UNITED STATES PATENT OFFICE.
JNO. C. YATES, OF COLUMBIA, TENNESSEE. SAWMILL WITHOUT SAW-GATE.
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.
JOHN C. YATES.
Witnesses: Wm. P. Elliot, W. Bishop.