Improvements in Let-off Mechanism for Looms.
Year: 1896

page_text: Date of Application, 20th Oct., 1896-Accepted, 21st Nov., 1896
COMPLETE SPECIFICATION.
Improvements in Let-off Mechanism for Looms.
I, ARTHUR ALLAN FORBES, Cloth Finisher, residing at 94 St. Margaret
Street, St. Hyacinthe, Province of Quebec and Dominion of Canada, do hereby
declare the nature of my invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
My invention relates to devices for governing the automatic reduction of the
tension of the yarn upon the yarn or warp beam of a loom, and has particular
reference to devices of the above indicated class in which the reduction of the
tension is obtained by means of a weight or car moving upon a lever which is
connected to the friction bands upon the heads of the beam.
The object of my invention is to provide a means whereby the reduction of tension,
called for in consequence of the unwinding of the yarn from a loom warp beam,
and consequent change in diameter and power of purchase, can be governed auto-
matically and correctly from a full to an empty beam with one setting of a
nechanism on the weight and lever principle, the mechanism having no connection
whatever with any running or moving part of the loom, except the free roller
which bears against the warp on the beam for the purpose of controlling, corre-
sponding to the reduction of the diameter of the warp on the beam, the time taken
by a loaded car to travel a predetermined distance towards a lever's fulcrum,
said distance being determined by the number of teeth in the gear which meshes
with the toothed bar on the end of which the free roller operates against the yarn
on the beam, all the parts being so arranged, that the operator cannot without
using a tool put in fewer picks of filling per inch than the mechanism is set and
loaded for.
Other features of the invention will appear from the description following herein-
after and from the appended claims.
Reference is to be had to the accompanying drawings forming a part of this
specification, in which similar letters of reference indicate corresponding parts in
all the figures.
Figure 1 is a broken rear elevation showing one end of a loom provided with
the improvement;
Figure 2 is a broken plan view of the same;
Figure 3 is a sectional elevation on the line 3-3 of Figure 2;
Figure 4 is a side elevation, with parts in section on the line 4-4 of Figure 1;
Figure 5 is a broken detail view of a counter-balancing lever; and
Figure 6 is a detail sectional elevation showing one end of the friction band.
On the beam A is wound the yarn B, against which presses a free roller C,
whose axis extends parallel to that of the beam. The roller C is journaled in a
support or fork D which is made integral with a rack E having sliding movement
in a frame F toward and from the beam. The rack E is provided with an
aperture E' into which may he put a pin E connected to the frame F by means
of a chain E³ or a like connection, for a purpose to be stated hereinafter. The
rack is also provided with a groove or guideway E' which extends longitudinally,
and is engaged by lugs G which have sliding movement in the frame F in a
direction substantially parallel to the axis of the beam A. A screw H, which
engages a screw threaded socket in the frame F and has a head loosely rotating
in the connecting rod G¹ of the lugs G, serves to move the said lugs and the

page_text: rack E in a direction parallel to the shaft of the beam, to bring the teeth of the
rack into or out of engagement with those of a pinion I, mounted on a vertical
shaft J, journaled in the frame F, the lower end of the said shaft carrying a
bevel wheel K gearing with a similar wheel L on a horizontal shaft M, which
extends forwardly at the bottom of the loom. The pinion 1 is removable, and a
set of change pinions furnished with each let-off mechanism.
On the shaft M is rigidly secured a pulley P, which receives the wire or rope R
passing over a pulley S, one end of the said wire being secured to the pulley P,
and the other end to a weight T. The opposite end of the shaft M to that
carrying the bevel wheel 1 is provided with a bevel wheel V meshing into a
similar wheel W located upon à horizontal shaft X which extends longitudinally
of the loom, that is, parallel to the beam A. On the said shaft X is rigidly
secured a pinion Y engaging in another pinion Z which is loose upon a shaft a
located above the shaft X and parallel thereto. The shaft X is provided with a
square end U adapted to receive a wrench or crank U for the purpose of turning
the shafts X and M and raising the weight T. A pawl O made integral with or
rigidly secured to a collar loosely mounted on the shaft a is adapted to engage
with a ratchet wheel N rigid upon the shaft X, to prevent return movement of
said shaft.
To the shaft a are rigidly secured pulleys b, to each of which is connected one
end of the friction band c encircling the head d of the beam, it being understood
that there is a friction band for each head. The other end of each friction band
is secured to the frame of the loom. The friction band may be adjusted by
means of a rotatable double-threaded screw or fastener c' screwing into female
threaded sockets C².
On the shaft a are also rigidly secured two arms or levers e, between which is
arranged a sleeve f which is made integral with the pinion Z, and also has rigidly
secured to it a sprocket wheel g. Another sprocket wheel g' is journaled in the
opposite or free ends of the leverse and a chain A passes over the said sprocket
wheels, adapted to be engaged by a projection from a car i which is provided
with rollers, adapted to run upon the levers e, the said levers forming a track
for the car. The shaft of the sprocket wheel g¹ is mounted in slots e', extending
longitudinally in the levers e so that the chain may be readily drawn tight. The
car is locked so that the operator cannot interfere with the weights.
The levers e are provided with abutments j adapted to engage with the car i
upon its outward travel. On the shaft a is further rigidly secured an angular
off-set I carrying the anti-friction roller m, the latter being adapted to engage
one end of a lever n, fulcrumed at o upon a bracket p. The lever n is provided
with a longitudinally slidable weight 9 which may be adjusted in any suitable
manner and is for the purpose of balancing the levers e on which the car i travels
before the car is put on the levers, so as to insure a true reduction from the
moment the car leaves the abutments j.
e
The rack E has five teeth to the inch and when set with the pin E' as directed,
the face of roller C is nine inches from the centre of beam A. The length of
levers from the centre of shaft a to abutments is 304 inches, the half inch
being taken up by half the diameter of the car wheels, the centre of hind wheels
of car i when run out to abutments j being thus 30 inches from the centre of
shaft a which forms the levers' fulcrum. A full beam is assumed to be 18 inches
in diameter, an empty beam 6 inches in diameter, thus rack E moves 6 inches and
30 teeth from a full to an empty beam, and with a 30 tooth pinion I in mesh with
the rack E the surface speed of sprocket wheel g is five times greater than the
surface speed of the 30 tooth piniou I, and forward motion of rack E, thus when
rack E moves one tooth car i moves one inch, and one revolution of pinion I
with 30 teeth, and of course six inches and 30 teeth of rack E would bring the
centre of the hind wheels of car i to rest on the centre of shaft a, if that were
possible or necessary. It will be understood that the rule of the mechanism
is 900, thus a 45 touth pinion I would bring the centre of the hind wheels of a

page_text: car i 20 inches towards the levers' fulerum, a 40 tooth pinion 22 inches and so
on, the set of change pinions I, the pin E, abutmenta j, and the balance lever n
enabling the mechanism to be set to suit any usual make of loom, on any class of
goods. Of course, the measurements, relative speeds, and rale given could be
altered to suit circumstances with which they would be unable to comply.
The operation is as follows :-
The attendant of the machine first sets the pawl O in engagement with the
ratchet wheel N, and then rotates the screw H to remove the rack E from contact
with the pinion I, and the rack E is then slipped back until the yoke D substan-
tially abuts against the frame F, so as to be out of the way when putting in a full
beam. The end of the shaft X projects through its bearings, and is squared for
the purpose of using a wrench or small crank U with which to turn the said
shaft X, which motion will be communicated to the shaft M on which is rigidly
secured the pulley P, to which one end of the wire R is made fast, and on which
the wire R is wound raising the weight T to its highest position, and at the same
time moving the car i outward upon the track formed by the levers e, until said
car i engages the stops or abutments j, the pawl O acting on the ratchet wheel N
preventing a return movement of the weight T, the pulley P, the shafts M, and X,
and the car i. Thereupon the rack E is drawn forward and the pin E is inserted
in the aperture E', the rack E is then pushed backward until the pin E³ abuts
against the frame F. When the weight T, the car i and the rack E are in the
aforesaid positions, the screw H is turned to bring the teeth of the rack E in
engagement with the teeth of the pinion I and thereupon the pawl O is thrown
back as illustrated. This will release the shaft X, and under the influence of the
weight T, the shaft M will be rotated and the rotation will be communicated to
the shafts J, X and the sleeve f so that the roller C will be projected towards the
beam A, while the car i will be caused to travel toward the fulcrum of the
levers e, that is, the shaft a. This motion will continue until the roller C strikes
the yarn B on the beam A.
It will be obvious that a predetermined position of the car i will always corre-
spond to a certain position of the roller relative to the centre or axis of the
beam; that is, the leverage exerted by the weighted car i will have a predeter-
mined relation to the distance of the roller C from the centre of the beam. When
the roller C has come in contact with the yarn B it will gradually follow the
reduction in thickness which ensues as the yarn is reeled off the beam, and simul-
taneously the car i will travel toward the shaft a, it being obvious that as the car
approaches the said shaft, the leverage of the weight represented by the said car
will be decreased, and the friction bands c will be gradually drawn less tight
against the circumference of the heads d, so that friction will be reduced to
correspond to the reduction in diameter of the yarn on the beam. It will be
understood that the weighted levers e constitute a tension device for the friction
bands c.
It will be understood that the ratio of the motion of the car i toward the lever's
fulcrum to that of the roller C toward the beam's centre, may be varied according
to the requirements of each individual case by employing pinions I of different
numbers of teeth, and the mobility of the rack E toward and from the said pinion
facilitates the removal and exchange of the latter.
It will be obvious that it matters not whether there be a thick or a thin layer of
yarn upon the beam A, as by means of the pin E, or equivalent stop of the
rack E always deciding the distance of the roller C from the centre of the beam A
and the abutment j on the levers e or equivalent stop of the car i always deciding
the distance of the said car i from the centre of the shaft a, said roller C and car i
on hitting the pawi O and freeing the ratchet wheel N, will, through the influence
of the weight T, find their correct relative positions, which are governed by the
number of teeth on the pinion I which meshes with the rack E, and travel their
corresponding and predetermined distances until all the yarn is delivered from
the beam.

page_text: The lever the down end of which fits into the angular off-set is for the
purpose of easing the friction sufficiently at any time there should be pick backe,
and the catch is for the purpose of holding the lever k in position, and so set
that the friction bands will be relaxed only sufficiently to turn back the beam with
ease after picking out, and no more, so as to give as little opportunity as possible
for change of grip and tension when the friction is again applied.
I also provide a gauges adjacent to one of the levers e, for the purpose of
ascertaining if the lever is horizontal or how far it is from being so at any time.
In order to hold up the levers e while attaching or detaching the friction bands c,
the gauge s is perforated at intervals, and a pin t is provided for insertion in said
perforations, to hold the lever in the desired position. The gauge is set on the
inner side of the inside track of the levers e, that is the side adjacent to the
loom frame.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. A let-off mechanism for looms, comprising a shaft arranged lengthwise of the
warp beam and carrying pulleys b, friction bands engaging the heads of the beam,
band holders o connecting said bands to said pulleys, levers e rigidly secured to
the aforesaid shaft and provided with abutments i, a gauge s for ascertaining the
position of the said levers e, the pin or holder t for supporting the said levers, the
car or weight mounted to travel on said levers e and to engage with said abutments j,
a rack E movable toward and from the warp beam and carrying a follower, such
as a roller to engage the warp, said rack being provided with an aperture E', a
pin E2 adapted to be inserted in said aperture to collide with the frame and thereby
limit the movement of the rack and determine the position thereof, a change
pinion I engaging in the said rack and operatively connected to the aforesaid car,
so that the rack and car may move in unison, means for imparting motion to the
rack and car, a ratchet wheel N operatively connected to the car so as to turn when
the car travels on the levers e and a pawl O adapted to engage said ratchet to
prevent rotation thereof in one direction and thereby temporarily prevent the
return movement of the car, substantially as shown and described.
2. In a let-off mechanism for looms, a shaft arranged lengthwise of the warp
beam and carrying pulleys 6 friction bands engaging the heads of the beams, band
holders c' connecting said band to said pulleys, levers e rigidly secured to said
shaft, a car or weight i travelling on said levers, an angular offset / rigidly secured
to said shaft, a lever k secured to said angular offset, a catch for holding the
lever stationary, an anti-friction roller m carried by said angular off-set, a
stationary bracket, a balance lever n fulcrumed in said bracket and engaging with
said anti-friction roller, and a slidable weight y on said balance lever, substantially
as shown and described.
Dated this 20th day of October 1896.
A. M. & WM. CLARK,
53 Chancery Lane, London, Chartered Patent Agents.