US2369536A - Warp tying machine - Google Patents

Description

Feb. 13, 1945. c. B. cmrinuJ.

wARP TYING MACHINE Filed Novl5, 1943 3 Sheets-Sheet l INVENTOR CI'B/ar/e s B. Cran'da/ fw. uw -M ATTORNEYS C,V B. CRANDALL.

WARP TYING MACHINE Feb. 13, 1945.

'5 Sheets-Sheet 5 Filed NOV. l5, 1943 INVENTOR Char/e5 Cra/vda 1"/ ATTORNEYS Patented Feb. 13, 1945 UNITED STATES PATENT OFFICE WARP TYING MACHINE poration of Illinois Application November 13, 1943, Serial No. 510,108

17 Claims.

The invention pertains to warp tying machines of the type disclosed in Colman Patent No. 1,442,776, dated January 16, 1923; and it has for a general object the provision'of an improved drive mechanism for the separator slide which operates to present to the tying mechanism the selected threads which are to be united.

Another object is to provide a warp tying machine having a drive mechanism for the separator slide 'embodying a connection releasable when the movement of the slide is interrupted upon failure of the thread selecting mechanism 'to function properly, and having combined therewith means operative as an incident to the disengagement of the driving connection to return the separator slide to its initial position. g

Still another object is to-prcvide for thel automatic reengagement of such releasable connection.

A further object is to provide for the disengagement of said releasable connection only at the time in the operating cycle when the thread selecting mechanism attempts and fails to select one or both of the two threads to be united, thereby preventing disengagement at other times when the load on the driving connection may be heavy.

The objects of the invention thus generally stated, together with other and ancillary advantages, are attained by the constructions and arrangement shown by way of illustration in the accompanying drawings forming a part hereof, in which:

- Figure 1 is a fragmentary side elevational view showing the knotter mechanism of awarp tying machine of the general character set 'forth in said Colman patent, the lower central portion of the frame being broken away toshow the improved drive mechanism for the separator slide, with the latter in its initial or retracted position.

Fig. 2 is a fragmentary vertical sectional View illustrating the operation of detecting failure of thread selection commonly known as stumbling, and as an incident thereto the blocking of the thread separator slide.

Fig. 3 is a fragmentary plan view of the separator slide.

Fig. 4 is a fragmentary elevational view on an enlarged scale showing the drive mechanism with its releasable connection, the parts of such connection being shown disengaged.

Fig. 5 is a similar view but showing the parts of the connection in normal or engaged relation.

Fig. 6 is a fragmentary elevational view looking to the left of 4 but on a reduced scale.

As set forth in said Colman patent, the warp 35 engage and hold such uniting mechanism is mounted upon a mechanism carriage l adapted to travel upon a bed, a portion of which is shown at 8. The mechanism acts upon two sets or sheets of threads or warps 5 a and b (Fig. 2), held in suitable clamps (not shown) mounted upon the bed of the machine. The carriage is fed along the bed in the well known manner as the operation of selecting and uniting threads from the two warps a and b 10 progresses. In the thread selecting operation, a

combined axial and swinging motion is imparted to each of two selectors 9 and 9' causing them to engage with the foremost threads of the respective warps and shift them toward each other preliminary to the advance of a separator slide I0 for the purpose of carrying the selected threads to a knetter II of conventional construction having a rotary tying bill I I' (Fig. 1).

The slide I8 is carried above and in spaced relation to a supporting bar Illa mounted for reciprocation relative to the carriage 1 'in any suitable or preferred manner. In the present instance powerv for actuating the knotter mechanism, including the slide l0, is derived from a hand crankl I2 (Fig. 1) forming part of a drive mechanism for the slide of improved construction, including a releasable connection generally designated I3.

The slide, which is disposed for reciprocation between the two warps` a. and b, comprises upper and lower separator plates I4 and I5. It carries two wings I6 and I1, one on each of the two plates It and I5, which wings are operative upon the separation of the threads from the two warps to threads in position for presentation to the knetter. Also mounted upon the Slide are two stumblers I8 and I9 pivoted at their rear ends on a crosspiece 20 and urged outwardly by a spring 20e.

40 The stumblers I8 and I9 are operative in a well known manner to block the forward movement of the slide in the event that either or both of the selectors 9 and 9' fail to select a thread or threads. As seen in Fig. 2, the manner in which the stumblers perform this function will be evident.

As here shown, the upper selector 9 has failed to seize and position its thread with the result that the upper Stumbler I8 has not been shifted downwardly by the selected thread and accordingly occupies a position such that in the advance of the slide the Stumbler engages a stationary abutment 2l. It will be observed that the lower stumbler I9 has been shifted upwardly out of the path of its abutment 22 as an incident to the selection of the thread by the selector 9', the movement of such thread by the selector against the stumbler shifting it out of alinement with the abutment 22.

It will be observed that lwhen either of the stumblers I9, I9 engages with its corresponding abutment 2| or 22 to interrupt the movement of the slide, the parts are brought to rest with a sudden stop and unless the drive mechanism is appropriately constructed, the shock is injurious not only to the mechanism but is objectionable particularly when the mechanism is operated by hand as by means of the hand crank I2. An important feature of the present invention resides in the provision of a slide driving mechanism which is simple, compact and practical, and which embodies a releasable connection operative to relieve such shock, capable ofA automatically reestablishing the connection and of preventing disconnection except during stumbling, and which is operable to restore the slide to initial retracted position in the event of a stumble.

Referring now to Fig. 1, the slide driving mechanism comprises a spur gear 23 rigid with the hand crank l2 and meshing with a gear 24 constituting a crank disk. The latter, in turn, is yieldably connected by means of a pitman 25 to a crank arm 26, through the medium of a block 26a slidable in a slot 2Gb with a spring 26c interposed between the block and the bottom of the slot so as to cushion the thrust of the pitman. The arm 26 is fast on a rockshaft 21 journaled in a bracket 28 on the base, and rotatably mounted on said shaft in spaced relation to the arm 26' is a slide driving member in the form of an arm 29 connected to the slide by means of a link 30. The crank arm 26 and the slide driving arm 29 are thus relatively rotatable. Accordingly, it is the primary function of the device I3 to provide a connection which is releasable automatically upon blocking of the slide by one or both of the stumblers.

The releasable connection I3 comprises a rocker drive member 3|, herein in the form of a thin generally segmental plate, and a dog 32 pivotally mounted on the arm 29 and normally held by a. spring 33 in engagement with a notch 34 in the free edge of the plate member 3|. The latter is mounted on the shaft 21 and is rigidly secured to the crank arm 26 but in axially spaced relation to the arm, both of the parts having hub portions` for spacing purposes and being rigidly connected together as by means of screws. The spring 33 is c'onnected at one end to the free end of the dog 32, and the other end of the spring is anchored to the slide driving arm 29. With the dog held by the spring in engagement with the notch 34 of the rocker drive member 3|, a driving connection is established between this member and the slide driving member.

In the operation of selecting threads and presenting them to the knotter mechanism. the slide I is moved forwardly from its outermost position as shown in Fig. 1, In this operation, the hand crank I2 is operated counterclockwise and the crank disk 24, rotating clockwise, imparts a forward thrust to the pitman 25, crank arm 26, rocker drive member 3|, dog 32, and slide driving member 29. In the event that the slide is interrupted in such forward movement by either or both of the stumblers I8 and I9, the dog 32 wil be forced out of its notch against the action of the spring 33 thereby disconnecting the slide from the actuating mechanism. It will be understood that the wall of the notch 34 which is engaged by the inner face of the nose of the dog is inclined sufciently relative to a radius of the member 3| passing through the notch to cause the dog to be forced out of the notch with a cam action when the force is sufficient to overcome the tension of the spring.

One of the functions performed by the slide in its forward movement is to actuate a shearing device 35 for severing the threads being acted upon. The shearing device, forming per se no part of the present invention, consists generally of coacting shear blades operated by means of a cam 35a rigid with the slide and enacting with a roller 35b of the shearing device.

It sometimes happens that an extra burden is placed upon the shearing device because of the improper selection of two threads by one selector instead of one and, in such event, a corresponding burden is imposed upon the releasable driving connection for the slide. On the other hand, if the releasable connection is to perform its intended function of avoiding shock and strain upon the parts and the operator. it is desirable that the tension of the spring 33 be relatively light so as to allow the dog to yield easily when the slide is blocked by one or both of the stumblers. To permit of easy release as an incident to the blocking of the slide by the stumblers while preventing such `release when a greater driving force is required, as when severing double threads, I provide detent means operative to hold the dog positively in driving engagement with the rocker drive plate 3| at all times except at the point in the cycle when the stumbling will occur if at all, this being in the present instance in the initial portion of the forward movement of the slide. l

Said detent means comprises, in the illustrative embodiment herein shown, a pivotal member 36 loose on the rockshaft 21 and disposed at one side `of the rocker drive plate 3|. The member has an upper end portion in the form of a hook 38a for coaction with a part on the dog 32, herein a pin 31 which forms an anchor for the upper end of the spring 33. The hook member also has a tail portion 38 for coaction with a stop 39 on the bracket 28. A spring 40 connected to the member 36 above the pivotal axis thereof tends to swing the hook 3'5 into engagement with the pin 31 (Fig. 5) and succeeds in doing so except in the approach of the slide to its outermost or retracted position when the member is interrupted by the engagement of the tail portion 38 with the stop 39. Upon such engagement, the pin 31 on the free end of the dog becomes disengaged from the hook and remains disengaged during the initial portion of the forward movement of the slide, this being the portion of the cycle when stumbling may occur.

In the event of failure of thread selection, with an ensuing interruption of the slide and release of the driving connection by disengagement of the dog 32, the operator continues to turn the hand crank so that the crank arm 26 and the rocker drive plate 3| rigid therewith continue in motion. moving first forwardly and then reversely. In this operation, the nose of the dog is slidably supported upon an upper arcuate surface 4I on the free edge of the plate which is of a length somewhat in excess of the length of the arc through which the plate is turned by the crank disk 24 so that the dog is continuously supported by the plate. Finally, as the plate is returned by the crank disk toward its initial position, the notch 34 is carried into position to receive the dog, thereby automatically reestablishins the connection for the succeeding cycle. To limit movement of the dog by frictional engagement with the moving plate 3| too far for reengagement with the notch 34 at the end of the return stroke, an adjustable stop screw 4Ia is mounted on the drive arm 29 for engagement with a part of the frame.

Failure of thread selection usually occurs in any given cycle in the case of only one of the warps. It is therefore necessary that theathread which has been selected in such cycle be positioned for reselection in the succeeding cycle. If it were permitted to remain in selected position another thread might in the succeeding cycle be 'selected from the same Warp so that doubles ment, I utilize the continued forward movement of the plate 3| which occurs as above indicated upon disengagement of the dog 32. Accordingly, the plate 3| is provided on one side thereof with a cam 42 for coaction with a slide return member 43 equipped with a roller 44 for coaction with the cam.

The member 43 is in the nature of a bell crank lever pivoted at 45 upon a standard 46 rising from the base of the bracket 28. Said lever has summarizing the operation, at the beginning of a cycle, the parts occupy the relation shown in Fig. 1 with the separator slide II) retracted. The hand crank I2 is rotated in a counterclockwise direction turning the crank disk 24 clockwise and imparting a, forward thrust (to the left,

Fig. 1) to the pitman 25.- The thrust of the pitman upon the crank arm 26, cushioned by the spring 26, results in rocking of the crank arm to the left and with .it the segmental rocker drive plate 3|.

In the normal operation, the motion thus imparted to the plate 3| is transmitted to the drive arm 29 through dog 32 engaging notch 34 in the periphery of the plate 3|, the arm 29 causing the slide to move forwardly by reasonfof its connection by link 30 to the separator slide. At the same time, the slide restoring lever 48 moves forwardly, the pin moving clear of the slot 49 and the roller follower 44 passing downwardly in front of the cam 42, coming to rest on the arcuate surface 44a.

one arm 4'I carryingthe roller follower 44 and another arm 48 with a projecting finger 49 for engagement by a pin 5|! on the slide driving arm, said pin constituting the pivotal support for the dog 32. Adjacent the finger the arm 48 is formed with an open ended slot 5I, one wall of which is formed by the finger 49. This slot is adapted to receive the -pin 50 for the purpose of providing a connection between the bell crank lever and the slide driving arm 29 when theflever is swung .upwardly by the cam 42 in a manner presently described.

During the latter part of the retracting movement of the slide driving arm upon completion of one cycle, the pin 50 engages the nger 49 on the f bell cranklever 43 swinging such lever so as to shift the roller follower 44 upwardly into position for cooperation withthe cam 42. Assuming that initial partial advance of the slide, the roller 44 on the lever is held by the pin 50 and notch 5| in position to be engaged by the cam 42 in the continued movement of the plate. In this operation, a cam surface 52 on the forward end of the cam 42 imparts a swinging motion to the lever in a, clockwise direction, as shown in Fig. 4, and since at this time the pin 50 is engaged in the slot 5I, the motion imparted to the lever is transmitted to the slide driving arm. The result is that the slide is restored to its initial position' and the selected thread released from the corresponding separator wing.

Ill

blers so that the arm 29 comes to a stop after an y In the event that either of the selectors 9 and 9' fails properly to select and position a thread, such failure is detected by the corresponding Stumbler I8 or I9 since the selected thread, being held relatively taut as it is moved toward the Stumbler, normally operates to swing the Stumbler into an inoperative position.- When not thus positioned by a selected thread, the Stumbler remains in a position such that after the initial portion of the advancing movement of the slide such movement is interrupted by the engagement of the Stumbler with one of the stationary members 2| or 22.

.The blocking of the slide in the manner thus` set .forth occurs, if at all, at the beginning of a cycle or shortly after the slide has started forwardly. In this position of the parts, the locking hook 36a occupies a position (Fig. 1) -clear of the pin 31 on the dog 32 so that the nose of the dog is free to ride out of its notch in the plate 3| when the force exerted on the plate is sufflcient to overcome the tension of the spring 33. Upon such release, the plate 3| continues to move forwardly with the nose of the dog riding upon the upper arcuate edge of the plate.

Upon reversal of the plate due to the continued motion of the hand crank, the connection between the arms 29 and 26 is reestablished by the entry of the dog 32 into its notch 34 under the action of the spring 33; and in the latter portion of the return movement of the slide, the tail 38 of the locking hook engages with a stop, thereby interrupting the movement of the tail which normally moves with the drive arm by reason of the spring connection 40. As a result, the pin 31 moves clear of the hook so that in the initial portion of the succeeding cycle, the dog 32 is free to move into disengaging relation to the plate. y

In the movement of the slide into its retracted position, the pin 50 on the drive arm engages with the finger 49 on the bell crank lever 43 and shifts the lever to position the roller follower 44 upwardly in the path of movement of the cam surface 52 on the cam 42. In, therefore, a stumble should occur at the beginning of the succeeding cycle, the dog 32 will yield against the action of the spring 33 disconnecting the driving plate 3| from the drive arm and carrying the cam' 42 with its surface 52 into engagement with the roller 44. Thus, while the drive plate continues to move forwardly while the slide remains blocked by one of the stumblers,

y point in the the lever 43 is swung counterclockwise and through its connection 48, 49 with the drive arm restores the slide to its initial position. The slide is thus retracted to carry the wings IB, I1 free of any thread which may have been selected in such cycle, for reselection in the succeeding cycle.

It will be seen that by the construction provided, the various contingencies incident to the operation of the separator slide are effectually taken care of. When stumbling occurs in one cycle as result of failure of thread selection, the driving connection is not only released to avoid strain and shock upon the parts and the operator, but it is automatically reestablished at the end of the cycle to recondition the parts for the succeeding cycle. By permitting the release of the driving connection only during that part of the cycle during which the slide may be blocked as a result of improper thread selection, it is possible to reduce the shock -and strain by decreasing the amount of spring tension which must be overcome to release the connection. At the same time it insures that disconnection will not occur when it is undesirable as when the slide operated shearing device is subjected to an unusually heavy load. Also, it will be observed that upon interruption of the slide, due to stumbling, and a consequent release of the driving connection, the slide is shifted to its initial position as an incident to the continued operation oi the actuating mechanism, thereby restoring the previously selected thread or threads into position for selection in the normal way.

A feature of substantial importance is the accomplishment of these various functions by means of a small, compact, unitary structure occopying e. relatively small amount of space so as' to be capable of being mounted in an out-oi-the-I way position on the knotter carriage.

I claim as my invention:

l. In a warp tying machine, the combination a knetter mechanism comprising a knetter, thread selecting means, a reciprocatory slide operative to present selected threads to the knetter, Stumbler means operative upon failure of thread selection to interrupt movement of the slide, and a drive mechanism for the slide including a rocker drive member, a slide driving member mounted to turn on the axis of the rocker member, and means providing a releasable connection between mid two members operative to disconnect the members when said slide is interrupted.

2. 'in a warp tying machine, the combination oi a knotter, means for supporting two warps, Imeans for selecting a pair of threads, one from each of said warps, a reciprocatory separator mide .for presenting selected threads to said knotr, a drive mechanism .for imparting one commete reciprocation to said slide for each tying cycley and means operative as an incident to iailure of thread selection to interrupt the movement of the slide, said drive mechanism including 4two members yieldably connected together for movement in unison in a normal cycle but relatively movable upon interruption of the movement of the slide, and operative positively to prevent yielding ci said connection, the last mentioned -means being inoperative at the cycle at which said slide is intorrupted upon failure of thread selection.

3. A warp tying machine having, in combination with a knetter, thread selecting means sind a slide for presenting selected threads to the im; tter, a drive mechanism for reciprocating 'aile oli slide comprising a rocher drive member, a second member operatively connected with said slide, said two members being mounted to turn on a common axis, a dog pivoted to one member and yieldably held in driving engagement with the other member, a hook normally connected to move with said members and acting to hold said dog against yielding movement, and -means operative at a predetermined point in the movement of the slide to disengage said hook Jfrom said doe'.

4. In a watp tying machine having a supporting irame and a thread positioning slide mounted for reciprocation on said frame, a drive mechanism for reciprocating said slide once in each operating cycle, comprising an arm pivotally mounted on said frame and operatively connected with said slide, a rocker drive member mounted to turn on the axis of said arm, and a releasable connection between said arm and said meinber including a dog mounted on the arm and spring-pressed into driving engagement with said member, said dog being adapted to yield relative to said member to release said connection upon an interruption of the movement oi the slide, and means operative positively to prevent yielding of said dog except upon interruption of the movement of the slide at a predetermined point in such cycle.

5. A warp tying machine having, in combination with a knotter, thread selecting means and a slide :for presenting selected threads to the knotter, a drive mechanism for reciprocating the slide comprising a rocker drive member and a slide driving member mounted to turn on a common airis, a dog pivoted to one member, the other one oi said members having a notch iorreceiving the dog and an arcuate surface at one side of said notch, a spring acting upon said dog to hold it in said notch and yieldable upon interruption of the movement of the slide driving member to permit continued movement of the inciter drive member, said arcuate surface slidein; supporting said dog ior reengagement thereoi' with said notch upon a reverse movement oi the rocker drive member, a detent normally movable with said two members and acting to hold said dog in said notch, and means operative at a predetermined point in the moveit oi the slide to disengage said detent from ro for rcciprocation on said frame, a drive mechanism ior reciprocating said slide comprising an arm. pivotally mounted on said frame and operatively connected with said slide, a rocker drive member mounted to turn on the axis oi said arm, and a releasable connection between said arm and said member including a dog mounted on 'the arm and spring-pressed into driving engagement with said member, said dog being adapted to yield relative to said member to release said connection upon-an interruption of the movement oi the slide.

'7. in a warp tying machine having a supporting frame and a thread positioning slide mounted for reciprocation on said frame, a drive mechanism for reciprocating said slide comprising a slide drive member pivotally mounted on said. frame and operatively connected with said slide. a rocker drive member mounted to' turn on the axis of said arm, and a releasable connection between said members including a dog mounted on one member and spring-pressed into driving engagement with the other member, the last mentioned' member having Va notch in one ledge Iinjwhich lsaid dog is yieldably held when the connection "is established, and means supporting the dog `when released land `operative .in the Vre- -ciprocation of the member to reestablish such l `connection automatically.

8. .YA warp 'ftying machine having, .in combinattion with a lmotter, thread selecting Ameans and la 'slide for Apresenting lselected 'threads to ythe knotter, .a kdrive :mechanism for k:reciprocating the slide V"comprising "a rocker fdrive member land a @slide driving member mounted to turn .on ay comy fmon axis, a `dog ,p'ivoted to :one member, 4the other 'one-of said-members having Aa notch for ate surface-slidably `.supporting said dog :for reengagement thereof ywith'saiclnotch upon a re- Averse movement of therocker drive member.

9. vAwarp tying y'machine having, in combina- -tion with2aknotter, threadselecting means and knotter, a drive mechanism Vfor vreciprocating Vthe slide comprising va rocker drive member and la slide 'driving member mounted to turnon a common axis, adog pivoted to one member, the other 'one of saidzmexnbers having a notch for receiving the dog andan arcuate surfacefat one side of said notch, .a spring acting upon `said dog to vhold it in saidnotch and yieldable upon interruptionof'theimovement .of the slide driving rmember topermiticontinued movement of the rockerdrive member, .and cam means operative in'such continued movement of the rocker drive member independently ofthe slide drivingmember .to impart areverse movement tothe slide driving member.

a slide for presenting Aselected threads to the 10. `In a warp tyingmachine the combination of a knotterfzmeans for supporting two warps, means vfor selecting'a pair of threads, one from each of said y'warps,v ai reciprocatory separator device for presentingselected threads to said knotter, a drive .mechanism for imparting one complete reciprocation to said device for each tying cycle, and means operative upon failure of'thread selection 'and at a kpredetermined point in each cycle to interrupt themovement of the separator device, said driving mechanism including two members lyieldably connected together for movement inunison in a normal cycle but arranged for relative movement upon interruption of the movement of said device, and means operative by one of saidmembers inits movement relative tothe other fmember to impart a reverse move- .mentito 'said device.

11. Ina warp .tying machine having la supporting frame, a threadpositioning slide mount- -ed forfreciprocation on Asaid frame, a drive mechanism for reciprocatingy said slide *comprising a vslide ydriving memberpivotally mountedl on said lframe, Aa rocker drive member mounted Ito turn Yon. vthe axis of'said slide driving fmember, a releasable connection' between' said' members operment to the separator slide.

vlain'awarp tying machine, the combination of a knotter mechanism comprising thread selectors, va reciprocatory slide having means for positioning the selected threads upon withdrawal of the selectors, stumbler means operative upon failure of thread selection to interrupt movement ofthe slide, a drive mechanism including two members having a yieldable connection releasable for relative movement upon interruption of the slide, and cam means operative as an in- --cident to such relative movement between the members to impart a retracting movement to the slide whereby to restore the selected threads to a position for reselection in the succeeding cycle.

13. In a warp tying machine, the combination of a knotter mechanism comprising thread selecting means, a vreciprocatory slide operative to 'present selected threads to the knotter mechanism, stumbler means operative upon failure of thread selection to interrupt movement of the slide, a drive mechanism including two members having a yieldable connection therebetween, said rrocker drive mechanism being adapted for continued movement upon interruption of the slide,

a lever operatively connected with said slide driving member when the movement of the slide is interrupted, and a cam rigid with the rocker drive member and operative in the continued movement thereof to actuate said lever so as to yimpart a restoring movement to Isaid slide.

14. In a warp tying machine, the combination of a knotter mechanism comprising a knotter, thread selecting means, a reciprocatory slide operative to present selected threads to the knotter, Stumbler means acting upon failure of thread selection to 'interrupt movement of the slide, a drive mechanism for the slide including a drive member and a slide driving member adapted for relative movement upon such interruption of the slide by said stumbler means, said drive mechanism being operative to impart one complete reciprocation to said silde for each knot tying cycle, a lever, means operative in the movement of the slide to its'initial or retracted position to establish a driving connection between said lever and said slide driving arm, and cam means operative as an incident'to relative movement between said members upon interruption of the slide by the stumble'r'means to restore the slide to such initial position.

15. In a Warp tying machine, a knotter mechanism comprising a knotter, thread selecting means, a reciprocatory slide for presenting selected threads to the knotter, stumbler means operative upon failure of thread selection to interrupt movement of the slide in the initial portion of such movement toward the knotter, and a drive mechanism for the slide including a drive member and a slide driving member mounted to turn 0n a common axis, means providing a disengageable driving connection between said two members releasable upon such interruption of the movement of the slide, a lever having a roller follower, a cam rigid with said drive member and operative upon said lever through said follower to impart a shifting movement to said 1ever in a direction opposite that of the drive member following release of such connection, and means operative in the movement of the slide to its retracted position in a normal operating cycle .to establish a driving connection between said lever and said slide driving member.

16. In a warp tying machine, the combination of a knotter mechanism comprising a knotter, thread selecting means, a reciprocatory slide operative to present selected threads to the knotter, stumbler means acting upon failure of thread selection to interrupt movement of the slide, a drive mechanism for the slide including a drive member and a slide driving member mounted to turn on a common axis, means providing a releasable connection between said two members, said drive mechanism being operative to impart a complete reciprocation to said slide in a normal knot tying cycle, and said connection being releasable in response to blocking of the slide by said Stumbler means, and means for restoring the slide to its initial position upon release of said connection, said means including a lever having a cam follower and a cam on said dri-ye member for coaction with said follower to impart a reverse shifting movement thereto in the movement of said drive member following such disconnection, said lever being shifted in the return movement of the 'slide in the normal cycle to establish a connection between the lever and said slide driving member and to position said follower relative to said cam.

' porting frame, a thread positioning slide mountlil ed for reciprocation'on said frame, a drive mechanism for reciprocating said slide including an actuating member and a driven member, a disengageable connection between said members releasable upon blocking of the slide at a predetermined point in the movement thereof whereby to permitfcontinued movement of the actuating member, and means operative upon such interruption of the slide to impart a reverse restoring movement thereto, said means including a cam rigid with the actuating member, a lever having a follower for coaction with said cam, and means operative upon the return of the slide to its initial position in the normal operating cycle to position said follower relative 20 out of the path of said cam.

CHARLES B. CRANDALL.

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