US2226232A - Control for loom letoffs - Google Patents

Description

Dec. 24, .1940. o. v. PAYNE CONTROL FOR LOOM LE'I'OFFS 2 Sheet-Sheet' 1 Filed Nov. 13, 1939 |NVENTOR OSCAR V PAYNE M ATTORNEY Dec. 24, 1940. O PAYNE 2,226,232

CONTROL FOR LOOM LETOFFS Filed Nov 13, 1339 2 Sheets-Sheet 2 FIE. E

J-ruwnmron 05cm: V. PAYNE ATT O'RNEY Patented Dec. 24, 1940 UNITED STATES 2,226,232 I i CONTROL FOR 1.00 LETOFFS Oscar V. Payne, Leicester, Mass, assignor to Crompton & Knowles Loom Works, Worcester, Mass., a corporation of Massachusetts Application November 13, 1939, Serial No. 304,157 11 Claims. (Cl. 139-110 This invention relates to improvements in letolf mechanisms for looms and it is the general object of the invention to provide means which will automatically relieve the warp and cloth of the strain imposed upon them by the letoff when the loom stops.

In those forms of letoff'mechanisms for looms which employ a weight or its equivalent there is generally present a backwardly-exerted strain on the warp thread which resists the forward advance of the cloth by the take-up mechanism, thereby maintaining desirable tension on the warp threads. When very fine fabrics are being woven and the loom stands at restfor any length of time a letoff of this type acts to draw the fell of the cloth rearwardly so that upon resumption of weaving the first few picks of weft to be laid are beaten in too closely to the picks laid immediately before weaving stopped, thus producing a so-called thick place. It is an important object of my present invention to providemechanism acting automatically and preferably controlled from some part which has a movement when the loom stops to prevent the letoff from exerting sufficient rearward pull on the warp threads to change materially the position of the fell of the cloth. a

In my prior Patent No. 1,803,143 I show a pawl which is moved manually into holding position with respect to a rack secured to a part of the letoff mechanism which turns with the warp beam against the action of a weight. In that construction the pawl moves about a fixed axis and is likely to be located at a point between two teeth and unable to engage either tooth until the weight has induced rearward turning of the warp beam sufficient to move one tooth to the pawl. This rearward turning, however, disturbs the setting of the fell of the cloth and it is a further object of my present invention to provide locking means for the letoif which moves to locking position immediately upon loom stoppage without requiring backward motion of the beam and regardless of the angular position of the ratchet. This result I accomplish as set forth hereinafter by moving the pawl bodily toward the ratchet a sufiicient distance to insure engagement with one or another of the ratchet teeth.

In some instances the pawl will move only a short distance before engaging a tooth while in other instances the pawls will move a considerable distance before reaching locking position. I

The part of the loom which moves" when the loom stops, such for instance as the shipper handle, moves through a definite distance which cannot ordinarily be changed to accommodate the motion of the pawls bodily toward the ratchet teeth. It is another object of my presentinvention to provide a yielding element in the train of mechanism connecting the shipper handle with the letoff which can be adjusted to transmit suficient force to lock the letofi' mechanism and then yield to permit further movement of the shipper handle.

With these and other objects in viewwhich will appear as the description proceeds, my invention resides in the combination and arrangement of parts hereinafter described and set forth.

In the accompanying drawings, wherein a convenient embodiment of my invention is set forth:

Fig. 1 is a side elevational part of a loom showing a letoff and my improved controller therefor in letoff locking position, I

Fig. 2 is a detail rear elevation taken in the direction of arrow 2, Fig. 1, I v

Fig. 3 is adetail horizontal section on line 3-3 of Fig. 1,

Fig. 4 is a detail plan looking in the direction of arrow 4, Fig. 1,

Figs. 5 and 6 are detail rear elevations looking in the directions of arrows 5 andfi, respectively, Fig. 1, and

Figs. 7 and 8 are diagrammatical views showing themotion of the locking pawls as they move relatively to the ratchet with respect to which they cooperate.

Referring to the drawings, particularly Fig. l, Ihave shown a loom frame III in the forward part of which ismounted a shipper shaft II to which is secureda shipper handle [2. An arm lit-secured to and depending from the shipper shaft moves to the left when the shipper handle is pulled forwardly or to the right as viewed in Fig. 1 to cause loom operation, and moves to the right when the shipper handle rocks in the opposite direction to stop the loom.

Extending rearwardlly from'the loom frame is a bracket 15 on which is mounted a warp beam l6 supplying warp thread W extending forwardly toward weaving instrumentalities not shown. Associated with the warp beam is a letofi mechanism L having an arcuate segment I! fora cable or rope [8 the lower end of whichis attached to a variable weight I9. The leto-fi' mechanism includes in its construction a plate 20on which are .cast a series of ratchet teeth 2| and a shaft 22 supported by the plate has keyed thereto a worm 23 which meshes with a worm Wheel 24 secured to the warp beam. The gudgeon 25 of the warp beam rotates in a bearing 25 supported by the bracket [5.

The particular form of letoff which I illustrate at the left part of Fig. 1 may be the same as that shown in my prior Patent No. 1,803,143 and of itself forms no part of my present invention except as it cooperates with parts to be described hereinafter. It is thought sufficient for an understanding of my present invention to state that rotation of the warp beam in a clockwise direction as viewed in Fig. l to unwind warp thread is accompanied by a corresponding rotation of worm gear 24 which transmits a force throughthe worm 23 to plate 23 to turn the latter to the right and thereby raise the weight I9. When a predetermined amount of angular motion of the warp beam has occurred mechanism not shown herein but set forth in my prior mentioned patent acts to turn the worm in such a direction as will permit descent of the weight l9, after which said weight will again start to rise as more Warp thread is consumed.

The matter thus far described may be of the usual construction and of itself forms no part of my present invention.

In carrying my present invention into effect I provide the bracket with a depending arm 30 onwhich a lever 3! is pivoted as at 32. An adjustable rod 33 pivoted to the lever at 34 extends forwardly and is pivoted at 35 to arm l3 on the shipper shaft H. A slot 33 in arm I3 permits adjustment of the pivot 35 toward and from the shipper shaft II.

The lower end of lever 3| is pivotally connected as at 43 to a rod guide 4| having a sleeve 42 through which extends a rod 43. An adjustable collar 44 on the rod 43 engages the forward end of the sleeve 42 to limit rearward motion of the rod and also to cause the rod to move forwardly when lever 3| rocks in a counterclockwise direction as viewed in Fig. 1. A compression spring 45 surrounds the rod 43 and extends from the rear end of the sleeve 42 to a second collar 43 adjustably secured on rod 43.

The locking mechanism for the letoff is operated by rod 43 and as set up more particularly in Figs. 2, 3 and 4 comprises a stud 53 secured in the bracket l5 by set screw 5|. Mounted on this stud is the. eccentric hub 52 of a lever 53 pivotally connected as at 54 to the rear end of rod 43. In the present instance I show a lock which, is adaptable to letoif mechanisms now in use having relatively large ratchet teeth, but for new constructions the ratchet teeth could be smaller and use a single pawl. Mounted on the eccentric hub 52 as shown particularly in Figs. 2 and3 are three pawls 55, and 55 and 51 of different lengths so that one or another of them Will be able to engage a tooth 2! with a very small motion of the pawls toward the teeth. Each pawl has a small ear 30' and a light tension spring 5| the forward end of which is held by a wire 52 connected to a link 63 the forward end of which may be attached-to the depending arm 30. Each pawl also has a lug 65 for engagement with a stop pin 65 carried by lever 53. The springs of the several pawls hold their respective lugs 55 against the stop pin under normal operatingconditions but when the loom is stopped the pin 56 is moved away from the lugs 65 so that the springs will tend to rock the pawls in a clockwise direction around eccentric 52 and stud 53 as viewed inFig. 1 toward the ratchet teeth 2|.

In operation, the shipper handle will be pulled forwardly to start the loom and act through the connections described to move rod 43 to a relatively forward position by a force transmitted positively through sleeve 42 and collar 44, thereby rocking lever 53 positively and moving the stop pin against the lugs 65 to hold the pawls spaced from the ratchet teeth 2| against the action of their springs 51. When in this position lever 53 is forward and the parts are as shown in full lines in Fig. '7 and. the letoiT delivers warp in a manner already described.

When the loom is stopped the shipper handle and shipper shaft I [turn in a counter-clockwise direction to the position shown in Fig. 1 and move sleeve 42 rearwardly to compress spring 45. During this rearward motion of the sleeve 42 force is transmitted yieldingly through spring 45 and collar 45 to move the rod 43 in a backward direction and rock lever 53 rearwardly or in a clockwise direction. When the parts reach the dotted line position in Fig. 7 the pawls are in engasemjentwith the teeth 2!.

The pawls can move toward the ratchet while theratchet teeth are in any one of a number of angular positions with respect to the axis of the letcff mechanism and there is no assurance that any one of the pawls will be in position for immediate engagement with a tooth shoulder 10. Assuming as one condition of operation, however, that one of the pawls is against a shoulder l0 as, shownin Fig. 7, continued rearward movement of sleeve 42 will cause compression of Spring 45 and this. compression will continue until the shipper handle has reached its. normal off position. Thev spring 45 is relatively light and offers no. objectionable resistance to. the motion of the shipper handle. Under this assumed condition, therefore, one of the pawls will be in engagement with a tooth to support weight l9 and spring 45 .willbe subjected to a relatively large compression.

Assuming on the other hand that when the pawls .move to the dotted line position of Fig. 7 none of them is sumciently near a shoulder 15 for immediate holding engagement with the ratchet, continued rocking of the shipper handle will move the rod 43 rearwardly and rock the lever 53 to the left from the dotted line position of Fig. 7. During this rocking of'lever 53 the wide part of the eccentric moves to the left and acts to move the pawls bodily in a direction toward the ratchet. The extent of this motion of the pawls toward the ratchet will be sufficient because of the proportions of the eccentric to move one or another of the pawls into engagement with a shoulder 70. If this engagement occurs before the shipperhandle has reached its full off position there will be a slight compression of spring 45 to accommodate the excess motion of the shipper handle. In Fig. 8 the full line position corresponds to the dotted line position of Fig. 7, and the dotted line position corresponds to the extreme left hand position which lever 53 can occupy if the pawls have tobe moved bodily a considerable distance to cause engagement between one of them and a shoulder 10.

I find that the mechanical advantage due to the proportions of the lever 53 and the eccentric are sufiiciently favorable to permit the use of a light spring 45 and that the latter will exert sufiicient rearward force to prevent turning of the lever 53 by a force'transmitted from the shoulder and through a pawl to'the eccentric. In this connection it is interesting to note that under the first assumption previously made the eccentric does not move very far and there -is a relatively large force directed from the'ratchet toward the eccentric tending to turn the lever 53 in a counter-clockwise direction, but under this condition the spring 45 is under a relatively high degree or compression and therefore o-fiers considerable resistance to any turning of lever 53 which might be induced by the weight l9 acting through the ratchet; On the other hand, under the second of the previously made assumptions the eccentric swings toward a position between stud 50 and the ratchet and the turning moment acting on lever 53 is comparatively small and can be resisted by the spring 45 even thoughthe latter is under a lesser degree of compression than that existing under the first assumption previously made. r. I l

From the foregoing it will be seen that I provide a look for the letofi mechanism which is moved by some part of the loom which moves when the loom stops to a position to support weight l9 and prevent the latter from subjecting the warp threads to improper strains during periods of idleness. It will also be seenthat the force which moves the locking pawls into position is transmitted yieldingly through the spring 45, thereby making unnecessary fine adjustments to accommodate the motion of the shipper handle to the motion of the pawls. It will further be seen that the eccentric acts to move the pawls toward the ratchet teeth 2|, thereby giving assurance that at least one of the pawls will be in holding position with respect to a tooth 2| when the shipper handle is in non-running position, thereby preventing any descent of weight l9. The mechanical advantage due to the eccentric enables a comparatively light force exerted by spring 45 to support the weight [9 and prevent rearward displacement of the fell of the cloth. Again, the stop pin 66 serves topull the pawls out of locking position whenever the shipper handle is moved to running position, but releases the pawls so that they can be moved toward the ratchet teeth 2| bytheir springs as soon as the shipper handle moves away from running position.

It will also be seen that a compensating relation exists between the degree of compression of spring 45 and the amount of angular motion on the part of the eccentric, a position of the eccentric which permits weight I9 to exert a relatively large force tending to turn lever 53 being resisted by a high compression of spring 45, while a location of the eccentric so that a smallv turning force only can be exerted by theweight on the lever 53 corresponds to a lighter degree of compression of the spring 45.

Having thus described my invention it willbe seen that changes and modifications may be made therein by those skilled in the art without departing from the spirit and scope of the invention and I do not wish to be limited to the details herein disclosed, but what I claim is:

1. In a loom having a part which moves when the loom stops and having a letoff mechanism provided with a member rotatable with the warp beam against the action of a weight as warp is consumed, the weight normally exerting a continuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprising locking mechanism for the member normally in non-locking position, and means controlled by the part when the latter moves due to loom stoppage to move the locking mechanism into locking relation with respect to the member and prevent reverse rotation of the latter by the weight.

2. In a loom having a stationary frame and a part which moves when the loom stops and having a letoif mechanism provided with a member rotatable with the warp beam against the action of a weight as warp is consumed, the weight normally exerting a continuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprising locking mechanism for the member including a device movable with the member and a second device mounted on the stationary frame of the loom, said device normally disengaged, and means controlled by said part when the latter moves due to loom stoppage to cause cooperation between the two devices to prevent reverse rotation of the member by the weight.

3. In a loom having a part which moves when the loom stops and having a letoff mechanism provided with a member rotatable with the warp beam against the action of a weight as warp is consumed, the weight normally exerting a continuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprising a series of ratchet teeth movable with the member, a pawl normally disengaged from the teeth, and means connecting said part and the pawl to move the latter into engagementwith one of the teeth to prevent reverse rotation of the member by the weight when said part moves due to loom stoppage.

4. In a loom having a part which moves when the loom stops and having a letofi mechanism provided with a member rotatable with the warp beam against the action of a weight as warp is consumed, the weight normally exerting a continuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprisinga series of ratchet teeth movable with the member, a set of pawls of different lengths normally disengaged from the teeth, and means connecting said part and the pawls to move the latter into engagement with the series of teeth and to place one of said pawls in holding relation with respect to one of the teeth to prevent reverse rotation of the member by the weight when said part moves due to loom stoppage.

5. Ina loom having a part which moves a given distance when the loom stops and having a let- 'oif mechanism provided with a member rotatable with the warp beam against the action of a weig t as warp is consumed, the weight normally exerting a continuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprising a lock for the member normally in nonlocking position and movable from normal position through a distance less than said given distance to locking position with respect to the member, connections between said part and the lock movable by the part when the latter moves due to loom stoppage to move the lock to locking position with respect to the member, and a yielding element in said connections which yields after the lock is in locking position to accommodate continued motion thereafter by the part.

6. In a loom having a part which moves a given distance when the loom stops and having a 1etoif mechanism provided with a member rotatable with the warp beam against the action of a weight as warp is consumed, the weight normally exerting a continuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprising a series of ratchet teeth secured to and movable with the member, a pawl normally disengaged from the teeth and movable into engaging, position relatively to the teeth, connections between the pawl and the part to move the pawl from normalpcsition to engaging position with respect to one of the teeth when said part moves clue tozloom stoppage prior to the completion of motion of said part through said distance, and a yielding element in the connections which yields after the pawl has engaged one of the teeth to accommodate continued motion thereafter of said part.

'7. In a loom having a part which moves when the loom stops and having a letoff mechanism providedwith a member rotatable with the warp beam against the action of a weight as warp is consumed, the weight normally exerting a con 1 tinuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprising an eccentric, a fixed pivotal mounting for the eccentric, a pawl pivoted on the eccentric, means operated by said part when the latter moves due to loom stoppage to turn the eccentric, means moving the pawl toward the member when the eccentric turns, and a series of ratchet teeth on the member to be engaged by the pawl to prevent reverse rotation of the plate by the weight, the eccentric turning when moved by the connections to said part in a direction to move the pawl bodily toward and into engagement with one of the ratchet teeth.-

' 8. In a loom having a part which moves when the loom stops and having a letoif mechanism provided with a member rotatable with the warp beam against the action of a weight as warp is consumed, the weight normally exerting a continuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprising a series of ratchet teeth moving with the member, an eccentric connected to said part to be turned by the latter when said part moves due to loom stoppage, a pawl pivoted on the eccentric, a stop moving with the eccentric normally holding the pawl out of engagement with the teeth of the ratchet, yielding means acting to move the pawl toward the teeth when the stop turns with the eccentric away from holding relation with respect to the pawl, said eccentric acting when turned by said part to move the pawl bodily toward and into engagement ith one of the teeth of the series.

9. In a loom having a part which moves when the loom stops and having a letoif mechanism provided with a member rotatable with the warp beam against the action of a Weight as warp is consumed, the weight normally exerting a continuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprising a series of ratchet teeth moving with the member, an eccentric connected to the part to be turned by the latter when the same moves due to loom stoppage, a pivotal support for the eccentric, the latter having narrow and wide parts on opposite sides of the pivotal support, a pawl pivotally mounted on the eccentric and normally held away from the series of teeth when the loom is running, means to move the pawl toward the teeth by a pivotal motion around the eccentric when the latter turns at the time of loom stoppage, the wide part of the eccentric moving toward a position between the pivotal support for the eccentric and the series of ratchet teeth when said part turns the eccentric to give the pawl a movement bodily in a direction from the pivotal support for the eccentric toward the series of teeth.

10. In a loom having a part which moves when the loom stops and having a letoff mechanism provided with a member rotatable with the warp beam against the action of a weight as warp is consumed, the weight normally exerting a continuous rearward force on the warp and cloth and tending to cause reverse rotation of the member and beam, that improvement comprising locking mechanism for the member normally in non-lockingrelation with respect to the member, and means controlled by the part when the latter moves due to loom stoppage to move the locking mechanism into locking relation with respect to the member to prevent reverse rotation of said member by the weight.

11. In a loomvhaving a part which moves a given distance when the loom stops and having a letoff mechanism provided with a member rotatable w-iththe warp beam against the action of a weight as warp is consumed, the weight normally exerting a continuous rearward force on the warp andlcloth and tending to cause reverse rotation of the member and beam, that improvement comprising a series of ratchet teeth secured to and movable with the member to any one of a plurality of difierent positions, a pawl normally disengaged from the teeth, an eccentric on which the. pawl is pivotally mounted, :a pivotal support for the eccentric, the latter having narrow and wide parts on opposite sides of the pivotal support, connections between the said part and the eccentric to move the Wide part of the eccentric toward a line joining the pivotal support and the ratchetteeth when said part moves at the time of loom stoppage, means to move the pawl against the ratchet when the eccentric is moved by said part, and a yielding element in said connections yieldingly transmitting, from said part to the eccentric a force which increases with increased yielding of said element and yielding when the pawl engagesa tooth before said part completes movement through said given distance, said element transmitting a considerable force from the partto be-exerted on the eccentric when the pawl engagesa ratchet tooth after a small amount of turning of the eccentric and the wide part of the eccentric has turned a small angular distance toward said line, and said element transmitting a smaller force from the part to the eccentric when the pawl engages a ratchet tooth after a larger amountof turning of the eccentric and the wide part of the eccentric has turned through a larger angular distance toward said line.

OSCAR V. PAYNE.

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