Improvements in Loom Let-off Motions.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Loom Let-off Motions.
We, JOHN MARSHALL LINSCOTT, of Worcester, in the County of Worcester
and State of Massachusetts, United States of America, Mechanic, and SERVULE
ABRAHAM BENOIT, of Worcester, aforesaid, Trader, do hereby declare the nature
of our invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
Our invention relates to that portion of the loom known as the let-off mechanism,
by which the amount of warp delivered from the warp-beam, during the process of
weaving, is determined; and it has for its object to provide means by which the
amount of warp delivered at each beat, or swing, of the lay shall be accurate and
uniform and also to provide means by which the amount of warp so delivered can
be determined by the operator, as the character of the weaving may demand.
In the following description reference is made to the figures in the accompanying
drawings, which represent a loom embodying our invention and in which:
Figure 1 represents a side view of a loom containing a let-off mechanism
embodying our invention and showing its application to the warp beam of the
loom.
Figure 2 represents a portion of the frame-work A of the loom, with a bent
elastic blade attached thereto for holding the hand lever by which the actuating
pawls of the let-off mechanism are disengaged.
Figure 3 shows a portion of the frame-work of the loom and represents a front
view of the let-off mechanism.
Figure 4 is a top view of the let-off mechanism.
Figure 5 is a side view of a portion of the let-off mechanism and represents that
part, which is directly actuated by the warp upon the warp beam.
Figure 6 is a detached view of the sliding cam plate held in vertical ways and
capable of moving downward as the warp is withdrawn from the warp beam. The
cam plate being supported vertically by means of a plate, or blade, resting directly
upon the warp.
Figure 7 is a view in elevation of the modified ratchet mechanism in which a
flanged friction disk is substituted for the toothed ratchet wheel shown in Figure 1,
the disk and sliding collar being shown in central sectional view.
Figure 8 is a top view of the flanged friction disk and vibrating arm carrying
the friction pawls, the shaft being shown in section on line 8, 8, Figure 7, and
Figure 9 is a perpective view of one of the friction pawls.
In the several figures of the drawings we have employed like letters to indicate
like parts.
A denotes one of the loom sides, forming part of the frame work of the loom,
A', A³, denote the frame work which is attached to the loom side and by which the
let-off mechanism is supported. A' refers to that portion of the supporting
frame work attached to the upper edge of the loom side which contains a bearing
for the upper end of the vertical shaft C, and also supports that part of the let-off
mechanism which is controlled by the warp upon the warp beam and A' refers to a
bracket attached to the inner side of the lower portion of the loom side and
supporting the lower end of the vertical shaft C³.
B denotes the vibrating lay; C the warp beam carrying a worm gear C'engaged
by a worm C2, which is carried upon a vertical shaft C, journalled in the supporting
frame work A¹, A³.
A crown ratchet wheel C is attached to the vertical shaft C³, and C' is a collar
turning loosely upon the shaft C³ and carrying four radial arms C upon which are
pivoted pawls C7 engaging the ratchet wheel C.
A lever D' is pivoted upon the frame work at D, with its upper end bearing

page_text: against one of the radial arms C and having its lower end pivotally connected with
the lay B by means of a link D2, which is provided with a slot D³ inclosing a
stud D carried by the lay and so arranged that each forward beat of the lay will
carry the stud Di beyond the forward limit of the slot D³ and impart a rocking
motion to the lever D¹ upon its pivotal pin D. The rocking motion of the lever D
gives a short angular movement of the collar C' and through the pawls C7 and
ratchet wheel C₁ turning the shaft C³.
The rotation of the shaft C³ turns the warp beam C through the worm C³ and
worm gear C¹, causing a portion of the warp to be delivered, or unwound, from the
warp beam at each beat of the lay.
The motion of the collar C³, pawl C' and lever D' is reversed upon the backward
swing of the lay by means of a spiral spring E attached at one end to a fixed
arm E and at the opposite end to one of the radial arms C.
The link D2 is pivotally connected with the lever D', which is provided with a
slot D to allow an adjustment of the link D2 along the lever D', in order to vary
the angular motion of the lever.
The frame work A', in which the upper end of the shaft C³ is journalled is
provided with lugs F, F', holding the vertically sliding rod F2, to which is attached
a horizontal bar F³, said bar carrying at one end a blade F, which rests upon the
warp F wound upon the warp beam C. The opposite end of the bar F3 carries a
curved bar F attached at one end to the bar F³ and having its opposite end
extending beneath and supporting the cam plate F7, which slides in ways F³, F³, in
the frame work A¹.
The cam plate F is supported in the path of one of the radial arms C as the
motion of the collar C is reversed by the action of the spring E¹. When the
warp beam is filled with warp the blade F will be raised and the cam plate F' held
in its highest position so the radial arm C6, brought in contact therewith, will
strike against the lower end of the cam plate, limiting the reverse motion of the
collar and pawl C7; but as the warp is unwound from the warp beam the
blade and connected parts will descend by their own weight, allowing the cam
plate F to fall and receive the contact of the radial arm C6 at a point constantly
advancing upward upon the tapering edge F, thereby allowing the angular motion
of the pawl C to be gradually increased as the diameter of the warp decreases.
By the proper construction of the tapering edge of the cam plate F7 the
angular motion of the warp beam, as actuated by the let-off' mechanism, will be
gradually increased so as to accurately compensate for the decreasing diameter of
warp and cause a uniform amount of warp delivered from the warp beam at each
beat of the lay.
It has, however, been found in practice that it is desirable to vary the tapering
edge F³, to correspond with extreme variations in the number of picks in each inch
of the woven fabric; one conformation of the cam plate affording an accurate and
uniform delivery of the warp in a coarse fabric, and another and different
conformation of the cam plate being adapted to finer fabrics. We usually provide
with a let-off mechanism a series of two or more cam plates with their tapering
edges so shaped as to adapt the let-off mechanism to the entire range of coarse, or
fine, fabrics intended to be woven upon the loom the requisite shape of the edge F
in each cam having been ascertained by experiment and in order to allow the cam
plates to be readily shifted the cam plate is supported upon the curved bar F6, but
it is not attached thereto, allowing the cam plate to be lifted out of the ways F
and other plates having a different taper, or inclination, of the edge F° to be
inserted as the coarseness, or fineness, of the woven fabric may require.
Sliding upon the shaft C³, is a collar G having an annular groove G', which
receives a lever G³ pivoted at G to the frame work. The lever G2 is extended by
a rod G* forming a hand lever, which is held in position between the loom side A
and bent blade spring G³. The collar G is provided with a flange G extending
over the pawls C7 the rear ends of which are turned upwardly above the radial
arms Cº so as to be struck by the flange Gʻ as the collar G is moved down by the

page_text: angular movement of the hand lever G', thereby rocking the pawls C' upon the
arms C and disengaging them from the ratchet wheel C*.
A small hand wheel H is attached to the upper end of the shaft C³ provided
with a hub upon which is wound a friction cord, or strap, H' with its ends attached
to eye bolts H2 held in an arm H³, projecting upward from the lever G' so that
when the rod G is raised allowing the pawls C7 to engage the ratchet wheel C the
arm H³ will be moved back drawing the friction cord H' tightly upon the hub of
the hand wheel H and offering a frictional resistance to the rotation of the shaft C³;
but when the hand lever G is depressed, carrying the flange Go down upon the
pawls C' the arm H³ is carried forward causing the friction cord H' to be slackened
and the frictional resistance removed from the hub H₁, thereby releasing the
shaft C³ and permitting the warp beam to be turned by the hand wheel H.
In the let-off mechanism herein described, the vertical shaft C3 is actuated by a
ratchet wheel and four pawls, carried by the four radial arms C6, extending from
the collar C and the teeth of the ratchet wheel are so shaped that the distance
between the acting points of the pawls shall equal a certain number of teeth and a
fraction of a tooth so as to secure a finer graduation without reducing the size of
the teeth in the ratchet wheel, this form of ratchet mechanism is, however, adapted
to the coarsest varieties of fabric and for finer goods we employ a flanged disk in
place of the ratchet wheel C4 and a friction pawl engaging the same, the whole
constructed in accordance with any of the well known forms of friction feed.
In Figures 7, 8 and 9 we have shown one form of friction feed which can be
employed in place of the pawls C7 and toothed ratchet wheel C' as shown in
Figure 1. Jdenotes a wheel attached to the vertical shaft C3 and provided with a
friction flange J. The collar C is provided with two radially projecting bars, or
arms C upon the under side of which are carried friction pawls J2 one of which is
shown in perspective view in Figure 9. Each of the pawls J2 are provided with
angular teeth J3, J and a slot J through which a screw Je passes holding the pawl
loosely against the under surface of the radial arms. Springs J, held by the
radial arms are applied to the pawls J2 in order to rotate the pawls upon the
screws J and hold the points of the teeth J3 and J against the sides of the friction
flange J'.
When the pawl J2 is applied to the friction flange J' as represented by
the broken lines in Figure 8, the points J³ and J are not placed in radial alignment
so that the angular motion of the radial arms C in the direction of the arrow 1,
will cause the points of the teeth J3, J4, to bite against the sides of the friction
flange J and rotate the wheel J and shaft C3 and upon the reverse motion of the
arm C, the teeth J³, J, will release their hold upon the friction flange. Projecting
upward from the pawls J' are spurs J8 having bevelled or cam shaped surfaces
held in the path of the bevelled edge J10 of the flange G so that when the
flange G is moved downward by the action of the lever handle G the bevelled
edge J will be brought against the cam surfaces J and the pawls J' moved against
the tension of the spring J7 so as to release the friction flange J' from the bite of the
teeth J³ J*.
The above described method of imparting an intermittent rotary motion to a
shaft by means of a friction flange and friction pawls is not new various modified
forms of construction being already in common use.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what
we claim is :
1. The combination with a warp beam of a loom, of a shaft operatively
connected with said beam, a wheel carried on said shaft, a pawl engaging said
wheel and actuated in one direction to rotate the warp beam and deliver warp
therefrom, a spring applied to reverse the motion of said pawl and a sliding cam
plate by which the reverse movement of said pawl is limited, as and for the purpose
set forth.

page_text: 2. The combination with a warp beam, of a shaft operatively connected with
said beam, a wheel carried by said shaft, a vibrating pawl actuating said wheel, a
lever connected with the lay of the loom and actuating said pawl in one direction,
a spring applied to reverse the motion of said pawl and a sliding cam plate by
which the reverse motion of said pawl is limited as and for the purpose set forth.
3. The combination with a warp beam, of a shaft operatively connected with
said beam, a ratchet wheel attached to said shaft, a collar C capable of turning on
said shaft and having radial arms, pawls carried by said arms and adapted to
engage a wheel connected with said shaft, a wheel attached to said shaft and
engaged by said pawls to rotate the shaft in one direction, a
vibrating lever
operatively connected with the lay of the loom and acting against one of said arms
and a sliding cam plate placed in the path of one of said arms, in order to limit its
reverse motion, as and for the purpose set forth.
4. The combination with a warp beam and a shaft operatively connected with
said beam, of a wheel carried by said shaft, actuating pawls operatively connected
with the moving parts of the loom by which said pawls are moved in one direction
to rotate the warp beam and deliver warp therefrom, a spring applied to reverse the
motion of said pawls, a sliding cam plate by which the reverse motion of said
pawls is limited and a moveable frame actuating said cam plate, said frame
comprising the sliding rod F2, bar F3 attached to said rod and carrying a plate F
resting upon the warp wound on the warp beam and a bar F6 supporting said cam
plate, as and for the purpose set forth.
5. The combination with a shaft C³, operatively connected with the warp beam
of the loom, of a wheel attached to said shaft vibrating pawls engaging said wheel
to rotate the shaft in one direction and a sliding flanged collar by which said pawls
are released, as and for the purpose set forth.
6. The combination with a shaft C³, operatively connected with the warp beam
of the loom, of a wheel attached to said shaft, vibrating pawls engaging said wheel
to rotate the shaft in one direction, a collar sliding on said shaft and provided with
a flange arranged to strike said pawls and disengage the same, a pivoted hand lever
engaging said collar, an arm H³ carried by said lever and a friction cord H¹
connected with said arm and applied to resist the rotation of the shaft C3, as and
for the purpose set forth.
Dated the 26th day of June 1893.
JOHN MARSHALL LINSCOTT.
SERVULE ABRAHAM BENOIT.
Cruikshank & Fairweather,
62, St. Vincent Street, Glasgow, Agents.