Improvements in the Let-off Mechanism of Looms.
Year: 1892

page_text: Date of Application, 26th Jan., 1892-Accepted, 27th Feb., 1892
COMPLETE SPECIFICATION.
Improvements in the Let-off Mechanism of Looms.
A communication from abroad by Joux GILBERT AVERY, of Spencer, in the
State of Massachusetts, United States of America, Manufacturer.
I, JOHN CORRY FELL, of the firm of Fell and Wilding of 1 Queen Victoria
Street in the City of London, Patent Agents, do hereby declare the nature of the
said invention, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention consists in certain novel combinations of parts hereinafter set
forth and claimed. Its general object is to provide ordinary power looms with an
absolutely "positive" let-off or let-off mechanism, or, in other words, to provide
for letting off the required length of warp at each pick by the motion of the
mechanical parts of such looms, without dependence in any manner upon the
tension of the warp or upon its resistance to pressure.
Two sheets of drawings accompany this Specification as part thereof.
Figure 1 of these drawings is a perspective view of the improved let-off
mechanism as attached to one make of power-looms already in use;
Figure 2 is a sectional elevation of a central portion of the same drawn to a
larger sale;
Fi igure 3 is a large-scale face view of the ratchet-mechanism;
Figure 4 is a top view of the dog-carriers of said ratchet-mechanism projected
from Figure 3:
Figure 5 is a perspective view of the two main parts of one of the ratchet-dogs,
separated; and
Figure 6 is an elevation of this dog on its carrier.
Like reference-numbers indicate corresponding parts in the several figures.
The loom-frame, portions of which are represented at 67 and 8, in Figures 1
and 2, is the ordinary frame of a power-loom of that kind known as the "Knowles'
loom. Suitable supplemental bearings and supports, or brackets" as they are
hereinafter termed, for attachment to this loom-frame, are represented respectively
at 9 10 11 12 13 14 15 and 16, Figures 1 and 2. The ordinary main-shaft is
represented at 17, Figure 1, and an ordinary warp-beam at 18.
The ratchet-shaft of the improved let-off mechanism, represented at 19, extends
horizontally from front to rear, and is provided with a crown ratchet-wheel 20,
which conveniently faces the operator, and may have teeth as small as may be
required. A wheel 6 inches in diameter with inch teeth has been employed in
practice, and is intended to be represented. A pair of pallets or driving "dogs" 21,
in mesh with the ratchet-wheel 20, are pivoted on a pair of dog-carriers 22,
Figure 4, with their pivotal axes radial or substantially radial to the longitudinal
axis of the ratchet-shaft, and are preferably of the peculiar construction repre-
sented. See Figures 3 5 and 6. As here shown, each dog has a main point 23,
integral with its body, and a supplemental point 24, located on the back of said
main point, and connected with the body of the dog by a pivot-pin 25, which in
common with the extremities of the two points is radial to the axis of the ratchet-
shaft. The extremity of said supplemental point. 24 projects in advance of the
extremity of the main point 23 a given distance, say inch in connection with
said ratchet-wheel 20, and it is thus readily insured that one point or the other
shall be brought opposite the face of a fresh tooth by each backward movement of
the dog-carrier. In the case of the dog shown in the foreground in Figures 1
and 2 and at the left in Figure 3, such backward movement is upward. The
backward movement of the other dog is downward. As the face of the ratchet-
wheel 20 is vertical, it is necessary to throw the points of the dogs into mesh with
the ratchet-teeth by springs or the like. A single spring wire 26, Figures 3 and 6,
D

page_text: attached to the split cotter 27 by which each dog is held on the pivotal portion of
its carrier, and applied to the protruding outer end of the pivot-pin 25, and by a
screw 28 to the supplemental point 23, as shown in Figures 3 and 6, may suffice
for both points of each dog, and also to fasten in place the pivot-pins 25, which
have heads at their inner ends in this arrangement. After the wire is wrapped
around said screw 28, the screw is tightened, and each spring is thus completed.
By duplicating the dogs as well as their points, their adaptation to bite effectively
after the smallest backward movement is further increased; but the primary
object of so duplicating the dogs in this improved let-off mechanism is to provide
that one shall be working while the other is being retracted, so as to render the
transmitted motion practically continuous. The two dog-carriers are pivoted
together on the ratchet-shaft 19 immediately in front of the ratchet-wheel 20, and
between its hub and a collar 29, Figures 1 and 2, made fast on the ratchet-shaft.
The ratchet-wheel 20 is preferably loose on the ratchet-shaft 19, and connected
therewith by a sliding clutch 30, Figures 1 and 2, splined to said shaft 19, and
constructed with teeth at its front end which normally mesh with like teeth, 31
Figure 2, on the rear end of the hub of said ratchet-wheel; and said clutching
teeth are preferably similar in form and width to the crown ratchet-teeth, (only
reversed on the hub of the wheel,) so as to prevent any considerable lost motion
when the ratchet-wheel is re-clutched. A fork 32, carried by a short horizontal
pivot-shaft 33, engages in a customary manner with the clutch 30, and is actuated
by a hand-lever 34, which projects forward from said pivot-shaft within easy reach
of the operator from the front of the loom, and serves by its gravity to render the
ratchet-wheel normally clutched. By lifting the handle-end of the lever, the
ratchet-wheel is unclutched from the ratchet-shaft, which may then be turned
independently, by means of a hand-wheel 35, Figure 1, fast on its front end, for
turning the warp-beam by hand; said hand-wheel 35 being so located as to be
operated, in common with the clutch-lever, and simultaneously therewith, from in
front of the loom.
Motion is transmitted from the ratchet-shaft 19 by means of a worm 36 fast
thereon, and a worm-wheel 37 fast on a vertical "worm-shaft" 38, which in turn
carries a worm 39, Figure 1, in mesh with a large worm-wheel 40 fast on the
spindle of the warp-beam 18.
The worm-shaft 38 carries another worm, 41, in mesh with a small worm-
wheel 42, fast on a short horizontal shaft 43, parallel with the warp-beam 18,
which in turn carries a worm, 44 meshing with a small worm-wheel 45, which,
by a set screw, 46 Figure 2, for example, is made fast on a shaft 47 parallel
with the ratchet-shaft 19. Said shaft 47, which is hereinafter termed the
graduator-shaft," may be and is thus located above the horizontal ratchet-
shaft 19, and at the same time be driven through wheels of small diameter, so as
to be readily accommodated on all or most looms as now made.
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The graduator-shaft 47 is screw-threaded, and provided with a loose screw-
nut 48, hereinafter termed the "graduator-nut," which, in the arrangement
shown, travels forward, under the action of the screw-thread, as the warp is
unwound. For returning said graduator-nut by hand when a new warp-beam
is introduced, the rear end of the graduator-shaft is provided with a hand-wheel 49
for example and the worm-gearing is adapted to be disconnected or unclutched,
as for example by partially unscrewing said set-screw 46, so as to loosen said
worm-wheel 45 on the graduator-shaft.
The graduator-nut 48 is constructed with a wing or wings, and. provided with
holes 50, in vertical series, therethrough, for adjusting a screw-bolt 51, which passes
through a slot 52 in a substantially vertical "graduator-lever" 53, as means for
moving it by said nut, and for keeping the nut from turning. The fulcrum of said
graduator-lever is a screw-bolt 54, Figure 1, adjustable vertically in a fulcrum-
support 55, by means of series of holes 56 57 in the lever and in said support
respectively, and said fulcrum-support is itself adjustable horizontally by means of
a series of holes 58 in said bracket 14, through which its attaching bolts 59 pass.

page_text: The lower end of the graduator-lever carries a screw-bolt for example, shown
at 60, which works in a slot 61 in a substantially horizontal "transmitting-
lever" 62, as a movable fulcrum for this lever, which is the central and main
device for transmitting motion to said dog-carriers 22 of the ratchet-mechanism.
The motion of said lever 62 is steadied by a shouldered stud 63 projecting from said
bracket 15 through a slotted enlargement 64 of the lever, and provided with a
cap-nut and washer.
For actuating the ratchet-dogs from the main-shaft 17 of the loom, a spur-
wheel 65 Figure 1, is made fast on the shaft inside the loom frame at the right
hand end, where all the attachments are located; a second spur-wheel, 66, one-
half its diameter, is supported in mesh therewith by a short stud-shaft 67 projecting
parallel with the main-shaft from said bracket 16, and provided with a pair of
crank-pin holes 68 at diametrically opposite points a crank-pin 69 in the form
of a screw-bolt is made fast in one of said holes; and a pitman 70 connects
said crank-pin 69 with a pivotal screw-bolt 71 carried by the front end of said
transmitting-lever 62; while a shackle 72, attached to the rear end of said
transmitting-lever, is connected, by a pair of curved links 73 and pivotal screws,
to a pair of shackles 74, which embrace the pivotal extremities of the respective
dog-carriers 22, on which they are held in place by split cotters. This completes
the mechanism, as shown in the accompanying drawings.
Said brackets 9 to 16, in common, are tightly bolted to the ordinary loom-frame,
and are readily conformed to the requirements of any particular make of loom.
Ordinarily the mechanism proper will require no other modification or adaptation
in applying it to looms of different makes. The ratchet-shaft 19 is supported by
the brackets 9 and 10; the long worm-shaft 38 by 11 and 12, and by the customary
step-bearing in the flat tie-bar 6* at the bottom of the loom; the graduator-
shaft 47 by the brackets 9 and 13; the graduator-fulcrum-support 55, steadying-
stud 63 and stud-shaft 67 by 14 15 and 16, respectively, as aforesaid; and the
remainder of the let-off' mechanism by said bracket 9, in the present arrangement.
Details of these brackets and of other parts which have not been specified are
ordinary mechanical details known to skilled machinists.
With a full warp-beam in the loom at 18, the movable fulcrum 60 at its starting
point, and the mechanism as a whole in working order, at each stroke of the lay,
or each half turn of the main-shaft 17, motion is transmitted through the described
connections to the transmitting-lever 62, and therefrom through the connections 72
73 74 to the dog-carriers 22 and dogs 21, so that one dog is caused to make its
effective stroke while the other is being retracted as aforesaid. The ratchet-
wheel 20 is thus slowly turned, and therewith the ratchet-shaft 19 and its worm 36;
the latter in turn driving the worm-wheel 37, and therewith the worm-shaft 38 and
its worm 39, which, in mesh with the worm-wheel 40 on the warp-beam spindle,
lets off the proper length of warp for a pick, in a
"positive manner. Simul-
taneously with the movement of the warp-beam, motion from the same source is
transmitted through said worm-shaft 38 and the worm-gearing at 41 to 45 to the
graduator-shaft 47, and the latter by its screw-thread actuates the graduator-
nut 48; this nut in turn moving the graduator-lever 53, and thereby shifting said
movable fulcrum 60, so that the next half-turn of the main-shaft shall transmit to
the dogs 21 a stroke increased to the necessary infinitesimal extent.
By properly proportioning the parts, and by making suitable preliminary adjust-
ments as at 51 54 and 59, to suit the individual loom and the "heft" of warp-beam
that is to be used, it is possible to empty the warp-beam without further attention
to the let-off mechanism, unless a "pick-out" or like accident occurs. In this
event, the ratchet-wheel 20 is unclutched (as in Figure 2) and motion from the
hand-wheel 35 is transmitted through the ratchet-shaft 19, worm 36, worm-
wheel 37, worm-shaft 38, worm 39 and worm-wheel 40 to the warp-beam until the
loom is ready to start, when the ratchet-wheel is re-clutched, and the operation
proceeds as before. Finally, after a warp-beam is emptied, (as in Figure 1,) the

page_text: worm-wheel 45 is loosened, by means of the set-screw 46 or its equivalent, and
motion is directly transmitted from the hand-wheel 49, through said shaft 47 nut 48
and lever 53, to said movable fulcrum 60, to readjust the latter for the beginning
of the next weaving operation; after which adjustment, said wheel 45 is imme-
diately made fast again.
By making each of the dogs 21 double-pointed in the particular manner above-
described, the ratchet-wheel is actuated with absolutely unvarying leverage;
making and keeping the points of the required minute difference of length is
readily accomplished, and lost motion at the pivots is reduced, as compared with
ordinary arrangements.
By employing a pair of such dogs working alternately, as above described, and
thus rendering the movement of the ratchet wheel, and consequently that of the
warp-beam, practically continuous as aforesaid, the mechanism is moreover freed
from the excessive wear due to overcoming inertia in ordinary ratchet-mechanisms.
By employing double worms at 36 and 39 as shown, and thus turning the worm-
wheels 37 and 40, respectively, two teeth to each rotation of the respective worms,
an easier movement is obtained than could be had by reducing the relative
diameters of the wheels so as to get the same movement of the warp-beam.
If it be preferred to actuate the ratchet-dogs from the lay, a suitably proportioned
bell-crank lever and links, connecting the lay with said transmitting lever 62 or its
equivalent, may take the place of said gearing 65 66 crank-pin 69 and pitman 70;
other adjusting devices may take the place of said series of holes and screw bolts
at 50 51 54 56 58 and 59; and numerous other like modifications will suggest
themselves to skilled machinists.
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) In combination with a crown ratchet-wheel 20 and its shaft 19, and with a
suitable dog-carrier 22 pivoted on said shaft, in a let-off mechanism for looms,
a ratchet "dog
21 having a main biting-point 23 integral with its body, and a
supplemental biting-point 24 projecting in advance of said main point, and pivoted
to the body of the dog by a pin 25 radiál to the axis of said shaft, the extremities
of both points being also radial to said axis, and in contact with the teeth of said
wheel, substantially as shown in Figures 3 5 and 6, so that one point or the other
shall catch a tooth of said wheel at each driving stroke of the dog.
(2) The combination with one and the same crown-ratchet-wheel 20 and its
shaft 19, in such a let-off mechanism, of a pair of simultaneously-oscillated dog-
carriers 22 pivoted on said shaft, and a pair of such double-pointed ratchet-
dogs 21, (Claim 1,) pivoted on the respective carriers, so that the two dogs make
their driving strokes alternately, and the let-off of warp while the loom is at work
is practically continuous.
(3) In such a let-off mechanism, the combination with a horizontal ratchet-
shaft 19 extending from front to rear, and a crown ratchet-wheel 20 loose on said
shaft, of the clutch and clutch-teeth 30 31, fork 32, pivot-shaft 33, and hand-
lever 34, together with a hand-wheel 35 fast on the front end of said ratchet-shaft,
substantially as hereinbefore described with reference to Figures 1 and 2, to
facilitate turning the warp-beam by hand when this is necessary.
(4) In such a let-off mechanism, the combination with the dog-carrier or dog-
carriers 22 of the transmitting-lever 62, having the slot and slotted-enlargement 61
64, the movable-fulcrum 60 and steadying-stud 63 in the slots of said lever, and
the aforesaid shackles 72 74 links 73 and pivot-bolts connecting said lever with
said carrier or carriers, substantially as hereinbefore described with reference to
said Figures 1 and 2.
(5) The combination, in such a let-off mechanism, of the spur-wheel 65 made
fast on the main-shaft of the loom, the spur-wheel 66 one-half the diameter of said

page_text: spur-wheel 65, having a stud-shaft 67 and a crank-pin 69, and the pitman 70
coupled to said crank-pin and to said transmitting-lever 62, substantially as herein-
before described with reference to said Figures 1 and 2.
(6) The combination, in such a let-off mechanism, of a horizontal screw-threaded
graduator-shaft 47, a graduator-nut 48 on said shaft, an adjustable screw-bolt. 51
carried by said nut, a substantially vertical graduator-lever 53, an adjustable
fulcrum 54 for said graduator-lever, and an adjustable fulcrum-support 55, sub-
stantially as hereinbefore described with reference to said Figures 1 and 2, said
graduator lever carrying said movable fulcrum 60.
(7) The worms and worn-wheels 36 37 41 42 44 and 45, in combination with
the worm-shaft 38 and short-shaft 43, for transmitting motion from said ratchet-
shaft 19 to said graduator-shaft 47 in the manner hereinbefore set forth with
reference to said Figures 1 and 2.
(8) The set-screw 46, or any mere equivalent thereof, in combination with said
worm-wheel 45 and graduator-nut 48 and the hand-wheel 49 on said graduator-
shaft 47, and with said graduator-lever 53, for quickly returning said movable-
fulcrum 60 to its starting point when a new warp-beam is introduced, substantially
as hereinbefore described with reference to said Figures 1 and 2.
65
(9) A positive" let-off mechanism in which motion is transmitted to the warp-
beam 18 from a horizontal ratchet-shaft 19, said ratchet-shaft receives its motion
from the main-shaft of the loom through the medium of ratchet connections
including a transmitting-lever 62 having a movable-fulcrum 60, said fulcrum 60 is
automatically shifted by a graduator-shaft 47 through the medium of adjustable
connections, and said graduator-shaft receives its motion from the same ratchet-
shaft, substantially as hereinbefore described and as represented on the accom-
panying drawings.
Dated this 26th day of January 1892.
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.