HISTORY AND METHODS
BALTIMORE AND OHIO RAILROAD
KARL F. BALDWIN, Jr.
For Admission to the
National Engineering Honorary Fraternity
TAU BETA PI
BETA CHAPTER OF MARYLAND
University of Maryland
College Park, Md.
After a description of "air conditioning," a historical
sketch is given outlining the developments in air conditioning
on the Baltimore and Ohio Railroad from the first experiment in
that line in 1884 to the present day. The early developments
mentioned include the ice system tried in 1906 and the air
washing system tried on (loach 225 in 192b. The later develop-
ments include the chilled spray system on couch 5275, the first
completely air conditioned car in the world; and the Colonial
Diner, "Martha Washington," the first B. & 0. c^r to be equipped
with a mechanical refrigeration air conditioning system. A
few of the first completely air conditioned trains are mentioned
as well as some l^ter developments.
There is n^xt a discussion of the air conditioning
systems tried by the B. & 0., and an explanation in detail of
the mechanical system. The methods used on coach 5275 and on
the "Martha Washington'/; are described in detail due to their
historic interest. A discussion of the developments since
then follows, including the gasoline power plant, the discov-
ery of Preon, the development of the high capacity storage
battery and the third brush generator. A few of the more
recent experiments are mentioned, including those of heating.
There follows then a discussion of the costs of
operating the units, and a summary of the benefits derived In
the line of increased comfort.
Finally, there is a very complete bibliography of
magazine articles on the subject to date.
- FORWARD -
It is extremely appropriate that at this
time a report be made of the air conditioning of
passenger cars on the Baltimore and Ohio Railroad.
Appropriate because air conditioning has been the
one development that has made the greatest progress
during the years from 1929 to the present. It is
an advancement that is having a great effect on
lifting what has been called the greatest depres-
sion that the United States has ever had.
Except in a few isolated cases of theaters
and special industrial processes, the growth of
air conditioning began during 19^9 and 1930. The
railroads have perhaps more to gain from air condi-
tioning than almost any other Industry. As in
practically every railroad development In this
country, the Baltimore and Ohio has been a pioneer
in this modern evolution.
I. AIR CONDITIONING OF PASSENGER CARS
Ever since the first passenger carriage for a horse-
drawn railroad car was built, there has been the problem of
proper ventilation and comfort for the passengers. ftith the
development of the steam engine the problem became more accute,
as to have the windows open meant the admittance of smoke and
For a very long time the problem of properly cooling
a passenger car has been studied. The relative small capacity
of the car, the crowded conditions, and the fact that a railway
car is a poor insulator of heat, all contribute to making a car
extremely uncomfortable in hot weather, especially if an attempt
is made to keep the dirt out.
There have been many definitions of air conditioning.
The definition used in this thesis is "Cooling for comfort."
The earliest records available at the Patent Office
show that the first attempt of air cooling of cars occurred
fifty years ago last summer, in 1884. This system was developed
by a Dr. Keys and was installed in a B, & 0. car at the Mt. Clare
Shop. It consisted of a huge ice h> x in the bow of the car,
equipped with air ducts which would force air over the ice from
the breeze caused by the train's motion. This was only slightly
successful because of poor circulation of air in the car and ex-
cessive use of the ice.
In 1906 another ice system invented and patented by
J. C. Witter was installed in a B, & 0. dining car. An ice box
was placed in the upper deck of the car, between the dining room
and the end finish. This box was in two sections with about 18
inches between the sections. An ordinary electric fan was placed
In this space. The ice compartments contained several longitudi-
nal flutes, or tubes, these being surrounded by ice. These
flutes were for the purpose of giving the air a positive contact
with a cooling surface as the air was drawn through these tubes
by the fan. One set of flutes was on the intake side and the
other on the side through which the air was discharged into the
room. A trap door on the roof was the means of replenishing the
This carj No, 1008, was used on a trip in 1906 from
Chicago to Philadelphia, and carried representatives of the rail-
way Supply Men's Association and members of the Master Mechanics
Asaociatlori and Master Car Builders Association. From a cool-
ing standpoint it operated very, satisfactorily, but the too
frequent stops necessary for ice, and the consequent cost of
operation, rendered it Impracticle.
It should be noted that the difficulties were mainly
due to the small siz^s and poor Insulation of the ice box«s«
This system is the forerunner of ice systems used today by some
In 1925, Coach No, 225 was equipped with an air wash-
ing and conditioning system in the Mt. Clare Shop. The air was
washed and cooled by being drawn through a system of chilled
sprays, and then was distributed into the car through a system
of air ducts. The system was satisfactory, but its use was not
extended because the pumps and fans used more electrical current
than could be furnidaed by any car generator in existence at that
Meanwhile the railroads had lost a great deal of pas-
senger traffic due to new competition from automobiles, buses,
and the beginning of airplane travel. It was decided that to
regain passenger traffic it would be necessary to make train
travel more inviting. The primary requesite for this was "the
elimination of dust, cinders, and smoke. The B. & 0. mechani-
cal experts were not slow at deciding that the only way to do
this was to keep the windows and doors closed tightly while the
train was moving. Of course this meant that some means must be
supplied of famishing and controlling a supply of clean and
fresh air. Experiments soon showed that it would be easy to
cool and dehumldify this air at the same time that it was me-
In 1929, experiments were made by the B. & 0. which
showed that cooling modern passenger cars was possible. In
July, Coach 5275 was furnished for complete summer air condi-
tioning and exhausting tests made both standing and running,
and these tests showed that a mechanical air conditioning system
was practical for railway cars.
In 1930 more tests were made and equipment was instal- -
led in the Colonial Diner, Martha Washington. This car was ex-
hibited at the 1930 A.R.A. Convention at Atlantic City in June.
In 1931 this equipment was replaced by the standard equipment
which is now In use, with several changes, of course. The
methods used on these cars will be described in detail later.
These and other experiments in 1930 were so satis-
factory that in 1931, the B. & 0. installed 38 units. On May
24, 1931, the first completely air conditioned train in history,
"The Columbian," was put in service between New York and Wash-
ington, one trip each way each day. These standard units were
built by the York Ice Macninery Co., of Yor±c, Pennsylvania, and
installed by the Railroad Gompany's forces in the Mt. Clare shops
During 1932, a total of 122 cars on the B. & 0. and 16
on the Alton Railroad were completed. On April 20, 1932, the
"National Limited," the first long distance, fully air condition-
ed, sleeping car train was inaugurated. This operated daily in
Figs. 4 and 5
The Martha Washington, the. First Completely Air Conditioned Car Operatep in Regular Railway
Service— April, 1930. Showing Air Intake for Cooling Tower at Far End
and Overhead Air Distribution Duct
The "Capitol Limited" of the Baltimore & Ohio Was the First Long-Distance Train to Be Fully Air-Conditioned
both directions between New York, Cincinnati, Louisville and
St. Louis. The "Capitol Limited," similarly equipped began
operations between New York and Chicago on May 22.
In June of that year, theB. & 0. furnished complete
equipment for two trains which were to carry the Inter-Collegi-
ate Athletes from Jersey City to Los Angeles for the Olympic
Games, and there were three air conditioned cars on each of
these trains, two diners and a lounge. None of these six cars
showed any trouble on the trip or return.
In November, 1932, president Hoover's train in his
trip to California was furnished with two B. & 0. Air condi-
tioned cars, a sleeper and a lounge. There was no trouble here
The Capitol Limited was put on display outside the
Travel and Transport Building at the Century of Progress Exposi-
tion, both in 1933 and 1934. The locomotive was No. 5510, named
"Lord Baltimore." All six cars were completely air conditioned.
Following the locomotive they were: first, a standard indivi-
dual seat coach; second, a reclining seat coach, used for night
service, and the first coach of that kind ever air conditioned.
The third ear was a colonial diner, "Mary FicKeragill. " The
fourth car was a typical lounge car in daily service on the B, &
0. The fifth car v/as an up-to-date sleeper, named the "Illinois."
The final car was a sun-room observation car of the latest style
and named the "Maryland. "
In 1933, the B. & 0, had 162 air conditioned cars in
use, and by the end of 1934 this number will be very much higher.
TYPES OP AIR CONDITIONING SYSTEMS
Modern air conditioning of passenger cars was not a
spontaneous thought quickly developed into reality. The B. & 0,
gave considerable thought to it for several years and made many
plans and experiments before an actual installation was made.
Consideration had to be made for the various possibilities. For
instance, consideration was given to having the cooling aparatus
at the front of the train. This was decided unfeasible because
of lack of flexibility and the fact that unequipped cars could
not be used on the train. Also the apparatus would have to be
so designed to take care of a very great overload to care for
extra cars. For these reasons it was decided that it would be
best to have an individual unit on each car.
Three methods of cooling the air was next recognized:
Ice system, steam ejector system, and mechanical compression
system. All these systems are now in use on different roads.
All the ice systems are basically alike. Generally
there Is an ice storage compartment of large size; and an air
cooling unit usually In the upper deck of the car, with a suit-
able fan for circulating the air. In some eases closed coils of
cold water cool the air, while in others a cold spray is used.
Of course, pumps are also necessary for circulating the water.
The rate of ice meltage can be determined by consid-
ering the temperature and atmospheric conditions within the car.
Experiments imde by the B. & 0. showed that the Ice consumption
for a standard car would vary between 385 and 500 pounds per
hour, and with ice at $.25 per hundred or $5,00 per ton, the
cost of operation was from $.97 to $1.25 per hour. The natural
conclusion was that while it mght be a suitable system for short
runs, on through trains it would be rather expensive, even though
the initial cost is small.
The steam ejector system depends upon the fact that
water will boil at low temperatures if the pressure is reduced.
The refrigerant used is water and the refrigerating power comes
from steam from the locomotive. Experiments 3howed that the
system required £05 pounds of steam per hour per car at 50
pounds of pressure for operating the ejector, plus a line loss
of 35 pounds per car, or a total of 240 pounds of steam per hour
per car. The additional load on the locomotive is about lC|r
horse-power. The pressure drop along the line would limit the
number of cars that could be served by this system, and also
steam would haie to be provided from another source when the car
is in a station or yard without the locomotive connected.
The system hadmany good points, but it was decided
that the mechanical compression system would be better. In this
system, a mechanical compressor takes the place of the steam in
the steam ejector system.
The following are considerations to be met in the re-
1, Low initial investment.
2, Long life.
3, Low operating cost.
4. Low maintenance cost.
5. Low supervision cost,
6. Low obsolescence.
7. Expensive additions to yard and terminals
must not be necessary.
8. Flexibility of operation.
9. Light weight.
10. Small space.
14. Capacity must be great enough' to keep the
car at a comfortable temperature.
Before taking up the study of specific equipment, it
would be well to consider the general theory back of mechanical
AIR CONDITIONING CYCLE
Air is taken from the body of the car and mixed with
filtered outside air and then passed through the air conditioner,
(Pig. 13). The air is cooled in the air conditioning unit, and
moisture will condense out due to the fact that air at a lower
temperature will hold ]b ss water than at a higher temperature.
This cooled and dehumidified air then passes into a duct along
one sld» of the roof, or through the center top section, of the
entire length of the car.
The air leaves the outlet grilles with ju3t sufficient
velocity to carry the width of the upper deck of the car. Cool
air has greater density than warm air and so it decends evenly
over the whole passenger area, mixing with the air that is al-
ready there and providing draft-free ventilation and cooling.
The ventilators along one side of the car are available in case
of an emergency.
This discussion of the refrigerating cycle will con-
sider the refrigerant FREON "because that is used today exclu-
sively. The previous application ofammonla will be later dis-
Figure 14 shows a representation of this cycle and the
characteristic P-H diagram. The whole principle lies in the re-
frigerant picking up heat at one pressure and temperature level
and giving up the heat at a higher temperature and pressure level,
Every liquid has a definite temper ature--pres sure relation.
The refrigerating system consists primarily of a com-
pressor, a condenser, a regulating valve, and an evaporator.
Following the diagram, Figure 14, FREON liquid at 120 pounds
and 102° is allowed to pass the regulating valve. The pressure
will here he much reduced, to say 30 pounds, and the FREON will
assume a temperature of 32°. The refrigerant will boil due to
the heat from the air around the evaporator. This vapor will be
taken by the compressor and re compressed to 120 pounds and then
discharged into the condenser. Here water of say 80° tempera-
ture passes over the condenser and takes up heat from the com-
pressed gas and condenses it into a liquid. Thus the heat is
removed by the water and the refrigerant is only a transfer agent.
It picks up heat at a low temperature level from the air and dis-
charges it to the condensing water at a higher level.
Figure 15 shows just such a system diagrammatically,
and is the type used on most modern passenger cars. All the es-
sential components may be seen: compressor, condenser-cooling
tower, float regulator and evaporator in the air conditioner unit.
The condenser cooling tower had to be novelly designs d because
it is impossible to carry a sufficient supply of later on the
car for the condensing purpose. This cooling tower takes the
condensing water and sprays it to the open air over the coil,
where by evaporation of a little of the water, it cools and con-
denses the compressed gas. The air is supplied by being contin-
uously pulled through the tower by a fan. Thus the transfer of
heat is from the air passing through the air conditioning unit
(«R CONDITIONING UNIT
P _V -
to the refrigerant, from the refrigerant to the condenser water,
and from the condenser water to the outside air. Some of the
water lost from the cooling tower by evaporation is replenished
by an ingenious method of using the water that is dehumidified
from the air in the air conditioner. The level of water is
automatically maintained from a reservoir through a v^lve.
Another type of condensing medium is used in some cases, air
being used without any water sprays, (Fig. 16)
AIR CONDITIONING UNIT
, CON DENSER
A very large volume of air is drawn across the condenser coils
by more than one fan, and the condensation takes place without
the use of water.
The theory above explained has been the same for all
mechanical air conditioning systems. The major developments
have been in the design of the power supply and in the refriger-
ant gas used. These will be taken up in chronological order.
The first two cars ever to be completely air condi-
tioned will be described in detail, due to the historic Interest.
THE FIRST COMPLETELY AIR CONDITIONED CAR
The B. & 0. Coach No. 5275, was the first railway
passenger car in the world (July, 1929) to be equipped for com-
plete air conditioning, i.e., freeing the air from all dust,
soot, cinders and other foreign material and controlling its tem-
perature and humidity. (Fig. 1. page 7)
Except for the evaporators, commercially available
equipment was used. Two water spray units were placed in the
car, one at each diagonal corner, a seat being removed from each
olace to accomodate the unit. A belt drive motor driven compres-
sor was Installed In one of the saloons and two anmonia condensing
tanks were located near the roof of another saloon. Two evapo-
rators and two water circulating pumps were located beneath the
car floor. Five single phase 60 cycle 220 volt A-C motors were
used. The 7^ ton ammonia compressor required a 7^ horse-power
motor. The two centrifugal pumps were driven by a f horse-power
motor and the two water spray units each by a 1 horse-power
\ch 5275 — Showing Air Distribution Duct
O O (T
> J " "* — *2
^'n ^ m ^ *«■* ^ ^ ^ ' fi F^
motor. Each of these units handled 27 gallons of v.ater per
minute against about 40 pounds gauge pressure and delivered
about 2500 cubic feet of air per minute against a pressure of
about .6 inch WO.
All car windows were double sashed and the ventila-
tors closed. Fresh air and re-circulated air was passed through
the chilled water spray where dust and foreign matter was removed.
Air at the desired temperature and humidity was then distributed
without drafts through insulated air ducts attached to the half
deck of the car.
The spray water was recooled and re-used. Ammonia was
the refrigerant used in the compressor as previously described.
The condenser cooling water was passed through the other air con-
ditioning unit where outside air was drawn through the warm water
spray, cooling the condenser water bacx to approximately the tem-
perature of the outside air. In this way the condenser water
was available for re-use. About 12 gallons of water per hour
were lost under the worst conditions and was automatically re-
placed from the water supply system on the car. An automatic
electrically operated thermal device cotrolled the motor driven
compressor in accordance with predetermined setting for the de-
sired car temperature.
After a series of standing and road tests covering
about two months, the test equipment was removed and the car re-
stored to its original condition as the air conditioning equip-
ment was not suitable for permanent use and the power supply
Figures 1 and 2 show pictures of this car, and a dla-
gram of its equipment is shown in Figure 3.
This preliminary experiment shows that there were two
obstacles still to be overcome before air conditioning could be
commercially attained in railway cars. What was needed was a
suitable power supply, and a compressing unit of proper capacity
and design to be placed underneath the car. Ammonia was con-
sidered the only applicable refrigerant and it was recognized
that no chances should be taken for allowing any ammonia gas
from leaking into the car, A special 7^ ton, smaller, lighter
compressor was designed that could be mounted below the floor,
(7^ ton means capacity equivalent to cooling by 7^ tons of ice).
For the supply problem, a gear driven 10 Kilowatt 110 volt-D-G
generator was developed. The gear drive was constructed with a
ratio of 2.43 to 1. With 36 inch car wheels, the generator gave
it full output at about 31 miles per hour, declining with declin-
ing speed to 85 volts at about £8 miles per hour,
The next car to be completely conditioned was the
colonial dining car, the Martha Washington (No. 1036). Pictures
of this car are shown in Figures ,, Q t 10, 11, and- lid.
The function of the air conditioning equipment can be
followed by consulting Figure t3. The mechanical air filters
were sheet steel housings containing steel wool, as shown at (a)
along the roof line near the pantry. The alrwaa cleaned of
cinders, dust, and other foreign matter here. The air then
passed over the cooling coils (b) which were 51 1-inch aerofin
pipes each 3 feet long, and giving a cooling surface of about
600 square feet. The air was then blown by two fans (c) driven
by one |- horse-power 110 volt motor operating at 1,000 RPM, each
fan delivering about 1200 cubic feet of air per minute against a
static pressure of .6 inch WG. The air was distributed through
the insulated ducts (d) on the roof. It was delivered to the
interior of the car through the louver ed openings in the half
deck. Adjustable perforated openings were provided to prevent
drafts and to give equal distribution of air.
When the temperature inside the car reached a certain
temperature below the outside temperature, the temperature regu-
lator (f ) controfcd the air recirculating intake (e) to prevent
further cooling. A mechanical interlock with the regulator (f),
the louvers of intake (e)were closed and the louvers of (e 1 ) were
opened to permit recirculation of air without passing over the
cooling coils (b). The regulator (f) reversed the process when
the temperature rose to a predetermined point. The regulation
worked on a difference of about 3 to 5 degrees P],
In the refrigeration cycle, after compression, the
hot ammonia gas was delivered to condenser (m). In this tank
were coils of Dioe containing water. The condenser liquid
ammoniawas then parsed to the expansion valve (p) from where it
wentto the evaporator (I). In this evaporatorwere pipe coils
through which water circuit ted to the cooling air conditioning
unit. The ammonia gas was returned to the suction side of the
Lquvered Outlets in Half Deck fob Air Delivery
AiTi.i Blossom Fssrn \i.. Winchester, Va. — Baltimore and Ohio Colonial Dining Car,
corapressor (n) through the back pressure valve (r). The ammonia
discharge pressure was 160 to 170 pounds, and the suction pres-
sure 55 to 60 pounds. The compressor is pictured in Fig. 10.
Return to the condenser (m) , Thecondensing of the
ammonia imparted heat to the water. The motor driven pump (1)
circulated this water to the cooling tower (k), The water ttas
cooled here by a spray at a rate of about 27 gallons of water
per minute at a pressure of 40 pounds per square inch, and out-
side air was drawn into the water spray by means of a fan mounted
on the same shaft with the spray pump. Some condenser water Was
lost by evaporation and was re supplied by the water tank (j)
located overhead, and through an automatic float control valve
at the tower (k). Under worst conditions, a loss of 10 to 12
gallons of water per hour were experienced.
Now reconsider the evaporator (i). Due to the expan-
sion of the ammonia through this tank the temperature of the
water in the pipe coils of the tank Was reduced and the pump (h)
delivered the chilled water from the evaporator (i) to the cooling
coils (b), and thence around again to complete the cycle.
The thermal control (o) prevented the temperature of the
evaporator from going so low that the water in the cooling coils
would freeze. This valve controledthe back pressure valve (r).
As the compressor continued to run, local circulation continued
through the by-pass valve as -:hown on the compressor (n). If for
some reason the pressure on the discharge side w :>uld rise be-
yond a certain point, a safety switch disconnected the motor
through a relay.
W. 110 Volt Direct Current Gear Driven Axle.
Generator. Car 1036
Motor Driven Refrigerating Compressor, Log
Beneath the Floor of Car 1036
^t Over i
ekiiead Bronze Grills Concealing the Autom
au.v Controlled Air Recirculating Dampers.
1'a.ntky End, Car 1036
Power was supplied by a 10 K.W. 110 volt direct
current gear driven generator (Fig. 9), operating above a
critical speed of 28 miles per hour with a gear ratio of 2.73
to 1. Provision was made for receiving power from a wayside
connection when the car was standing at stations or in yards.
The fan (c) and the cold water pump (h) were later
changed to operate from the regular car lighting batteries at
32 volts, direct current, and the 4 kilowatt belt driven axle
generator was replaced with a 5 kilowatt gear driven generator.
This enabled the circulation of air and cold water when the
car was standing still or moving slower than 28 miles per hour.
When the car speed reached 28 miles per hour, an
automatic switch closed on the 110 volt generator. The various
motors were automatically started through automatic controls
until the car speed declined below the critical speed. A volt-
age regulator kept the voltage below 115 volts at higher speeds.
Figure 8 shows the electrical diagram of the control.
The compressor motor will start first, followed by the condenser
motor pump and the cooling tower fan motor. Automatic protec-
tion was provided so that if any of the auxiliary motors failed to
start the compressor was discontinued, and a light signal was given
the steward of the car.
The cold water pump and motor driven fans were subject
to manual control. The control circuit was so interlocked that
the compressor and its auxiliaries could not be operated" unless the
fans and cold water pump were running.
This equipment was removed the next season (1931) due
to the fact that it was too dependent upon the speed of the
train. Experiments were made with bulky electric storage bat-
teries. Another scheme considered was a "central system" with
the mechanical e uipment installed in a forward coach. These
developments showed a need for an independent reliable source
of power. Several means were considered* a small steam engine
in each car, Diesel engine and finally gasoline engine drive.
In the subsequent season two types of gasoline installations
were made. In one, the gasoline engine drove a generator, and
In the other It drove the compressor and the pumps directly
from a counter-shaft, (See Pigs, IV, IS page 2b) Also, brine
was substituted for water In the cooling unit. These systems
operated successfully the whole season.
During the summer of 1931, the Kinetic Chemical Co.,
Inc., a subsidiary of E. I. Dupont de Nemours announced the
developement of a new gas which was very superior to ammonia as
a refrigerant. This gas is dichloro-dif luro-methane, known as
Preon or F-l£. This gas is colorless, odorless, non-corrosive,
non-combustible, and non-inf lamable, as well as non-toxic in
relation to health. This meant that it was now possible to ex-
pand the refrigerant directly into the cooling unit usually
located in the upper deck of the cars, and to eliminate the neces-
sity of the brine- cooling tank under the car, and the pump for
circulating the brine. It was now able to increase the cooling
capacity fifty per cent and at the same time reduce the power
aasoline engine driving compressor and
pumps through counter-shaft.
Gasoline engine driven generator. 10 k.w.
B Schematic diagram of the York Air Conditioning System for passenger ears. This diagram illustrates
not only the closed refrigerating cycle but also the secondary liquid rirruit and the cooling tcater circuit
SUCTION— *-[ri LIQUID—*f!
■'■ 'V//7////////////X y//////////////y
' ' V////?////////Av///////////////// //
• V? COOLING LIQUID
-7 -la OVERALL OF INSULATION
" OIL DRAIN
COOLING LIQUID IN
The Mquid Cooling L'nit is employed for cooling the secondary liquid which is circulated through
the air conditioning unit. The unit is York heavy duty shell and tube construction, oj the multi-pass
type. Dimensional drawing of Liquid Cooling I nil ia also included.
needed. It also made it possible to reduce the time necessary
for pre-cooling the car previous to dispatchment of the train.
It had previously been necessary to turn off the compressor
when in tunnels due to the possibility of the ammonia fumes get-
ting in the car. This was no longer necessary. This discovery
has helped greatly In solving the problems confronting the air
conditioning of passenger cars.
About the same time, the Exide Storage Battery Co.
announced the development of a high capacity storage battery
which would take no more room than the old car lighting battery.
This suggested that a generator might be developed that could be
used with these batteries to supply all the needed power. The
gas engine -driven power plant was a source of more or less un-
necessary maintainance cost. This operated at 2200 RPM with
full throttle for an average of 18 hours a day. The service
obtained was remarkable, but the attention required to keep the
unit going was troublesome.
The elimination of the gas engine and the development
of a generator to be used with the new batteries was solved by
the development of a 7§ KW third brush type generator, driven by
a special sturdy combination belt and gear drive from the car
axle. (Fig, 21, 22) The maximum power requirement is from 150
to 160 amperes at 34 volts at condensing pressures from 120 to
135 pounds .
The third brush generator provides 235 amperes at 3o
volts for a speed of 35 miles per hour, and 175 amperes at 35
volts at 75 miles per hour. At all times above about 20 miles
«* -w »..--»»-»---'-»----»»-»-- , » , '-'- w
Axle Generator Which Supplies the Power for the Operation of the Air Conditioning Equipment
Belt pullies and gear box.
oer hour the generator furnishes sufficient current for operat-
ing the cooling system and for keeping the batteries charged.
The output is good at as low speeds as 20 MPH, and is regulated
solely by the position of the third brushes, no other regulator
The design of the compressor was changed slightly for
use with the Preon, and a description is herewith given of the
compressor which has been used since that time. It is a two
cylinder 4" diam. by 3" stroke, single acting type, driven by a
belt from a 5 H.P, direct current 36 volt motor, and operates
at 400 to 425 RPM. This unit is mounted under the car in a small
cabinet with removable sides, (Fig, 23). The tappet type valves
of the earlier compressors were replaced by diaphragm type,
located in the pistons. Splash lubrication is used with the oil
reservoir in the crank case. These compressors have given good
service for three seasons.
It i^ necessary to drain water from the cooling towers
at the beginning of freezing weather. Since 1933, the condens-
ers installed have been of the air cooled type, eliminating the
water feature and permitting the system to operate in any season.
Another feature of the air cooled condenser i3 that it may be
mounted under the car, whereas the old water cooled condensers
were mounted vertically in some space in the car. In most cases
it was mounted on one side of the vestibule in what otherwise
would be an entrance doorway. This was no disadvantage in diners
or combination coaches, but in regular cars it eliminated one
door In each car.
Motor-Driven Compressor Designed For the Freon IF-12)
Refrigerant — The High- and Low-Pressure Cutouts F
Starting and Stopping the Motor Are Shown
Between the Motor and Compressor
- i2) M
AIR CONDITIONING UNIT
The Electrical Control Panels permit the operation of the entire
equipment from button control. The "stop," "start" and "run"
push buttons, easily accessible in the control cabinet, make the
starting and control of the equipment as easy as turning on and
off the lights in the car. A selector switch is also provided in order
that air conditioning and fan equipment may be operated without
refrigeration for Spring and Fall weather conditions.
Here, again, York has simplified the control mechanism as
much as possible and all portions of the system are so interlocked
as to incorporate every possible safety feature.
I If left, the York Con-
densing Cooling Tower unit
consists of a water spray
rhantber flesignetl tit fit the
spa re available on the pia t -
form or within the ho fly of
tl i in ensional
Tower unit ,
2 : |-
f our teen
In 1935, there was developed a 7^ K.W. capacity volt-
age control generator similar to the standard car lighting
generator. It uses the same drive as before and furnishes suf-
ficient current to operate the air conditioning equipment. How-
ever it requires a voltage regulator which is not needed with
the third "brush generator. Both types are now being used.
At the beginning of the 1934 season, the B. & 0. had
accumulated over 31,000,000 car miles with their 149 air condi-
tioned cars, and the Alton over 1,070,000 miles with their 16
cars. There was a total of 38 failures in which case it became
necessary to raise windows and open ventilators. This makes
247,522 miles per failure on the B. & 0. The Alton didn't have
a single failure.
During 1934 only minor changes are being made in the
installation. They are mainly a center duct installation with
the air conditioning unit at the end of the car in the clerestory,
and the return air grille tubing units are in the fal^e ceiling
under the unit. The fresh air is obtained from the vestibule of
The electric control panel and the cooling tower are
pictured on pages 31 and 32 • The come let e plan of the air condi-
tioning equipment is shown in Figure 25 page 33.
Experiments have been made in an attempt to heat
through the same air conditioning system, using steam heating
coils in the air conditioner. To date very little actual service
has been gotten from these units, and no definite conclusions can
be drawn regarding their practicability. Tests on the B. & 0.
show that it is difficult to make the thermostats operate
properly in these units, and difficulty was also experienced in
that heat tends to rise anyway, and so heat added to the top of
the car tended to remain there and cause the floor to be cold.
During the last year, the B. & 0. engineers developed
a heating thermostatically controlled steam heater unit, and a
humidistat which automatically controls the humidity to be added
to the controlled admisture of inside and fresh outside air.
This system has proven that a car can be so heated to provide
maximum comfort for passengers during the winter just as the
cooling system provides maximum comfort during the summer. The
car provided with an air conditioning system in conjunction with
the new heating system should provide satisfactory service the
year around, especially on trunk lines that are subject to ex-
treme temperature changes during a single trip. The apparatus
should be so arranged that in the spring and fall, both systems
would operate automatically and not depend upon a car attendant
to control the car temperatures. More experimenting will be
done along this line, and this will probably be the next develop-
ment in railroad transportation after speedier service has been
Contrary to the general belief the cost of air condi-
tioning a passenger car is not excessive. The table below shows
how small an increase in passengers per car will completely pay
all fixed and operating costs for the equipment. The value to
the railroads may be realized by considering that every railroad
in the country that has put in air conditioning has reported an
increase in passenger traffic since doing so.
NUMBER OF PASSENGERS PER CAR PiR RUN REQUIRED
TO PAY ALL CHARGES
Increase in No. of Pas-
*Total Fixed Fare sengers Per Car Required
Length of and Operating Per to Equal Fixed and Oper-
R un Miles Costs Dally Run atlng Costs
■^Including interest and depreciation on investment.
These figures have been figured on an average cost per
car for the air conditioning equipment installed of $7,000.00.
Most installations will be less than this, but on some special
cars such as diners and business cars the cost will be higher.
The life of the equipment was conservatively chosen as 10 years,
although it should last longer. $50.00 per year has been in-
cluded for replacements, oil, additional refrigerant, etc. It
has been assumed that the operating period will be for 150 days.
The slight cost of the equipment can be seen from the above
table, and it Is obvious how alight an increase in traffic will
make the installation worth while. It can also be seen how the
length of run decreases the cost. It is reasonable to expect
at least two additional passengers a day on a hundred mile run,
or one additional passenger every two days on a five hundred
mile run. All additional traffic obtained above these will be
clear profit to the railroad company.
It m:ght be interesting to note at this time that
most of the first cars equipped with air conditioning were
diners. The effect on the railroad's revenue was opposite to
what was desired. It was found that people had a tendency to
linger over their food for a longer time, and usually conges-
tion occured and fewer people could be served. One or two
air cooled cars on a train did not materially increase traffic.
However, when whole trains were so equipped, it was extremely
apparent how business increased. On one railroad (The Ches-
apeake and Ohio), passenger traffic has increased 600 per cent
since installing air conditioning in their trains.
The purpose of the air conditioning system is, of course,
to provide comfort for the passengers. There have heeh set up
a definite standard for comfort conditions. These standards
take the form of so-called "Effective Temperatures." This is an
index of the degree of warmth or cold felt in response to temp-
erature, humidity, and air motion. These all have a, definite
relation to the ability of the body to rid itself of heat by
radiation, convection, and perspiration. All combinations of
temperature, humidity, and air motion which produce the same
bodily sensations are of the same effective temperature.
Besides the above relations, there is also a change
in optimum effective temperature, which takes place with changes
in outside air conditions. During summer operation of the air
conditioning system, there are different desirable inside condi-
tions corresponding to various outside c6nditions. The main-
tenance of a definite inside temperature throughout the summer
■ ould be equally absurd.
The following table shows outside temperature, inside
temperature recommended by A»S.H.V.E. and the inside temperature
actually found satisfactory in cars.
c ommenda t i ons
The above inside temperatures are higher due to the
fact that the car ran lower humidities. A.3.H.V.E. standards
are based on humidities of 50-60. ,
The chart below shows what temperatures are maintained
within the cars, and shows the 2 to 15 decree spread that has
been found most sstisfactory. A relative humidity between 40>
and 60$ will give comfort, but on the B. & 0. it is held within
a few percent of the 50$ mark.
^V 1 :
70 deq F
75 •■ -
73 - -
60 •• -
75 - -
hi ■■ -
77 - "
90 " ■•
7B - -
95 - -
BO - -
:oo ■ •
62 - ■■
105 " -
63 « -
fl^ •• -
US a •'
A spread from. M*2. to
15 degrees is the most
satisfactory, 6. 6 O.
o e * asj
It is well known how fine dust tends to creep into
even a tightly closed room. This is even lacking in the air
conditioned railroad car, due to the fact that the air in the
car is under a slight pressure as compared with outside air.
Hence, rather than dust coming in, it tends to be kept out.
It should also be noticed that due to the windows be-
ing kept closed, noise has been reduced 50% to 75>o.
The advantages of air conditioning may be summed up
as follows: The passengers are given a comfortable atmosphere
that is free from dust, cinders, and 3moke. The temperature and
humidity are nicely balanced and controlled. Here you have a
pleasant and healthful climate and a great reduction of noise
as an added attraction. All this has been accomplished without
a single increase in fares.
The Baltimore Engineer
Air Conditioning for Railway Passenger Cars,
J. H. Davis, Aug 1930, p 4.
Air Conditioning for Railway Passenger Cars,
A. B. Lawton, July 1934.
Baltimore & Ohio Magazine
B. & 0. Standard of Air-conditioning,
W. B. Whitsitt, June 1934,
Applications of Air Conditioning to Railroad Passenger Cars,
W. C, Goodman, and C. Kerr, Jr., Feb 1933, p 85.
Air Conditioning for Railway Passenger Cars,
A, H. Candee, Dec 1930, P 1037; same condensed;
Railway Mechanical Engineer, Feb 1930, p 1037,
Heating and Ventilating
Mechanical Cooling Features of First Air Conditioned Train
Aug 1931, p 5a.
Industrial and Engineering Chemistry
Air Conditioning for Rail.. ay Passenger Cars,
H. K. Williams, Jan 1933, p 13.
York All-Electric Air Conditioning System for Railroad Cars,
April 7, 1932, p 36.
Conditioned Air for Passenger Cars on B, & 0.,
Aug 9, 1930, p 267; also- Railway Mechanical Engineer,
Sept 1930, p 508.
Air Conditioned System for Passenger Trains,
R. W. Waterfill, Jan 24, 1931, p 233.
Three Air Conditioned Trains Operated by the B. & 0. ,
Oct 31, 1931, p 675.
B. & 0. Extends Use of Air Conditioning,
March 12, 1932, p 430.
Air Conditioning of Passenger Cars Established in Two Years,
Sept 17, 1932, p 390.
Air Conditioning? Old Stuff!
March 4, 1933.
Air Conditioning Operating Costs,
April 1, 1933.
Air Conditioning Requirements,
June 17, 1933, p 869.
Will Air Conditioning Attract More Passengers?
July 22, 1933, p 144.
The Air Conditioning Problem,
F, L. Sahlmann, Dec 30, 1933, p 913.
Cost of Maintaining York Air Conditioning Equipment,
Feb 24, 1934.
Air Conditioning of Passenger Cars,
June 9, 1934, p 836
Railway Carmen's Journal
Application of Air Conditioning to Railroad Passenger Cars,
Oct 1933, p 299; Nov 1933, p 331.
Air Conditioning of Trains, June 29, 1934.
Railway- Electrical Engineer
Air Conditioning Apparatus to be Applied to More
B. & 0. Cars, Nov 1931; April 1932, p 81.
Air Conditioning 78 Years Ago, April 1953, p 79.
One-Half Passenger per Car. April 1933.
A Different System for Every Car, July 1933, p 135.
Inventor Versus Maintainor, July 1933, p 138, 140.
Air Conditioning Requirements, July 1933, p 146,
Axle Generator Control, Oct 1933, p 215.
Air Conditioning Units, Jan 1934, p 17.
Air Conditioned Passenger Cars in Service in the
United States, Dec 31, 1933, Feb 1934, p 26.
What Price Air Conditioning?
L. J. Nerbarg, March 1934, p 45.
Factors Which Govern Choice of Air Conditioning Systems,
April 1934, p 67.
Air Conditioning Cost Factors, May 1934, p 96.
Railway Mechanical Engineer
How New is Air Conditioning? Dec 1933,
Air Conditioning la Established, Feb 1934.
What Price Air Conditioning? March 1934, p 75.
Air Conditioning System for Passenger Trains,
J. E. Boyack, Aug 1931, p 83,
Cooling Passenger Cars,
W. Herdlein, May 1933, p 240.
Passenger Car Cooling a Difficult Job, June 193b, p b09.
Origins of Air Conditioning,
D. L. Fiak, March 1954, p 122.
Comfort Cooling on Wheels, May 1934, p 233.
Air Conditioned Trains are now in Operation,
J, E. Boyack, Aug 1931, p 8.
System and Business Management
Pioneering Air Conditioning Brings B. & 0. Better Business,
D. Mllard t March 1934, p 114.
Air Cooled Trains on the B. & 0.,
R. M. Van 3aut, Nov 1931, p 26.
Hew System Air Conditioning, April 1932, p 23.
Western Railway Club Proceedings
Air Conditioning of Passenger Cars, March 1934, p 11.
Pamphlets of Exide Battery Company and York Ice Machinery
Some time was spent in Baltimore in an attempt to
get some information from the B, & 0, Railroad. The writer
went to several offices and to the Mt. Glare Shops, but was
unuble to get any first-hand information at all. He was told
everywhere that the information was not known in that office, or
that it could not be given out. He was also refused permission
to take any photograohs. Finally a reproduction of a m. gazine
article was obtained, but it contained no pictures.
The writer wishes to state hia appreciation to the
secretary of the Engineers Club of Baltimore for information ana
copies of the "Baltimore Engineer." ALmost all of the earlier
pictures were obtained from this source.
The writer also v.ishes to state his indebtedness to
Mr. J. 8. McGollam of the York Ice Machinery Corporation of
York, Pa., for his very helpful letter and the excellent ph^mph-
lets he sent.
Finally, recognition is made to Mr. Edmund Freeman,
Librarian of the Bureau of Railway Economics in the Transporta-
tion Building in Washington, This library is the most complete
in America on railroad matters and the magazine articles above
listed were read from the stock of this library.