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Full text of "SAWMILL WITHOUT SAW-GATE - United States Patent 700"

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Specification of letters Patent No. 700, dated April 21, 1838.

To all whom it may concern:

Be it known that I, John C. Yates, of Columbia, in the county of 
Maury and State of Tennessee, have invented a new and useful 
Improvement in the Construction of Sawmills, called "Yates' 
Gateless Sawmill," which is described as follows, reference being 
had to the annexed drawings of the same, making part of this 

The frame A, Figure 1, may be made of any convenient form, size, 
and strength for the purpose intended. A vibrating beam B, Figs. 
1 and 2, is placed at the top of the frame. Its fulcrum C, is 
triangular or polygonal, instead of round. It moves in 
rectangular boxes D, instead of curved. The sides of the fulcrum 
moving on the bottoms of the boxes may be made convex to prevent 
jarring, as the beam vibrates. To each end of the vibrating beam 
is attached a straight saw E, E, in the following manner, whose 
lower ends are attached to a crank shaft F, below. As the saws T 
heads, rods, &c., at both ends of the vibrating beam are the 
same, only those at one end need be described. Then, to the end 
of the beam is attached in the usual manner by a joint a 
connecting rod G: to the lower end of this connecting rod a T 
head H: to the T head a harp-iron I with nuts J to raise or lower 
it: to the harp iron the upper end of the saw E, the lower end of 
said saw being attached to another harp iron, or it may be 
attached immediately to a lower T head K, the last 35 mentioned T 
head K being connected with the crank shaft by a pitman rod L.

The saw E is made to work vertically by means of rods M passing 
through the T heads over which rods they work loosely, said rods 
being sustained in a vertical position by arms K projecting 
horizontally from the main frame or in any convenient manner.

The nuts J on the ends of the harp iron are for straining the 
saws when they require it.

The other connecting rod, upper T head, harp iron, saw, lower T J 
head, pitman, rod, &c., attached to the other end of the 
vibrating beam being made similar to those just described need 
not, therefore, be more particularly described.

The crank shaft may be turned by pulleys and bands; or cog 
wheels, by steam; or by water by means of a flutter wheel, or 
otherwise, applying the power directly to the crank shaft, or by 
the power of steam applied directly to the crank shaft.

There may be more than two saws, and the saws may be arranged in 
gangs, or otherwise.

The operation of the machine is as follows: The crank shaft F 
being put in motion, one of the cranks will be up while the other 
is down, the pitman rod, saw, and connecting rod on one side 
draws down one end of the beam, at the same time raising the 
other end with the opposite saw, the beam vibrating on the 
triangular fulcrum. When one end of the beam is down it of course 
will rest on the corners of the fulcrum nearest said depressed 
end of the beam, at the same time changing the center by raising 
it from the box and increasing the length of the other end of the 
beam, thus keeping the saws always strained to a proper degree of 
tension and so vice versa. The object of having the fulcrum made 
in this shape is not only to change the center of vibration 
alternately by which the arms of the beam are alternately 
lengthened thus compensating for a loss experienced at every half 
revolution of the crank shaft by the extension of the pitman rods 
but also to prevent the saws or works being broken for when the 
cranks are horizontal the pitman rods form the hypothenuses of 
two triangles, which of course will produce longer lines than the 
perpendiculars or the lines extending from the center of the 
joint or connection with the lower J head to the center of the 
crank shaft, and consequently produces a strain or drawing down 
at each end of the beam, simultaneously, and the plummer boxes 
being immovable and the center of the cylindrical fulcrum as of a 
steam engine for instance remaining unchanged. Of course the saws 
must either be broken or stretched, or some part of the 
connection be lengthened or injured. But the fulcrum being made 
of a triangular, or polygonal shape, with the lower side or that 
which moves over the bottom of the box flat, or nearly so, the 
center of the vibrating beam is made to descend or approach 
nearer to the crank shaft at the moment the pitman rods are 
extended when the beam and cranks are horizontal and thus the 
strain, before mentioned, is prevented. This constitutes the main 
feature of my invention.

The timber to be sawed is secured upon a carriage and brought to 
the saws and receded from them in any of the most improved modes 
in use, known to mechanics; but as no claim is made to this part 
of the machine a particular description is not deemed necessary.

What the subscriber claims as his invention and which he desires 
to secure by Letters Patent consists—

In the form of the fulcrum of the vibrating beam in combination 
with the rectangular boxes in which it moves.


Witnesses: Wm. P. Elliot, W. Bishop.