable, and as opportunity to reach the 
target is frequently only momentary, rapidity of sighting and of firing 
is essential. In the case of indirect fire from a camouflaged position, 
the gunner has not even had a view of the approaching plane, but 
must lay his gun on the basis of telephone data, or data otherwise 
transmitted from the battery commander's station. 

The anti-aircraft target may be a balloon either stationary or 
towed a dirigible, or an airplane, but is most frequently the latter. 
Location of the position of balloons or dirigibles is comparatively 
simple, as compared with airplane location, owing to the size of the 
target and the stationary position or low speed of motion. For night 
fire, searchlights or other illuminating means are required, and for 
night fire or protective fire in thick weather, sound-locating devices 
are employed. 

The earlier fire from anti-aircraft artillery was directed solely from 
the burst; that is, by firing a shot, and judging of the direction of the 
next shot solely by observation of the nearness to which the burst of 
the first shot had approximated the position of the target. In the 
meantime, however, the position of the target had changed. This 
system has given way to the use of an elaborate system of instruments 
for the determination of fire in accordance with certain established 
principles. 

In the attack upon aircraft the desired end may be accomplished 
either by the destruction of the aircraft itself or by the disabling of its 
occupants, in which latter case the destruction of the aircraft would 
follow. The methods adopted include destruction by incendiarism, 
by direct hits, by flying particles from exploding shell or shrapnel, 
and by shell shock. Methods of fire may involve explosive projec- 
tiles from a single gun, salvos or barrage fire from a number of guns, 
rapid firing from pom-poms (small caliber guns, firing explosive pro- 
jectiles), or from machine guns firing small arm ammunition. 

Because of the important field played by aerial sound-detecting 
apparatus, searchlights, and telephony, including wireless, future 
progress in the design of anti-aircraft artillery will consider these 
subjects. With the perfection of airplane motors and their intercon- 
nected functioning apparatus, the design of aircraft, and the art of 
flying, other factors upon which the design of artillery equipment 
should likewise be based, enter into this problem. 



325 




3-INCH ANTI-AIRCRAFT GUN MATERIEL, MODEL 1918. 



It is hardly possible to estimate how great will be the future 
importance of the perfection of the country's aerial defense from a 
strategic point of view. Aviation as an offensive arm will remain a 
principal arm, and anti-aircraft artillery, as a defense branch, will play 
the part that coast artillery plays to the naval squadrons. 

Anti-aircraft gunnery differs from other forms of gunnery, such 
as field-artillery problems. It is a new subject, one more compli- 
cated than any other artillery problem, and consequently one which 
essentially demands new methods and modes of measurement. De- 
velopment, however, has led to the design of the 3-inch auto-trailer 
carriage. 

The 3-inch auto-trailer carriage unit consists of a 3-inch gun, 
model 1918, anti-aircraft, and a 3-inch auto-trailer carriage, model of 
1917, mounted on a four-wheel trailer truck, having springs and solid 
rubber tired wheels. The gun and the mount remain fixed on the 
trailer, both in traveling and in battery positions. 

The muzzle velocity of the gun is 2,400 foot-seconds. Both 
shrapnel and high-explosive shells, each weighing about 15 pounds, 
are employed. At a maximum elevation of 85 the maximum verti- 
cal ordinate, limited by the time fuze, is 7,940 meters. At minimum 
elevation of 10 the projectile strikes the ground at approximately 
6,100 meters. At 23 elevation the bursting vertical ordinate is 
1,176 meters, and the horizontal ordinate approximately 7,025 
meters. 

The recoil mechanism is similar to that employed with the Ameri- 
can 75 millimeter, model 1916, field gun, but with the use of a spear- 
head counter-recoil buffer. This recoil mechanism is of the hydro- 
spring type and the variable adjustment of the stroke is governed 
by a rotating valve, the movement of which moves port holes behind 
the edges of three lands permitting the passage of oil to the by- 
passing recesses. 

The anti-aircraft gun, together with the recoil mechanism, is held 
by the cradle and swings from 10 to 85 elevation in the trunnion 
bearings of the top carriages. A base plate rigidly bolted to the 
trailer chassis supports the top carriage on traversing rollers on which 
the top carriage rotates 360 in azimuth around a pintle on the base 
plate. 

The trailer carriage is equipped with outriggers. Stability and 
lifting jacks which, when in firing position, rest on detachable floats 

(326) 



327 




328 

on the ground and support the entire weight of carriage and trailer. 
These outriggers and jacks are employed to stabilize this unit when 
in action and to prevent the mount from overturning when the gun 
is fired at low angles of elevation. 




VIEW OF REAR OUTRIGGERS FOLDED; OUTSIDE END OF RIGHT OUTRIGGER 
BRACE READY TO BE PLACED IN RECEPTACLE; SCREW JACK WITH 
OUTRIGGERS FOLDED. 

In traveling position the outriggers are folded up, the jack screws 
raised, the floats and spades being carried in another vehicle, with 
the exception of the stability jack floats which are attached to the 
jack screws. Traveling locks are provided to lock the gun at about 



329 




331 

20 elevation to protect the elevating mechanism. In azimuth the 
carriage is locked lengthwise of the trailer to remove unnecessary 
strains from the traversing mechanism when the unit is traveling. 

Adjustable seats and foot rests for the gunners and platforms that 
fold up when traveling are fastened to the top carriage. This unit 
is considered able to negotiate any roads suitable for field artillery. 
Weight of complete unit is approximately 14,000 pounds. 

Fixed ammunition is used with these guns, consisting of time- 
fuzed high-explosive, illuminating shell, tracer shell, and shrapnel. 
All the shell and shrapnel are issued fuzed. 

3-INCH AUTO-TRAILER CARRIAGE. 

The 3-inch auto-trailer carriage consists of a 3-inch gun, model of 
1918, anti-aircraft, and a 3-inch auto-trailer carriage, model of 1917, 
mounted on an autotrailer. - 

The gun, of which there are two models, 1918 and 1918MI, is built 
up of nickel-steel forgings and consists of a tube, a jacket, and a 
breech ring, the latter being screwed to the rear end of the jacket 
forming a housing for the breech mechanism. Lugs are provided at 
the top and bottom of the breech ring to which are secured, respec- 
tively, the recoil cylinder and counter-recoil spring rods. The 19 18MI 
model differs from the 1918 model only in the jacket which is 1.6 
inches longer at the threaded part allowing a greater thickness of 
metal in rear of the jacket, thereby strengthening the gun around 
the chamber. 

The breech mechanism is practically the same as that used on the 
75-millimeter field gun, model of 1916 (American) (see p. 73), being 
of the drop block type, semiautomatic, and operated by a handle on 
the right side of the breech which is pulled backwards and down to 
open the breech. 

Weights, dimensions, and ballistics of gun. 

Weight of gun (including breech mechanism ). pounds . . 1, 966 

Caliber inches. . 3 

Total length of gun -do. ... 129. 69 

Length of bore : do 120 

Volume of chamber : cu. in . . 200 

Length of rifled portion of bore inches. . 95. 87 

Number of grooves 24 

Width of grooves inches. . 0. 2927 

Depth of grooves do 0. 03 

Width of lands do. ... 0. 10 

Muzzle velocity ft. per sec. . 2, 400 

Twist, right hand increasing from one turn to 50 calibers at the origin to one 

turn in 25 calibers at a point 8.87 inches from the muzzle and uniform from 

that point to the muzzle. 



332 

The carnage comprises the top carriage and cradle. The top 
carriage consists of two side frames bolted to a bottom plate which 
in turn rests on a circular roller frame and rotates about a pintle on 




VIEW OF RIGHT REAR OUTRIGGER WITH JACKSPADE AND FLOAT REMOVED AND 
BRACE DROPPED FROM SHACKLE AT INSIDE END; LEFT REAR OUTRIGGER IN 
POSITION, WITH FLOAT CONNECTION FOLDED. 

the base plate. The base plate is rigidly bolted to the trailer chassis 
and is equipped with outriggers and stability and lifting jacks which 
when in firing position, rest on detachable floats on the ground and 
support the entire weight of the carriage trailer. The top carriage 



333 



is prevented from tipping or lifting from the traversing rollers by a 
front and rear clip which are fastened to the bottom plate and which 
engage an annular flange on the base plate. 




The recoil mechanism is of the variable recoil hydro-spring type 
and operates the same as that of the 75-millimeter field gun, model 
of 1916. The only noticeable difference between the two is that a 



334 

spear buffer is used instead of a valve in the buffer rod head as is 
used in the 75-millimeter gun. The length of recoil varies from 16 
inches at 85 elevation to 40 inches at 10 elevation. 

An elevating arc having teeth is secured to the lower side of the 
cradle and meshes with a Hindley worm which is driven through 
bevel and spur gears by a handwheel located on the right side of the 
top carriage. 

The traversing mechanism is attached to the left side of the top 
carriage. The handwheel, through bevel gears, a worm, a worm 
wheel, and a friction clutch, rotates a pinion which in turn meshes 
with an annular rack bolted to the base plate. The pinion when 
rotated causes the top carriage to revolve about its pintle on the 
traversing rollers. 

Four seats are attached to the top carriage, two on either side, 
which are used by the personnel who operate the sights and elevating 
and traversing mechanisms. 

Platforms are bolted to both sides at the rear of the top carriage 
for the personnel who load and fire the piece. The platforms may 
be folded up and the seats swung to one side for traveling. 

When traveling, the gun is locked at an elevation of about 20 
and lengthwise of the trailer by upper and lower traveling locks for 
the purpose of taking up any strains or shocks which might come on 
the elevating or traversing mechanisms. 

Weights and dimensions of Carriage. 

Weight of carriage unit complete (including spare ammunition chest filled 

with ammunition, tools, and accessories) pounds . . 14, 085 

Weight of cradle (recoil cylinder complete, including oil, trunnions, gun 
slides, piston rod bracket complete, and spring cylinder with springs assem- 
bled) pounds . . 1, 2Q3 

Weight of trailer (with ammunition chest only, without tools and accessories 

or ammunition) pounds . . 4, 085 

Weight of trailer with carriage, gun, and ammunition chest only do 13, 200 

Weight under front wheels (fully equipped) do 7, 075 

Weight under rear wheels (fully equipped) do 7, 010 

Weight of one round of ammunition (complete) do 26. 8 

Maximum angle of elevation degrees . . 85 

Minimum angle of elevation do 10 

Traverse of carriage do 360 

Maximum length of recoil inches . . 40 

Minimum length of recoil do. . . . 10 

Number of rounds in ammunition chest 14 

Number of rounds in spare ammunition chest 16 

Height from ground to center of trunnions inches . . 85 

Height from ground to top of gun (in traveling position) do 119 

Maximum width of carriage do 77 

Maximum length of carriage (drawbar up) do 230 

Maximum length of carriage (drawbar down) do. . 243 



335 



CO 




18322820 22 



336 



The trailer upon which the carriage is mounted consists of two 
parallel side frames, between which are secured the cross members, 
bracing and making up the complete chassis. Between the front and 
rear wheels the frame is so depressed that the base plate of the car- 
riage is on the same plane as the hubs of the wheels, thus bringing 
the center of gravity of the carriage lower and lessening the possi- 
bility of overturning. The space at the front of the trailer formed 
by the side frames and cross members is provided with a bottom 




FRONT VIEW. 

plate, a top plate and hinged cover, and is utilized as a tool box. 
The rear section is similar to the front, except that a support is 
provided for the ammunition chest. The chest which carriqs 16 
rounds of ammunition also serves as a seat for the operators of the 
carriage. A foot rest is fastened to the rear tool box cover. The 
chassis is supported on the axles, both front and rear by semiellip- 
tical springs. 

The trailer is towed and steered by a drawbar equipped with a 
lunette and fastened to the front axle in such a manner that the 




(338) 



339 

trailer will actually follow in the path of the truck or tractor by 
which it is drawn. The trailer may also be steered by the rear 
wheels when the rear wheel lock is released and the steering bar is 
inserted. A pintle is provided on the rear end of the trailer to accom- 
modate any vehicles which may be attached thereto. 

This vehicle is equipped with a brake of the internal expanding 
type operating within drums attached to the rear wheels and applied 
and released by a lever on the right side of the trailer by one of the 
personnel seated on the ammunition chest. 

Weights and dimensions of Trailer. 

Wheelbase inches. . 156 

Width of track do 60 

Length of frame over all do 200 

Width of frame over all do 48. 125 

Weight of chassis pounds. . 3, 800 

Size of tires inches. . 37 

Width of tires .do 6 

Height from ground to center line of drawbar do 15 

Height from ground to top of frame, empty do 13 

Diameter of brake drum .do 16. 625 

Turning radius feet. . . 28. 6 

Road clearance under front axle inches. . 10. 281 

Road clearance under rear axle do 11. 375 

Height from ground to center line of pintle do 20. 5 

Over-all width at widest part do 77. 25 

Center to center at spring pads, front do 28. 5 

Center to center to spring pads, rear do 28. 5 

The sight issued for anti-aircraft carriages, model of 1918, consists 
of two units, one being mounted on the right trunnion of the cradle 
and the other on a bracket attached to the left side of the carriage, the 
two units being connected by a coupling shaft. The elements on the 
right side are the range and elevation corrector and those on the left 
side are the angle of site and deflection corrector. An open sight is 
attached to the sight proper for rapid location of the target. 

All necessary points for night firing are illuminated by the electri- 
cal equipment. A 6-volt system is used, the current being supplied 
by dry batteries, storage battery, or by a manually operated genera- 
tor. Small lamps of one or two candlepower shielded by reflectors, 
are used to illuminate the necessary scales and cross hairs. 



3-INCH ANTI-AIRCRAFT GUN MOUNT, MODEL OF 1917. 



The principle use of anti-aircraft artillery is mainly to hinder avi- 
ators from carrying out their missions. The destruction of airplanes, 
with the means actually at its disposal, is still a question of luck. 
Experience has taught aviators to defend themselves against fire by 
continual changes in direction. 

The earlier anti-aircraft artillery fire was directed by observation 
of the burst, but that eventually gave away to direction of the fire by 
carefully deduced principles. Nevertheless, the anti-aircraft artil- 
lery theory lays but little stress upon the possibility of inflicting 




GUN MOUNT IN ACTION. 



damage through a direct hit by the projectile which is fired from the 
gun, as it is considered that the possibility of such hit is too remote. 
The artillery practice is, therefore, to so direct the projectile that it 
will explode at a more or less predetermined position and cause 
damage either by the fragmentation of the projectile, which covers a 
very much larger volume than the intact projectile, or through the 
concussion caused by the exploding projectile and whose effects would 
also be felt through a considerable sphere. 

No one t}-pe of anti-aircraft gun carriage or mount can possibly 
satisfy all conditions of modern warfare. It is, however, possible to 

(340) 



341 




342 




343 



design a standard gun and top carriage having a wide range of action 
and by means of interchangeability enabling Jthis mount to be used 
on either a truck mount, a two or four wheel trailer, a caterpillar 
tread trailer, or as a semifixed mount, as each of these types of vehi- 
cles has its own sphere of action. However, the problem of seacoast 
defense and for the defense of depots, etc., led to the design of the 
3-inch anti-aircraft gun mount, model of 1917. 

The 3-inch anti-aircraft mount is of the barbette type, with con- 
stant recoil, designed to be mounted on a solid concrete base about 




VIEW SHOWING RIGHT SIDE OF MOUNT. 

30 inches thick and IS feet in diameter. The gun mount is designed 
to mount the 3-inch anti-aircraft gun, model 1917, 1917, MI, or 1917 
Mil, commonly known as the 1 5-pound er gun. 

The gun has a 12-inch recoil and a muzzle velocity of 2,600 foot- 
seconds. Both high explosive shell and shrapnel may be employed, 
the weight of the projectile being 15 pounds, and of the complete 
round of fixed ammunition being 28.38 pounds. 

The gun is mounted on a cradle of the sleeve type, which also 
serves as a housing for the spring and recoil systems. The cradle is 



344 

suspended by the trunnions from the top of the pivot yoke. The 
pivot yoke is bolted to the racer, which rests and revolves on 30 
rollers on the roller path of the base plate. The base plate is held 
in position in the emplacement by 16 anchor bolts set in the concrete. 

The field of fire is 360, to 90 elevation. Removable stops 
are provided, however, to limit the elevation of 85, due to possible 
injury to the personnel when the piece is fired at a higher angle. 

Fixed ammunition is used in these guns, consisting of a time-fuzed 
high-explosive shell, illuminating shell, tracer shell, and shrapnel. 
Each round consists of the cartridge case with its primer and powder 
charge; also the filled and fuzed projectile. 

Weights, dimensions, and ballistics. 

Weight pounds. . 3, 105 

Caliber inches. . 3 

Total length do.... 174.65 

Length of bore in calibers . 55 

Length of rifled portion of bore inches. . 137. 28 

Rifling: 

Number of grooves 24 

Width of grooves .'. inch. . 0. 2927 

Depth : do 0. 03 

Twist, right hand, 1 turn in 50 calibers atorigin to 1 turn in 25 calibers at 9.28 
inches from muzzle; thence uniform. 

Weight of projectile, filled and fuzed pounds. . 15 

Weight of charge do 5. 32 

Weight of fixed ammunition (1 round) do 28. 375 

Travel of projectile inches. . 139. 33 

Volume of chamber . cu. in . . 296 

Muzzle velocity ft. per sec. . 2, 600 

Maximum pressure per square inch pounds. . 32, 000 

Maximum horizontal range yards . . 12, 755 

Maximum vertical range do 9, 000 

The model of 1917 gun is built up of alloy steii, consisting of tube, 
jacket, and locking hoop. The jacket envelops the rear portion of 
the tube and forms the recess or seat for the breech mechanism. A 
r ecoil lug projects from the upper surface of the jacket near its 
extreme end and affords a point of attachment for the piston rod of 
the recoil cylinder. A lug also projects from the under surface, to 
which are attached the counterrecoil spring rods. The locking hoop 
is forced on the tube and forward end of the jacket, securing the 
latter against any rearward movement of the tube under firing 
stresses. 

The model of 1917 MI gun is similar in general construction to the 
model of 1917 gun, except that instead of the breech ring being 
integral with jacket, it is a separate piece. The breech end of jacket 
is threaded to receive the breech ring, which is screwed and shrunk 
on the jacket and held by a lock screw. The locking hoop is omitted. 



345 




346 




347 

The model of 1917 Mil is similar in general construction to the 
model of 1917 MI, except in the method of securing the latch plate 
to the gun. On the models of 1917 and 1917 Ml, the latch plate 
is secured to gun by screws, while on the 1917 Ml the latch plate is 
secured to gun by means of a lug. 

The breech recess is rectangular in shape. Two extractor trunnion 
seats, one in each side, are cut to the proper radius for the extractor 
to rotate and slide. Two holes are drilled from the rear face of the 
breech, one on each side, to accommodate a spring and plunger which 
press against the hub of the extractor, keeping it in place and also 
aids the extractor in ejecting the cartridge case. 

The breech mechanism consists of the following parts: Breech 
block, operating lever, operating handle, operating cam, operating 
cam cover, trigger shaft, extractors, firing mechanism, latch, and 
closing spring case. 

The breechblock is of the drop-block type and is rectangular in 
shape. Two grooves run lengthwise on the block, giving a wedging 
effect against the end of the cartridge case when the block is closed, 
and when opened insuring a clearance between the cartridge case and 
the block thus eliminating any chance of the cartridge case jamming. 
A venthole permits the escape of gas from a ruptured primer. 

Two extractor grooves, one on each side of the block, are cut 
parallel to the guide grooves and curve to a certain cam develop- 
ment which permits the proper action of the extractors. At the top 
of the block a radius is cut to permit of clearance when inserting the 
projectile. The toe of each extractor is cut to a radius which will 
just slide along the body of the cartridge when in place and engage 
the run of the cartridge case. 

The firing mechanism belongs to that type known as the con- 
tinuous-pull mechanism; that is, no cocking of the firing pin is re- 
quired other than a pull on the lanyard or trigger shaft. This 
arrangement permits of repetition of the blow from the firing pin in 
case of a misfire, as often as desired without the opening of the 

mechanism. 

Weights, mount, etc. 

Weight of mount only pounds. . 12, 175 

Weight of gun and mount do. ... 15, 280 

Weight of gun and cradle do. ... 7, 105 

Weight of cradle and recoil systems do. ... 4, 000 

Weight of yoke with elevating and traversing mechanisms do. ... 5, 100 

Weight of traversing rack, friction band, roller cage, and base plate do. ... 3, 000 

Weight of sight and supports do. ... 75 

The mount is emplaced in a concrete emplacement, in which 16 
anchor bolts are set, and depressions provided for 8 leveling screw 
thrust plates. A niche for an outlet box, through which electrical 
connections are made to the main base, or for a storage battery when 



348 

generated current is not available, is constructed in the concrete 
to meet the requirements of the mount. 

This emplacement is constructed by the Engineer Corps, which 
also furnishes and installs the necessary outlet or storage battery 
and furnishes the plug box portable lamp, cable, and plug. 

The principal parts of the mount are the base plate; racer; pivot 
yoke; cradle (containing recoil cylinder and counterrecoil mechan- 
ism) ; traversing mechanism, including traversing rollers and distance 
ring; elevating mechanism; firing mechanism; illuminating circuit 
and sight. 

The base plate is a circular steel casting which rests on the concrete 
emplacement with its upper surface machined to form the lower 
roller path. Sixteen holes, equally spaced around the circumference 
of the flange, are provided to receive the foundation bolts which 
retain the base plate in its proper position in the emplacement. A 
cylindrical projection in the center forms on its interior the housing 
for the 360 electrical contact, and on its exterior receives the trav- 
ersing rack. 

The racer is a circular steel plate, upon which the pivot yoke is 
bolted. The" under surface is machined to form the upper roller 
path, and the upper surface to fit the yoke. The racer rests on the 
rollers and rotates freely about the hub on the traversing rack. Two 
clips, front and rear, are bolted to the under side of the racer, and 
engage with a lug on the base plate to prevent the racer from leaving 
the rollers, and overturning the mount, when the gun is fired. 

The pivot yoke is a steel casting, consisting of two vertical side 
frames joined in front by a transom. At the top of each frame is a 
trunnion bearing and trunnion cap lined with bronze bushings. 
Tapped holes are provided in the left frame for the depression and 
elevation stop. The distance ring is a circular bronze ring provided 
with spaces and bearings for the traversing rollers. The traversing 
rollers, 30 in number, are interposed between the roller paths of the 
base plate and racer, bearing the weight of the mount. The rollers, 
roller paths, traversing rack, and pinion are protected from the en- 
trance of dust, sand or grit, by dust guards. The oil grooves on the 
circumference of the distance ring serve to distribute oil from the 
holes in the flange forming the base of the yoke to the axles of the 
rollers. A friction band, resting on the base plate, is made to grip 
the traversing rack. To adjust this band, which allows slipping 
of the traversing rack to protect the teeth of the traversing pinion 
from too heavy a stress, a cover in the base of the yoke is removed, 
giving access to the parts beneath. 

Motion of the mount in azimuth is obtained by a traversing pinion 
and shaft, the pinion meshing with the teeth of the traversing rack. 
Power is transmitted from the traversing handwheel to the traversing 



349 




350 




351 

worm, thence to the mount through a set of gears and a clutch 
mounted in the traversing gear case. Two speeds of traverse are 
possible upon throwing the clutch in by means of a handle, so that 
high or low speed gears are connected to the upper traversing shaft. 

The elevating mechanism consists of an elevating rack keyed to the 
underside of the cradle, having on its face teeth which mesh with the 
elevating worm. The rack is of sufficient length to provide for ele- 
vations from to 90. 

The cradle is bored and bushed to receive the gun. Front and rear 
liners are provided through which the gun slides in recoil. In addition 
the cradle forms the housing for the recoil and counterrecoil systems. 
The interior of the cradle has a cored recess to suit the firing mech- 
anism. 

Recoil mechanism is of the hydro-spring type. The recoil cylinder 
is screwed from the front into a seat provided in the top of the cradle. 
The piston rod is attached to the gun lug at one end and provided 
at the other end with a piston, slightly smaller than the bore of the 
cylinder. Three longitudinal throttling grooves are cut in the 
interior surface of the recoil cylinder, each groove subtending an arc 
of 30. With the cylinder in assembled position one groove is 
located at the bottom. The recoil cylinder has a capacity of 6J 
pints of hydroline oil. 

Two cylindrical holes bored in the cradle form the housing for the 
counterrecoil springs. Spring rods are attached at one end to the 
gun lug and at the other end to the spring-rod piston. When the 
spring compressor is first assembled it is secured against rotation by a 
retaining screw. The counterrecoil plunger, designed to check the 
recoiling parts as they return to battery, passes through the front 
end of the recoil cylinder and enters the recess in the forward end of 
the piston rod. 

When the gun is fired it recoils to the rear about 12 inches in the 
cradle, carrying with it the recoil piston and spring rods, thereby 
compressing the counterrecoil springs. A portion of the energy of 
recoil is taken up by the resistance the liquid offers to being forced 
through the variable slots formed by the throttling grooves and the 
constant clearances between the piston head and the interior surface 
of the cylindrical bore, the remainder of the energy being absorbed 
by the springs. The width of the grooves is uniform, but their depth 
is proportioned so that the areas of the orifices, varying with the 
position of the piston during recoil, will be such as to give, with the 
aid of the counterrecoil springs, a constant resistance throughout the 
length of recoil. The pressure in the cylinder is therefore a uniformly 
decreasing one. 

The counterrecoil buffer is tapered so that the escape of oil during 
counterrecoil, through the varying diametrical clearances between 
18322820 23 



352 

the plunger and the hole in the piston, will offer such resistance as 
will control the motion of the gun during its return to battery posi- 
tion after firing. 

The firing mechanism consists of a firing handle whose shaft passes 
through the center of the right trunnion and carries on its inner 
end a lever which operates the firing shaft. Previous to the firing 
the gunner pulls the firing handle which compresses the cocking 
spring solid and moves the lever on the breech to the tripping posi- 
tion; the gunner will know when the mechanism has reached this 
position by feeling the increased pressure exerted by the firing spring. 
To fire the gun, the gunner pulls the firing handle, compressing the 
firing spring, thus tripping the firing pin. The two-stage movement 
of the firing handle is intended to permit a shorter movement at the 
moment of firing. 

The illuminating circuit has a 360 contact mounted in the base 
plate. Direct-current mains of either 110 or 220 volts are connected 
with an outlet box located in the concrete emplacement. 

Two circuits are led from the 360 contact, one leading to the 
plug box for use as a portable lamp of line voltage, and the other 
circuit leads to the switch box; from here it is led to the rheostat 
from which two branch feeders are taken to the two receptacle boxes 
and bolted to the yoke. A circuit is taken from the right receptacle 
box with a spliced branch feeder to a candelabra receptacle for the 
reticule lamp and deflection pointer lamp. Another circuit is run 
from the left receptacle box with two spliced branch feeders to a 
candelabra receptacle for the elevation pointer, range disk pointer, 
and elevation correction lamps. These lamps are supported by lamp 
brackets fastened to the trunnion and sight mechanism. 

The rheostat used cuts down the voltage and makes the use of 
low-voltage lamps and batteries practicable in case the line voltage 
fails through accident. 

The cable leading from the 360 contact with the plug, switch, and 
rheostat is of the twin conductor, leaded, and armored type. The 
two branch feeders leading from the rheostat to the receptacle boxes 
and thence to the lamp brackets are of the portable conductor type. 
The various cables are fastened to the mount by means of cable 
straps and twisted hooks. 

Sight for antiaircraft mount, model of 1917. This instrument 
includes all parts used to direct the elevating and traversing of 
mount so that the gun may be pointed properly in elevation and 
direction. The parts consist of a sight proper (telescope), the sight 
mount, range disk, correction scale, and pointer. For any visible 
target the data necessary to properly lay the gun consists of fuse- 
setter range, travel in elevation and deflection, and the required 
arbitrary correction. 



353 

The target is brought into the field of view by turning the azimuth 
and the angle-of-site knobs, imparting to the sight a movement in 
azimuth and elevation, respectively. 

A scale is provided whereby the sight proper may be set in eleva- 
tion at any desired angle, whence the gun by means of the elevating 
mechanism is also elevated to the same angle (corrections being zero). 

An azimuth scale is also provided between the fixed and rotating 
parts of the carriage so that the gun by means of the traversing 
mechanism may be set at any desired angle in azimuth. 



75-MILLIMETER ANTI-AIRCRAFT TRUCK MOUNT. 

(MODEL OF 1917.) 



To appreciate the difficulty of anti-aircraft fire it suffices to con- 
sider that one is firing practically at a bird whose velocity is about 
50 meters per second, i. e., one-sixth the average velocity of the 
projectile itself in the case of the 75 -millimeter field gun. The 
principal result hoped for by the anti-aircraft artillery fire is to prevent 
airplanes from accomplishing their mission by obliging them to fly 
at increasing altitudes, to continually change their direction, and also 
to prevent their crossing certain regions. 

At the present time the anti-aircraft artillery aims to keep airplanes 
beyond the limit of their range. Observation airplanes are obliged 
to fly out of range, reconnoitering airplanes continually increase the 




TRUCK IN TRAVELING POSITION (RIGHT SIDE VIEW). 

height at which they cross the lines, and battle planes must also fly 
very high, except when they wish to attack trenches or batteries 
with machine guns. Raids of this kind are almost exclusively 
carried on at night. The result is that three kinds of fire have 
become particularly important: 

Fire against airplanes at a great range and a great height. 

Fire against very speedy airplanes attacking positions. 

Fire at night against bombarding airplanes. 

The need of an anti-aircraft weapon to meet the above require- 
ments led to the design of the 75-millimeter anti-aircraft truck mount. 
This development involved the use of an American model 1916 field 
gun, equipped with a hydro-spring recoil mechanism having throttling 

(354) 



55 




356 



1 




357 

valves cut in the cylinders. This gun and recoiling mechanism is 
secured on an offset swivel gun mount, suitably mounted on a 2J-ton 
White gasoline-driven truck, Model TBC, designed to receive the 
base plate of the top carriage. 

The gun (see p. 72) is carried on a cradle which rocks in elevation 
about the trunnions of the top carriage, and, by means of the elevating 
mechanism, a range of elevation from 31 to 82 is obtainable. The 
piece has a recoil of 33 inches on its cradle and is provided with a 
recoil cylinder, counter-recoil springs, and buffer. 

The piece has a muzzle velocity of 1,830 feet per second, and uses 
high-explosive and shrapnel shells, the former weighing 14.7 pounds 
and the latter 14.3 pounds, employing a 20-second (maximum) time 
fuze with each. With a maximum vertical elevation of 82 a 
vertical bursting ordinate of 5,980 meters is obtained, and with the 
minimum elevation of 31 a vertical bursting ordinate of 1,750 




VIEW SHOWING TRUCK MOUNT IN ACTION. 

meters is obtained. In both cases the bursting ordina^es were 
limited by the time fuze. 

The gun with the breech is located directly behind the driver's 
seat, but as the length of recoil is fixed, the firing position is limited 
to such horizontal position of the mount as would permit of the gun 
recoil clearing the sides or rear of the truck chassis. 

A heavy base plate is secured to the rear end of the chassis, and 
the top carriage swings in azimuth about a central pintle bolt on 
rollers. By means of the traversing mechanism, the carriage, 
carrying the gun and its corresponding mechanism, can be traversed 
through 240, which is the field of fire. The chassis is equipped with 
firing and stability jacks to relieve the rear springs and truck of all 
firing strains. With the jacks properly placed and leveled, the 
vehicle is supported on a rigid horizontal platform formed by the 
firing jacks and the base plate. When in action the stability equip- 
ment .functions to prevent the mount from overturning when the 
gun is fired at low angles of elevation. 



358 

Weights, dimensions, and ballistics. 

Caliber inches.. 2.953 

Total length of gun do 90. 9 

Length of the rifled portion of the bore do 72. 72 

Length in calibers 28. 4 

Weight of projectile: 

Shell pounds. . 14. 7 

Shrapnel do 14. 3 

Weight of full powder charge do 1. 625 

Service muzzle velocity feet per second . . 1, 830 

Horizontal range at 45 elevation (14.3-pound shell) yards. . 10, 595 

Maximum elevation degrees. . 82 

Minimum elevation do 31 

Total traverse do 240 

Weight of gun and breech mechanism pounds. . 750 

Weight of gun, breech mechanism, and carriage do 3, 300 

Weight of chasis, including attachments and accessories do 4, 500 

Weight of top carriage, and its corresponding mechanism, etc do 4, 250 

Total traveling weight of unit (fully equipped) do 9, 500 

Overall length of vehicle (traveling position) inches . . 209 

Overall width of vehicle (traveling position) do 74$ 

Weight of chassis only (without attachments) pounds . . 4, 100 

Wheel base inches. . 157$ 

Wheels, front do 36 x 4 

Wheels, rear do 36 x 7 

Road clearance do 9$ 

Rating of load tons. . 2$ 

Tread inches . . 62 

The principal parts of the carriage are: The base plate, top carriage, 
recoil mechanisms, cradle, elevating and traversing mechanism, 
angle of sight mechanism, firing jacks, stability jacks, and rails. 

The base plate is a rectangular steel casting secured to the truck 
chassis, and, serves as a support for the top carriage. The traverse of 
the top carriage is limited by lugs provided on the top of the clip 
surface. The clip prevents the traversing rollers from leaving their 
path due to the shock caused by action of recoil or counterrecoil. Four 
lugs radiating from the pintle bearing serve as points of attachment 
for the firing jacks and rail tie rods. At the forward end of the base 
plate are two lugs, one on either side, which project out at right 
angles to the truck chassis, serving as points of attachment for the 
stability jacks. The firing strains produced during action are 
transmitted through these lugs and jacks, thus eliminating all unneces- 
sary strains from the rear springs and wheels of the truck. 

The top carriage is a steel casting, comprising a base and two vertical 
side frames designed to mount the cradle to permit sufficient clearance 
for the recoiling parts at high angles of fire. A pintle bolt projecting 
from the base plate through the case of the top carriage forms an axis 
about which the carriage is rotated in azimuth upon four rollers resting 
on the roller path of the base plate. Between the two side frames is 
housed the angle of sight mechanism. The traverse of the carriage 



359 

is limited to 240 by means of a traversing stop plunger, which 
engages the lugs on the clip surface. When preparing for travel the 
stop plunger can be raised to clear the limit stop, thus permitting the 
proper position of carriage when en route. Four seats (two on each 
side) riveted to swinging arms, for the use of the cannoneers during 
action, are secured to the top carriage. 

Recoil mechanism. The recoil mechanism is of the hydro-spring 
type, with recoil cylinder mounted above the gun. Three longitudi- 
nal ribs, or throttling bars, of uniform width but varying height, are 
formed on the inside of the cylinder and engage with corresponding 
grooves in the piston head. The clearance between the bars and 
grooves determines the amount of oil which may pass from the back 
to the front of the piston head, thereby regulating the amount of recoil. 

The piston rod is a hollow steel tube and is fitted with a bronze 
head. The rear end of the piston rod is bored out to accommodate 
the counterrecoil buffer, which fits into the bore with a small clearance. 
This clearance depends on the taper of the buffer, as the hole in the 
piston rod is of constant diameter. 

In each spring cylinder, three coils of inner and outer counterrecoil 
springs are assembled over the spring rod. The inner and outer 
springs are wound in opposite directions to prevent nesting, and each 
pair of inner springs is separated from the next pair by a bronze 
separator. 

When fired, the gun moves back on its slides carrying with it the 
recoil cylinder and counterrecoil springs. The piston rod is secured 
to a nonrecoiling part of the carriage, thus when the recoil cylinder 
moves to the rear, the oil in it must pass from one side of the piston to 
the other. The energy of recoil of the gun is absorbed by the resist- 
ance which the oil offers to being forced through small openings past 
the piston, also by the compression of the counterrecoil springs. The 
energy stored up by the springs returns the gun to battery position. 
The return movement is eased and regulated by the counterrecoil 
buffer, which prevents any undue shock to the recoiling parts by 
offering resistance due to the fluid in the hole of the piston rod being 
forced out as the buffer gradually enters the hole. 

The cradle comprises the counterrecoil spring cylinders with their 
component attached parts. The spring cylinders are below the gun 
and in the form of two cylinders joined at the center. Above the 
cylinders are the bronze lined gun ways or slides. The trunnions 
are secured to the cylinders, and the elevating arc is bolted to lugs on 
the bottom. Riveted to the right side of the cradle is the elevation 
stop and the depression stop. 

The rocker, a U-shaped forging, is journaled upon the trunnions. 
Bearings are provided in the bottom of the rocker for the elevating 
mechanism and a rack is cut on the exterior of its yoke for the angle 
of sight worm. 



360 

The traveling lock is located under the rear end of the spring cylinder. 
This device functions to lock the cradle at an angle of approximately 
32 in elevation when preparing for travel, thus the elevating angle of 




GUN MOUNT SHOWING GUN AT MAXIMUM ELEVATION. 

site and traversing mechanisms are relieved of all unnecessary vibra- 
tions when the vehicle is en route. At the front end of the base plate 
is hinged a lock bar and brace, which engage a lug provided on the rear 



361 

end of the cradle. In order to bring this lug in proper position to 
receive the lock bar, the cradle must be traversed to its traveling posi- 
tion, that is, to bring the axis of the gun into a vertical plane with the 
center line of the truck chassis. 

The elevating mechanism consists of an elevating worm, an elevating 
arc or rack, and a train of miter gears mounted on the right side of the 
rocker. The shaft on which the elevating handwheel is mounted 
extends through the side frame of the top carriage. 

The worm is operated through gears and a shaft by means of a 
handwheel, and rotates the cradle about the trunnions. Any move- 
ment imparted to the worm by the handwheel will cause the cradle 
to move with relation to the top carriage. One turn of the hand- 
wheel will cause the gun to be elevated or depressed approximately 




TRUCK IN TRAVELING POSITION (LEFT SIDE VIEW). 

1.7. The elevating arc permits a change of elevation from 31 mini- 
mum to 82 maximum. 

The traversing mechanism located on the left side of the top carriage* 
consists mainly of a traversing handwheel and shaft, worm, worm 
wheel, clutch, bevel pinion, traversing pinion, and rack. The worm 
engages the worm wheel and can be either engaged with or disen- 
gaged from the shaft by means of a clutch operated by a foot lever. 
If the clutch be disengaged, the worm and worm wheel are released 
from the gear train, and the top carriage may be traversed about the 
pintle bolt by hand. The traversing pinion engages the traversing 
rack which is secured to the base plate. One turn of the handwheel 
will cause the gun to be traversed approximately 2. 

The angle of site mechanism consists of a handwheel, handwheel 
shaft, and angle of site worm. The angle of site worm is secured 
to the top carriage and engages in a rack cut in the face of the yoke of 
the rocker. To one end of the shaft which extends out to the right 



362 

side of the top carriage is secured the handwheel and to the other end 
is fixed a miter gear. 

The angle of site worm is a one-piece forging comprising a worm, 
a shaft, and a miter gear of the same size as that on the bracket at 
an angle of 90 to the handwheel shaft and with the miter gears at, 
the ends in mesh. One turn of the handwheel will cause the rocker 
and the cradle to be elevated or depressed approximately 25 mils. 
The rocker allows a correction of 124 mils depression and 200 mils 
elevation. 

Firing and stability jacks. The principal parts of the firing jacks 
are the jack body, jack screw, foot, and spade. There are two firing 
jacks, the bodies being hinged at the rear corners of the base plate 
as shown on page 363. At the end of the jack screw the foot, or float, 
is secured by a ball joint which enables the jack to be seated on 
inclined surfaces. The foot is provided with a sharp-pointed spade, 
which is driven into the ground. A tie rod is used between the two 
jacks to keep the jack bodies from spreading out when the load is 
put on the screws. The firing jacks act as rigid supports for the base 
plate at the rear corners, and relieve the truck chassis of firing strains. 

The stability jacks are essentially the same in construction as the 
firing jacks, but heavier. Their function is to prevent the overturn- 
ing of the truck when the gun is'fired at low angles of elevation, and 
also to take the firing strains. The stability jacks are hinged to the 
base plate, one on each side and each is supported by a strut hinged 
in a lug secured to the truck chassis. The stability jack floats are 
provided with spades. 

When the carriage is in the traveling position, the firing jacks and 
stability jacks are folded up and secured by chains. The spades are 
removed and placed in receptacles provided on the chassis. The 
stability jack struts are unpinned from the forward lugs, removed 
and carried in holders on the base plate. The tie rods are folded 
with the jacks and chained in position. 

Two stability rails and tie rods are provided with each mount, one 
being straight and the other having an offset. They are crossed 
under the rear axle of the truck, the rear ends being located so that 
the firing jack floats set in the spaces between the angles of each rail. 
The middle angles at the front ends of the stability rails are attached to 
the stability rail tie rods, which in turn are connected to the adapters 
on the lugs, directly opposite the firing jack lugs, on the base plate. 

When the vehicle is to be emplaced, both of the truck wedges are 
placed on the ground with the channel side up, and the front wheels 
of the truck are run up the channels between the flanges. The pur- 
pose of these wedges is to raise the front end of the truck so that the 
mount will be level when the rear end is jacked up. Two steel 
blocks are provided for blocking the front wheels when they are run 
up on the truck wedges. 



363 

Rear axle slings. When traveling, the slings hang loosely under 
the truck, one on either side of the transmission. The front ends of 
the slings are looped around through holes in the base plate and 
clamped in place permanently. Two steel rods are inserted in the 
rear loops of the slings and placed across the rear end of the chassis 
when the mount is emplaced, and two pieces of pipe are inserted in 
the front loops of the slings and placed across the ribs on the front 
end of the base plate. The purpose of these slings is to keep the 




FIRING AND STABILITY JACKS. 

rear springs compressed and the rear wheels off the ground when the 
mount is jacked up. 

The electrical equipment consists of five lamps receiving current 
from a storage battery, suitable wiring, and switching arrangements. 

Two three-cell, 6 to 8 volt batteries are provided, one for reserve, 
each of 120-ampere-hour capacity, and are carried in a metal con- 
tainer which is bolted to the chassis of the truck. One battery, 
when fully, charged and in good condition, will furnish energy for 
about 24 hours' continuous service for all lamps. 



364 

All wiring is permanent and the connecting wires are protected by 
steel armor wherever mechanical injury is likely. Should it be 
necessary to remove the top carriage, the lead from the battery 
which runs through the pintle bolt may be disconnected above the 
top of the bolt by unwrapping the insulation and opening the con- 
necting plug there provided. 

The lamps are specially designed to withstand the shock of firing 
and are rated at 2 candlepower. One lamp is provided for illuminat- 
ing each of the following parts : 

Deflection correction pointer. 
Keticule. 

Elevation pointer. 
Range disk pointer. 
Elevation correction pointer. 




TRUCK MOUNT IN BATTERY POSITION. 

A snap switch is provided in the main battery lead which controls 
all the lamps, and the lamps should be disconnected by means of this 
switch when not in use. 

The sight for this antiaircraft vehicle is an instrument which in- 
cludes all parts used to direct the elevating and traversing of the 
mount so that the gun may be pointed properly in elevation and 
azimuth. The parts consist of a sight proper (telescope), the sight 
mount, range disk, correction scale and pointer. For any visible 
target, the data necessary to properly lay the gun consist of fuze 
setter range, travel in elevation and deflection, and any desired 
arbitrary correction. 

The object is brought into the field of view by turning the azimuth 
and the angle of site knobs imparting thereby to the sight a move- 
ment in azimuth and elevation respectively. The object is followed 
by continuing the movement of these knobs. Detailed description 
of the model 1917 anti-aircraft sight may be found in separate 
pamphlet covering fire-control instruments. 



TRENCH WARFARE MATERIEL. 



The trenches constitute the most advanced position of a combat 
army and the equipment and supplies placed at the disposal of those 
occupying them are generally classified under the broad heading of 
" Trench warfare materiel." 

The trench forms protection against horizontal firing and permits 
of secret massing of troops for surprise attacks, and it is the constant 
aim of the Air Service, with its photographic equipment and tele- 
graphic communications, to reduce this element of surprise. Con- 
cealment of the general outline from airplane observation is impos- 
sible, but details may be concealed, for an observer in an airplane 
can not see whether a trench is occupied unless the airplane flies 
dangerously low. 

The trenches are carried up to within 200 yards or less of the ene- 
my's front line and are the scene of constant watchfulness to prevent 
enemy advance and of constant attempts to reduce the enemy per- 
sonnel, lower his morale, capture prisoners for the purpose of obtaining 
information, and to advance the position of our own lines. 

The field artillery is located from 1 to 5 miles or more behind the 
front line, in order to protect it from sudden rushes by the enemy, 
while the infantry, machine gun, and trench mortar personnel occupy 
the trenches interlaced through the intervening terrain to afford this 
protection and also to place the personnel of the army in a position 
to come into contact with the enemy without being obliged to pass 
over a wide intervening stretch of terrain under enemy fire. 

The operation of all branches of the service are interrelated, and 
nothing is haphazard or independent of the comprehensive plan, 
save during the heat of action or in the event of units becoming 
isolated, and such movements are temporary only in their inde- 
pendence, as their effects are consolidated with the complete plan 
so soon as opportunity permits. The air service, field artillery, the 
signal service and the tanks are all coordinated through headquarters 
with the service of the trenches and communication is maintained 
through an elaborate system of telephone and telegraph wires, pyro- 
techinic flashlights, flare, or other visual signals. 

The trench system includes a front-line trench of broken line for- 
mation, whose individual straight lines are from 9 feet to 18 feet in 
length. An enemy entering this trench can sweep only the length of 

(365) 



366 




TRENCH WARFARE. 



367 

the straight line, and must fight around a barrier for the balance of 
the trench. This trench is connected by communication trenches 
to a supervision trench located to the rear, and thence by other 
trenches, possibly several miles further back, into friendly territory. 
The communication trenches are curved, elbowed or zigzagged and 
have T or L connections, island pockets, tunnels, bombing pits, 
strong points, keeps, shelters, dugouts, or other provisions as the 
conditions may demand. 

Traps are arranged for the confusion of an enemy entering the 
trench, positions are arranged for dropping barbed wire, knives, or 
frames quickly into position to retard the advance of the enemy 
troops who have gained the trench. Machine gun and mortar em- 
placements are built where needed and bomb-proof dugouts pro- 
vided for rest quarters, storage and forward dressing stations for the 
treatment of wounded. 

The narrower a trench is the better the cover which it affords. 
Communicating trenches are made of sufficient width to permit of 





ARRANGEMENT OF TRENCHES. 



the carrying of stretchers, and thus allow for the evacuating of the 
wounded during daylight. The wider trench submits it to greater 
effect from enemy artillery fire, but if trenches are not wide enough 
for stretchers, losses result through the detention of casualties in 
the trenches until darkness permits of their removal to dressing sta- 
tions. The wider trench also permits a more rapid movement of 
men and supplies between the front line and rear areas, and thus 
reduces the time during which men and supplies are detained under 
concentrated fire, and hence reduces the casualties and destruction 
from this cause. 

Gas is a constant menace in the trenches, as it is heavier than air, 
and its effects vary with the nature of the gas employed. Flame or 
liquid fire is employed both with a view to inflicting injury to the 
enemy and lowering his morale. The presence of water is always 
taken into consideration, for the trench is open to water resulting from 
rainfall. Provisions are made for footing and drainage, advantage 
being taken of natural slope where possible. 
183252820 24 



368 

Trench warfare has shown the necessity for hurling large charges of 
high explosives for comparatively short ranges. This necessity has 
led to the development of the trench mortar, a type of weapon that 
is a short smooth bore of simple construction. They are muzzle 
loaders and use as their projectile a thin- walled shell, known as a 
trench-mortar bomb. 

In trench warfare the role of trench artillery is to harass the enemy 
by engaging living targets where opportunity offers, to attack and 
destroy enemy defensive works and obstacles within range limits, 
and to prevent the construction of new works. 

The trench mortar is essentially a trench artillery weapon of limited 
range which will render very efficient service when properly emplaced, 
skillfully handled and served. 

The trench mortars are divided into three classes, light, medium, 
and heavy calibers. 

The light trench mortar is very mobile. Its effect against material 
is inconsiderable, but is particularly effective against massed troops, 
or troops driven into the open, due to its rapidity of fire. These mor- 
tars are used to form a barrage behind the hostile line to prevent 
reserves and ammunition being brought up. Owing to their high 
mobility, limited only by the difficulty of ammunition supply, they 
are especially fitted to accompany the infantry as it advances, and 
are used to attack machine-gun shelters and other points which have 
temporarily checked the forward movement of the infantry. 

The medium trench mortar, with its range of approximately 1,200 
meters, is very effective against wire entanglements, machine-gun 
shelters, strong points, trenches, and other similar objectives not 
too strongly protected. 

The heavy trench mortar is designed for the attack of heavily pro- 
tected shelters and dugouts, trenches, machine-gun shelters, and 
strong points. It is seldom used against wire entanglements because 
of the large crater formed by the explosion. 

In most types of trench mortars the propelling charge is carried 
at the base of the bomb and is ignited by striking a pin at the breech 
of the piece. The bomb is dropped into the muzzle and slides down 
by its own weight until the firing pin ignites the charge. 

The types now issued to the service are : 

3-inch Stokes trench mortar, Mark I. 
6-inch trench mortar, Mark I. 

The characteristics of each type will be discussed on the following 
pages. 



3-INCH STOKES TRENCH MORTAR (MARK I). 



The 3-inch Stokes trench mortar is of British origin, and proved a 
very useful and excellent weapon owing to its simplicity, light weight, 
and the principle of auto-ignition. Its principle has practically been 




copied by both the French and our 'armies and applied to other 
mortars. 

The mortar essentially consists of the following components: A 
smoothbore barrel, a bipod, and base, the complete unit weighing 
108 pounds. The barrel is a seamless drawn steel tube, lapped to 

(369) 



370 



size and necked down at one end and called the breech or base end. 
To the breech end is fitted a base cap, within which is secured a 
firing pin protruding into the barrel. The barrel is supported near 
the muzzle end, by a steel bipod fitted with elevating and traversing 
screws. The recoil of the mortar is taken up by a base plate against 
which the base cap of the barrel rests. 




FRONT VIEW OF TRENCH MORTAR. 

The elevating stand is made of tubular steel, consisting of two 
legs attached to a center trunnion by means of a compass joint; these 
legs are held apart by a cross stay which is arranged to spring just 
past the dead center in such a manner as to hold the two legs rigidly 
apart. The trunnion standard is fitted with a pair of bevel gears 
operated by a handle, by means of which the elevating screw can 
be rapidly raised or lowered. The upper end of the elevating screw 
is fitted with a yoke to support the transversing screw shaft, which, 



371 

together with a traversing handle and a dog clutch, forms a bolt 
and is held in position by a locking pin. A traversing screw carried 
by the traversing screw shaft and driven by the dog clutch forms the 
means of traversing the mortar by engaging a nut fixed to the barrel. 
The barrel can be quickly disconnected from the mounting by lifting 
the locking pin and withdrawing the traversing bolt. The barrel may 
then be lifted out of position. 

The base plate has three depressions. The shape of the base cap 
permits the lower end of the barrel to rest in any of these depres- 
sions, and by shifting the barrel from one to another a change of 6 




REAR VIEW OF TRENCH MORTAR. 

in direction of line of fire can be made on either side of the center 
position. 

In firing position the base plate is embedded in the ground at 
about a 45 angle. The lower end of the barrel is placed in the 
indentation in the base plate which gives the barrel the direction 
nearest to that desired, the upper end of the barrel being supported 
by the legs of the bipod. Minor adjustment for direction is secured 
by means of the traversing screw. The barrel is then given the ele- 
vation corresponding to the desired range by operating the elevating 
screw. The range quadrant (or clinometer) , being set for the desired 
range, indicates when the barrels has the proper elevation. 



372 

The shell or bomb used with this mortar is a cylinder loaded with 
high explosive, fitted at its head with a detonating fuze. The weight 
of the shell is approximately 11 J pounds. The propelling charge 
consists of 12-gauge shotgun shell, which fits in a cartridge container 
at the rear end of the shell. To secure additional range, 1 to 3 rings 
of ballistite can be placed around the cartridge container. The 
range secured with cartridge alone varies from 150 yards at 75 
to 300 yards at 40. With cartridge and three rings, the range 
reaches a maximum of 750 yards at 40 elevation. 

The firing operation is as follows : The shell with propelling charge 
in position (the cartridge inserted in the cartridge container and the 
rings around the container) is dropped into the muzzle of the mortar, 
cartridge end first, and slides down the barrel. The primer of the car- 
tridge is fired on impact with the firing pin. Ignition of the ballistite 
rings is obtained from the flash of the cartridge through ports in 
the cartridge container. The shell, carrying the cartridge case with 
it, is projected from the barrel and the mortar is ready for another 
shell. 

The extreme rate of firing under average conditions is about 25 
rounds per minute, but 10 rounds per minute is considered the 
average effective rate. The crater formed by the shell has a depth 
of about 2 feet and a diameter of about 4 feet. 

Weights of mortar. 

Pounds. 

Barrel, ring, clamp, traversing screw, and base cap 43 

Bipod (mounting complete) 37 

Base plate__ 28 



6-INCH TRENCH MORTAR (MARK I). 



This mortar is an American adaptation of the British 6-inch 
Newton trench mortar. It is operated by dropping the shell down the 
barrel of the gun and thus igniting the propellent. While the prin- 
ciple of firing is the same as in the 3-inch Stokes mortar, the mount- 
ing is somewhat different, in that no bipod is employed; the breech 
end of the barrel resting on a cupped base plate and being supported 
in an overhanging position therefrom by three guy rods. This 
weapon is a most effective agent against machine-gun nests, barbed- 
wire entanglements, fortifications, etc., but is seldom used against 
personnel. 

This mortar consists of the following essential components : 

Barrel with clinometer. 

The platform, base, guys, and fittings. 

The sub-base. 

The barrel is of one piece, muzzle loading, having a smooth bore. 
The breech is closed and rests in a hemispherical socket supported 
upon a stationary platform to which the barrel is stayed by three 
adjustable guys. The elevation, which varies from a maximum of 75 to 
a minimum of 40, and lateral deviation is made by altering the length 
of the guys, which are adjustable by means of handwheels. These 
adjustments are determined by the setting of the clinometer attached 
to the barrel. The range can be varied by changing either the eleva- 
tion of the gun or the weight of the propelling charge. 

The setting up of this mortar is a more elaborate proceeding than 
the setting up of the 3-inch Stokes mortar. The cast steel base is 
bolted to a hardwood platform, which is mounted on a sub-base made 
up of timbers and a rectangular iron frame bolted together. The sub- 
base may in some cases be dispensed with, as shown on page 373. 

The barrel is furnished internally at the breech end with an axial 
firing pin or anvil and externally with a guide stud and a misfire 
plug. Should the ignition cartridge fail to function when the shell 
is dropped down the barrel, the misfire plug permits of the intro- 
duction of a small powder charge with fuze for the ignition of the 
propelling charge. Graduations are engraved on the barrel on the 
right and left of a zero line and are used for traverse setting of the 
clinometer. 

(373) 



374 






375 

The base is a steel casting having a machined hemispherical socket 
on the upper side to receive the rounded end of the barrel and pro- 
vided with a guide groove which engages the guide stud on the barrel 
when in position. 

The base is bolted to the hardwood platform. Elevating and 
traversing guys are anchored to the upper side of the platform, while 
the free ends of the guys are hooked into devices on the barrel when 
the latter is mounted on the base. Special hooks provide a method 




LEFT SIDE VIEW OF 6-INCH TRENCH MORTAR. 

of fastening the guys during transportation. Four wire-rope han- 
dles are provided as a means for carrying the platform. 

The clinometer consists of a quadrant graduated with an elevation 
scale and straddled by a bubble carrier which oscillates about a center 
on the quadrant. The bubble carrier is provided with a pair of cross 
bubbles. The clinometer is attached to the mortar barrel by steel 
bands and a clamping screw. 

In laying of the piece, an arrow on the quadrant is set to coincide 
with the desired traverse and the indicator on the bubble carrier is 
also set coincident with the desired elevation. The guys are then 



376 

adjusted so that both bubbles are exactly level, the barrel of the gun 
in the desired direction. 

The gas ejector consists of a metal head to fit the bore and a tube 
at one end of which is a handle. When the gase ejector is pushed down 
the barrel the burned gases are forced up through the handle and 
out of the gun. When the gas ejector is removed cold air is sucked 
through the handle and into the gun. The head is threaded to 
receive a wire brush or a sponge head whenever it is desirable to clean 
or sponge out the bore. 




METHOD OF LOADING TRENCH MORTAR. 

The projectile is a cast iron fragmentation shell with vanes, weigh- 
ing approximately 42 pounds unloaded, and containing a bursting 
charge of approximately 11 pounds of high explosive. The pro- 
jectiles are fitted with delay and nondelay fuzes. 

The propelling charge consists of sporting ballistite contained in 
silk bags of 1 and 2 ounces capacity. With these two sizes of bags 
a number of combinations can be obtained and the range can be 
varied according to these combinations. The maximum charge is 



377 

9 ounces and the minimum 3 ounces. The bags are held in place 
between the vanes of the shell by a propelling bag holder. The 
charge is ignited by an ignition cartridge made from a standard rifle 
cartridge which is fired when it strikes the firing pin as the shell 
reaches the bottom of the barrel. 




REAR VIEW OF MORTAR. 

Weights, ballistics, etc. 

Overall length of barrel inches. . 57 

Weight of barrel pounds. . 162 

Weight of base do 75 

Weight of platform do 160 

Weight of sub-base do 530 

Weight of shell, loaded (approximately) do 53 

Weight of shell box do 10 

Range, minimum meters . . 200 

Range, maximum do 1, 700 



PROSPECTUS. 



The trend of design for field artillery now proposed and under way 
shows several digressions from the present practice. 

Motor transportation promises to almost completely revolutionize 
artillery design. A motor-drawn carriage is not so limited in weight 
as the horse-drawn type, thus permitting heavier and more powerful 
weapons. At the same time the carriage must be designed to with- 
stand the more severe usage of motor traction. 

A further development along the line of motor transportation is the 
self-propelled caterpillar mount for field artillery. The performance 
of the experimental mounts of this type has been very satisfactory, 
and no doubt manufacture in quantity will be ordered in the near 
future. The piece is mounted with a suitable top carriage directly 
on the caterpillar, and thus forms a self-contained unit capable of 
rapid and easy maneuvering. This type of mounting permits of 
carrying various calibers of guns and howitzers, and has the further 
advantage of permitting all around traverse by maneuvering the 
vehicle under its own power. They are also able to negotiate rough 
and difficult terrain more readily than any other type of vehicle yet 
developed. 

The self-propelled caterpillar, Mark II, 8 units of which have been 
recently issued to the service, is a road vehicle of the track-laying 
type; that is, the power is transmitted to the ground through a 
flexible, endless track composed of steel shoes, instead of directly 
through the drive wheels as in the usual type of truck construction. 

This caterpillar has been designed and constructed to mount the 
155 mm. gun, and be able to withstand its firing stresses. Although 
not primarily a hauling or towing type of machine, it is provided with 
a rear pintle for towing an ammunition trailer or similar vehicle. On 
each side at the front of the main frame draw hooks are provided for 
towing the mount when necessary. 

The various units composing the vehicle are assembled on the main 
frame which is a rigidly reinforced steel casting. The main frame is 
supported on the track by truck roller frames on which it rests 
through the medium of an equalizing mechanism and spring buffers. 

The power unit of this vehicle is mounted longitudinally at the 
forward end beneath the muzzle end of the gun, consisting of a 
Sterling U FT" six-cylinder internal combustion engine with its fuel, 
carburetion, ignition, lubrication, and cooling systems. 

(378) 



379 

The power developed is transmitted to the drive sprockets, which 
drive the track through the following power system. A master clutch 
controls the application of power between the engine and main trans- 
mission unit containing selective gears by which the speed and direc- 
tion of travel are controlled. From the transmission unit the power 
is transmitted to two propeller shafts through the steering clutches 
and reducing planetaries. These propeller shafts transmit the power 
from the intermediate transmission to the final drive gears on the 
drive sprockets. 




PLAN VIEW OF SELF-PROPELLED CATERPILLAR, MARK II. 

The driving mechanism is so designed that the forward travel of 
the vehicle is the pointing 'direction of the gun. The combination of 
selective and planetary gears provides four speeds forward and two 
reverse. The direction and speed of travel are under the direct con- 
trol of a single operator, seated where he is able to obtain full view 
ahead and may readily gain access to engine in case of emergency. 

The planetary brake, the master clutch, and the gear shift are 
operated by hand levers. The planetary brake and steering clutch 
on the same propeller shaft are operated by the same lever. Having 
a separate lever for each propeller shaft the steering clutches and 
planetaries can be operated separately or simultaneously, as desired, 
and in this way the vehicle is steered. 



380 

When both steering levers are in the forward position, the steering 
clutches are engaged, and power is transmitted to both tracks at the 
direct speed. By placing the right steering lever in the central or 
neutral position, the right steering clutch is disengaged and power is 
transmitted to the left track only and the vehicle can be made to turn 
sharply to the right by applying the right steering clutch brake. 




Placing the right steering clutch lever in the rear position sets the 
planetary brake and reduces the speed of the right so that the 
vehicle turns slowly to the right. In a similar manner the vehicle 
can be turned to the left by the use of the left steering lever. Apply- 
ing both planetaries at the same time furnishes a reduced uniform 
speed to both tracks and a low gear ratio for a hard pull. With both 



381 

steering levers in neutral, or with the master clutch disengaged, both 
brakes may be set simultaneously by the use of the hand lever located 
between the two foot brake pedals. The speed and direction of the 
direct drive is controlled by the selective transmission gear-shift lever, 
which can only be operated when the master clutch is disengaged, 
thereby breaking the power between the engine and the transmission. 




The steel deck plates directly over the transmission case, planetary 
brakes, and steering clutches are removable to provide ready access 
for repairs and adjustments. Doors are provided in the sides of the 
armor plate engine hood for the same purpose. 

The equalizer arrangement is pivoted at the front end of the main 
frame and operates so that one track, when passing over a log or 



382 

obstruction, forces th.3 track on the opposite side down into firm, 
bearing with the ground, thus preventing the caterpillar tipping 
sideways, or the front end riding up and running down with a jar 
when the center of gravity passes over the obstruction. The forward 
end of the caterpillar is covered with steel plates forming a protecting 
nose when forcing its way through brush, trees, and other field 
obstructions. 

The rear deck plates under the gun breech are hinged so that they 
may be folded back out of the way to enable the gun crew to load and 
handle the gun from the ground. 

A traverse of the gun relative to the caterpillar of 5 to the right 
and 5 to the left is provided, which is sufficient for corrections and 
accurate pointing. Any necessary traverse beyond this limit is 
obtained by traversing the caterpillar vehicle under its own power by 
the use of the steering levers. Under ordinary ground conditions an 
all around traverse can be obtained in this way. The to 35 range 
elevation of the standard wheeled carriage is retained in this mount. 

A structural steel deck, with necessary guard railing is secured to 
side plates of main frame, and extending over the entire length of the 
tracks, thereby preventing accidents to the personnel during travel- 
big, and may be conveniently used for mounting of the sight, tool 
and spare part chests, etc., when deemed necessary. 

This self-propelled caterpillar type unit has successfully demon- 
strated its advantages, for, due to its mobility, it may readily be 
transported from place to place under unfavorable ground and 
weather conditions and is able to open fire immediately upon its 
arrival in a position. The advantage of this type of machine having 
artillery mounted directly on a vehicle with caterpillar treads for 
military purposes lies in its ability, due to very low unit ground 
pressure, to negotiate soft and uneven surfaces, imposible to the 
usual type of power vehicle, except under the most extreme diffi- 
culties. 

Anti-aircraft guns are receiving careful attention with the view 
of further development of easily maneuvered and quickly handled 
pieces. They are mounted on self-propelled vehicles, as trucks or 
caterpillars, or on some easily drawn vehicle such as an auto trailer. 
They must of course be designed for all around and high angle fire. 
Used as they are against swiftly moving aircraft, special guns of 
high velocity and sights specially adapted to this work must be 
considered. 

Several changes are apparent in the trend of design for new field- 
pieces of the wheeled type. 

The desirability of wider traverse and higher angles of elevation 
has led to the development of the split trail carriage for both guns 



and howitzers. Many of the newer guns permit of as high elevation 
as that of the howitzers. 

Another development is that of interchangeable guns and howitzers 
for the same carriage. For example, one type of carriage being de- 
veloped is that for mounting a 75 millimeter gun or a 105 millimeter 
howitzer. 

The hydro-spring type of recoil mechanism seems to be almost 
entirely superseded in the latest designs by the hydropneumatic 
recoil mechanism. 

The tendency in latest practice is to relieve the carriage from road 
shocks as much as possible by the use of spring suspension and 
rubber- tired wheels. 

The desirability of small light fieldpieces which can be taken to 
the front by the infantry has led to the infantry accompanying gun 
and howitzer. Some of the latest experimental guns of this type are 
2. 24-inch pieces so light that they are easily moved by man power. 

In general, it will be seen from the above that future artillery 
will more nearly approach the ideal, to the degree that the principles 
of high power and swift transportation are incorporated in the design. 

o 

18322820 25 



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