US1925513A - Shoe sewing machine - Google Patents

Description

p 1933- F. ASHWORTH SHOE SEWING MACHINE Filed March 11, 1932 4 Sheets-Sheet 1 Sept. 5, 1933. F. ASHWORTH SHOE SEWING MACHINE Filed March 11, 1932 4 Sheets-Sheet 2 k QM/QM V Sept. 5, 1933. F, ASHWORTH snom sswme momma Filed March 11, 1952 4 Sheets-Sheet 5 JOZ Sept. 5, 1933. F. ASHWORTH 1,925,513

' SHOE SEWING MACHINE Filed March 11, 1932 4 Sheets-Sheet 4 Patented Sept. 5, 1933 SHOE SEWING MACHINE Fred Ashworth, Wenham,

Mass, assignor to United Shoe Machinery Corporation, Paterson, N. J., a corporation of New Jersey Application March 11, 1932. Serial No. 598,213

11 Claims.

The present invention relates to shoe sewin machines'and is intended primarily as an improvement in lockstitch shoe sewing machines of the so-called McKay type which comprise a straight hook needle, a shuttle, a rotary shoe supporting horn arranged to extend inside of the shoe, a needle threading whirl located in the horn, and devices for controlling the thread as it is delivered to the whirl in the horn.-

The object of the invention is to provide a lockstitch shoe sewing machine of the McKay type which is adapted for sewing materials or" both ordinary and unusually great thicknesses where the variation of thicknesses are greater than with ordinary work of uniform thickness.

The several features of the invention are herein illustrated as embodied in a sewing machine which is intended as an improvement on the machine disclosed in my prior applications for Sewing machines, Serial No. 394,770, filed September 24, 1929, Serial No. 418,545, filed January 4, 1930 patented August 30, 1932, No. 1,874,690 and in the application for Sewing machines of Bernard T. Leveque, Serial No. 169,203, filed February 18, 1927 patented November 1, 1932, No. 1,885,927. In the machine disclosed in these applications, springs are provided for forcing the presser foot against the work to retain the work in place on the horn during the sewing operation. However,

the resistance to movement of the needle in the i work may be so great, when unusually thick materials are being operated upon, as to cause the presser foot to be lifted against the action of the springs when the threaded needle is being retracted through the work. According to a feature of the present invention, locking devices are provided, which while preventing lifting movement of the presser foot while the needle engages the work, are arranged to be intermittently released in order that the presser foot may be lifted as the work is being fed and also to be released when the machine is brought to rest at the end of the seam. In the machine disclosed in the applications above referred to, mechanism is provided for bringing the machine to rest at the end of a seam with the needle and presser foot disengaged from the work. In embodying the above feature of the invention in this machine, the locking devices for the presser foot are actuated by a lever connected to oscillate with the movements of the needle, so that the presser foot may always be released from the locking devices when the machine is brought- F to rest according to the ordinary operation of the resistance to the passage of the needle and also is provided with a hand lever for manually lifting the presser foot, and in the illustrated embodiment of the present invention, a connection from this lever is arranged to release the locking devices for the presser foot, in order that the. presser foot may be lifted regardless of the position of the needle with respect to the work.

The mechanism of the machine disclosed in the applications above referred to for disengaging the presser foot at the end of a seam also acts when thrown into operation to release the thread from a sewing thread lock against which the stitches are set, so that the work may be drawn away from the horn before cutting the thread. The connections between the presser foot lifting mechanism, the presser foot and the thread lock in'this machine are such that if the presser foot is adjusted to operate properly on thin work, the thread lock is likely to be held when thick work is being sewn on account of the elevated position of the presser foot on the thick work. A feature of the present invention, therefore, contemplates an arrangement of these connections in which the presser foot will not actuate the I thread lock when lifted by thick work from a position which it normally assumes on this work, but the presser foot may be lifted, and the thread lock opened when the normally inoperative mechanism is thrown into operation at the end of a seam. As a result of the arrangement of the connections according to the present invention, the manually operated presser foot lifting lever may be actuated to lift the presser foot at any time without affecting the condition of the thread lock.

In addition to the features of invention above referred to, the present invention also consists in the combinations, devices and arrangements of parts hereinafter described and claimed the advantages of which will be obvious to those skilled in the art.

Referring to the drawings, Fig. 1 is a view in side elevation of a lockstitch shoe sewing machine embodying the features of the present invention; Fig. 2 is a view in front elevation on an enlarged scale of the sewing head of the machine, indicating its relation to the material being operated upon; Fig. 3 is a view in side elevation of a portion of the mechanism in the head of the machine illustrated in Fig. 2, looking from the right hand side; Fig.4 is an enlarged sectional view taken along the line 4 of Fig. 3; Fig. 5 is asimilar view of the same mechanism shown in Fig. 4 with the parts in a slightly diflerent relation; Fig. 6 is a detailview in side elevation of a part of the locking devices for the presser foot; Fig. 7 is a View in vertical section of a part of the mechanism in the head of the machine, looking from the front; Fig. 8 is a View in side elevation of a portion of the mechanism shown in Fig. 7, looking from the left; Fig. 9 is a view of a portion of the mechanism for actuating the thread tension and thread lock for releasing the thread; and Fig. 10 is a view in side elevation of the same mechanism.

Except as hereinafter described, the machine illustrated in the drawings is the same in the construction, arrangement and mode of opera-' tion of its various parts as the machine disclosed in my prior application Serial No. 394,770, hereinbefore referred to. The machine comprises a column 2 in the lower part of which is mounted an electric motor l by which the operating parts of the machine are drive; The main sewing cam shaft is indicated at 6 and is journalled in the sewing head mounted on the column." The .shaft 6 isdriven from the motor 4 through a clutch 8, horizontal shafts l0 and 12 in the base of the machine, anda verticalshaft i l The clutch 8 is controlled from a treadle 16 by means of which the clutch maybe actuated to connect and disconnect the shafts 10 and 12 from the motor 4, The shoe supporting horn is indicated at 18 and is provided in its tip with a whirl of usual construction which is driven through suitable connections from the verticalshait these connections being the same as those disclose in my applications above identified. The stitchforming devices including the straight hook needle, indicated at 22, and the shuttle 24 are actuated from the sewing shaft 6 in the same manner as in my prior macl he. The connections between the sewing shaft e d the needle comprise a crank pin 26 upon the forward end of the sewing a slotted lever 28 engaged .by the pin,-a needle actuating lever 30, a latch on connecting the slotted lever and the needle actuating lever and a link 34 connecting the needle actuating lever to the needle bar 36. The shuttle is driven from the needle actuating lever through a link 38 which connects a downward extension from thehub of the lever to an upwardly extending of the shuttle actuating gear segment 40. This segment meshes with a pinion 42 mounted upon one end of the shaft which drives the shuttle. By actuating the connection latch 32, the needle actuating lever 30 can be disconnected fromthe sewing shaft 6 when the needle is disengaged from the work and has reached its highest raised position and while the shuttle is at one limit of its movement. The latch 32is actuated from the starting and stopping treadle 16 upon movement of the treadle to disconnect the driving motor 4 from the machine, in the sarnemanner as in the machine cf the prior applications above referred to.

The connections from the stopping and starting treadle 16 for actuating the latch 32 to disconnect the needle actuating lever 30 from the and connected at its forward end .by a link at to operate a'rock shaft 56 upon the forward end of which an upwardly extending needle locking lever 58 is secured. A heavy coiled spring (not shownlsurrounds the shaft, 48 and tends to l ll vit he el ckwi d res en- W l t machine is running, the treadle 16 is depressed and the lug 50 is held out of engagement with the arm 52. Upon release of the treadle, the clutch 8 is first operated to disconnect the motor 4 from the machine and the arm it swings upwardly, then causes the lug so to engage the rearward extension of the arm 52. Thereafter, the coiled spring acting through the arm d5 turns the arm 52 yieldingly in a clockwise direction and through the connections to the locking lever 58 moves the lever in a counter-clockwise direction to disengage the latch 32 from. the lever 30 and lock the needle at the upper limit of its stroke.

The presser foot, indicated at 60, is secured to a clock 62 attached to the lower end of a vertically movable presser foot bar 64. The presser foot is forced downwardly against the work bymeans of a spring 66 surrounding the presser foot bar, and also by a spring 68 which surrounds the shaft to and secured at one end to a collar 72 fast on the shaft, and at its other end to a collar 74 adjustably secured to the machine frame. The spring 68 operates to rotate the shaftin a clockwise direction, and the shaft carries an arm 76 fixed to its forward end, which arm connected to the presser foot block 62 by a pin and slot connection, the construction being the same in the machine of my prior anpl cation, Serial No. 39 5770.

The work is fed durin g each stitch-forming cycle of operation of the machine by a feed point 78, and in order to per lit the feeding movement,

the presser foot intermittently lifted from en-, with the work, as in the machine of my prior application, Ser. No. 39%,770, by mech a sm which comprises a cam lever 80 loosely fulc on a shaft 82, which lever carries a cam rolls-i adapted to ride on a cam 86 on the sewing shaft 6 of machine, an arm 88 connected to 1 lever 8% by a link 90, a shaft 92 and devices connected between the shaft 92 and the presser foot bar 64 for lifting the presser foot bar a uniform amount. upon each oscillation of the shaft.

foot and the horn and while the presser foot is being raised by the cam lever 80. If the work is of unusual thickness, a large amount of resistance is offered to the passage of the needle loop through the work as the needle is retracted. This resistance may be sufficient in the machine of the prior applications, to overcome the action of the springs 66 and 68 and raise the presser foot 60.

According to the pr sent invention, while the needle is being retracted through the work, the presser foot is held against movement by locking devices comprising a plurality of pawls d engaging a toothed segment 96 attached to the right hand of the presser foot arm 76. The pawls 9 1 are of slightly different length in order to engage a single tooth on the segment 96 in sligh ly different positions of the arm 76 and are pivotally mounted upon a sleeve 97. The sleeve is rotatable upon the reduced portion of a screw 98 threaded adjacent its headed end into an arm of a bracket 99 attached to the frame of the. machine.

The other end of the screw fits within an 1 opening in the main body of the bracket 99 to form a firm support for the pawls. The pawls are pressed into engagement with the segment 96 by a series of springs 100, there being one spring for each pawl and each spring being held within a corresponding hole formed in a lever 102 in a position to act against a shoulder portion of each pawl 94. The lever 102 is forked and surrounds the pawls 94 adjacent the sleeve 97 on which the lever 102 is also fulcrumed. The lever 102 is normally held in a position to cause the pawls 94 to engage the segment 96 by a spring 104 secured at one end to an upwardly extending arm of the lever and at its other end to a pin 105 secured in the bracket 99. When the lever 102 is moved against the action of the spring 104, a boss formed on the upper arm of the lever is caused to engage a series of arms extending upwardly, one,

from each of the pawls 94, so as to cause the pawls to be disengaged from the segment 96. The action of the spring 104 is limited in drawing the lever in a direction to engage the pawls 94 with the toothed segment by an adjustable set screw 106 passing through the bracket 99.

To intermittently release the presser foot from the locking action of the pawls 94 so that the presser foot may be lifted and the work fed, the lever 102 is provided with a horizontally extending arm formed with a cam surface arranged to cooperate with a roll 108 mounted at the upper end of an arm 110 fixed to a short shaft 112 loosely fulcrumed in a portion of the bracket 99. The shaft 112 is rocked to intermittently retract the pawls 94 from the segment 96 through the movement of the roll 108 along the lever 102 by an upwardly extending slotted arm 114 also secured to the shaft with its upper slotted end engaging a roll 116 carried by a bolt 118 projecting from the downwardly extending arm of the needle actuating lever 30 which also actuates the shuttle. The arrangement is such that as the needle engages the work the pawls 94 will be brought into engagement with the segment 96 to lock the presser foot against movement and as the needle reaches the upper portion of its stroke after disen agement with the work, the presser foot will be released from the locking devices to permit 7 the presser foot to be lifted while the work is being fed. 1

In order to permit the presser foot to be raised by the operator at any time regardless of the position of the needle the usual hand lever, indicated at 120, is provided with a pin 122 for-engaging the upwardly extending arm of the pawl actuating lever 102 when the lever 12.0 is operated to raise the presser foot, the manner described in my prior application. The pin 122 rst strikes the lever 102 and releases the pawls 94 from engagement with the segment 96 and thereafter, upon continued movement the hand lever acts against a pin 123 on the presser foot bar to raise the presser foot. For convenience in construction, the spring for returning the hand lever 120 to inoperative position, indicated at 124, is attached to the pin 122 at one end and at the other end to the pin 105 to which the spring 104 is secured.

As stated, a feature of the present invention consists in the arrangement of certain connections for lifting the presser foot and releasing the thread from the thread lock in order to prevent movement of the presser foot from eifecting the stitch-setting operation. The machine of prior application is provided with normally inoperative mechanism for raising the presser foot clear of the work atthe *endof upper ends on the sewing shaft 6.

ing operation after the clutch 8 has been etctuated to disengage the driving motor 4 from gage-the roll 154 at the right hand end of an Since the retract-ing member is not moved a seam to permit removal of the work. This mechanism acts directly on the shaft '70 to which the presser foot lever 76 is attached. According to the present invention, a separate lever 126 is loosely mounted on the shaft 70 near? 80 its inner end. The lever 126 is formed at one end with a T-shaped lug 128 to be operated upon by a hook-shaped retracting member 130 and a retaining member 132, hung from their The re- 35 tracting member 130 is suspended from an eccentric 134 carried by the sewing shaft 6 and the retaining member 132 is mounted loosely upon the shaft itself. At the end of the sew the machine, the shaft 56 is rocked by connections to the foot treadle 16, in the manner described above. Movement of the shaft 56 causes the retracting and retaining members 130 and- 132, respectively, to be brought into engagement with the T-shaped lug 128 by movement of an arm 136 secured to the shaft 56 and a pair of compression springs 138 and 140 surrounding respectively, links 142 and 144. The link 144 is pivoted at one end to the retracting member 130 and at the other end slides loosely through a pin 146 mounted in the lower end of the arm 136. 'The link 142 is pivotally con- 4 nected to the lower end of the retaining mem- 39 her 132 and at the other end slides loosely through another spring in the pin 146 so that, as the arm 136 moves in a counter-clockwise direction after the motor has been disconnected from the machine, the members 130 and 132 are 5-139 yieidingly brought into engagement with the lug 128 and, as the sewing shaft 6 continues to rotate, the lug 128 on the arm 126 is raised by the retractingmember and held by the retaining member in raised position. Upward movement of the lug 128 causes the opposite end of the lever 126 to engage a projection 148 extending from an arm 150 attached to the shaft 70. Further movement of the lever 126 thereafter causes the shaft '70 to be rocked in a counterclockwise direction, raising the presser foot arm '75 and moving the presser foot 60 upwardly away from the work.

The presser foot will always be released from the locking action of the pawls 94 in time to permit the presser foot to be raised when the normally inoperative lever 126 is actuated. This sequence is obtained by reason of the connections between the arm 46 on the treadle operated shaft 48 and the needle locking lever 58, and by reason of the construction of the locking lever. During the sewing operation, a roll 154 fixed to one end of the needle actuating lever 30 travels up and down against the left hand side of a slot 156 in the locking lever 58. As soon as the treadle is released, the connections between the treadle and the lever58, including a spring 158, act to cause the locking lever 58 to engage the roll 154 under the influence of the spring, on the right hand side of the slot 156 without appreciably moving the lever 58.- However, as soon as the needle reaches the upper limit of its stroke, the locking lever 58 is moved in a counter-clockwise direction by the spring 158 to enthe same time disconnecting-the needle actuating lever 80from the crank actuated lever 28.

' into operative position until the spring 158 is allowed to rock the shaft 56 which carries the locking lever 58 and the arm 136, no movement will be imparted to the presser foot until the needle hasheen locked in raised position and the pawls 94, therefore, disengaged from the presser foot arm 76.

Connections are also provided for operating the thread lock in the base of the horn. to release the thread at the end of a scam in order that the work may be removed from the horn. These connections comprise an arm 160 pivoted on a bolt 162 secured in the head of the machine, an adjustable set screw 16% passing vertically through the arm 166 and engaging an enlargement at the end of the lever 126, a link 166 connected at its upper end to the arm 160 and at its lower end to a lever 168 fulcrumed intermediate its length on a bolt 170 threaded into the column 2 of the machine, and an arm of the lever 168 extending forwardly to engage and operate the thread lock. In the present embodiment of the invention, a dry thread tension 172 is employed and the thread lock is of the same construction as describec the Leveque app ication. This lock, indicated at 174, acts to grip the thread while the stitches are being set and is opened to release the thread during each stitch-forming cycle so that a supply of thread may be drawn for each succeeding stitch through the tension 172.

To operate the thread lock 1% to release the thread during each stitch-forming cycle, a shaft 176 on which the thread lock is mounted is arranged to he oscillated and reciprocated against the action of a spring 1'78 surrounding the shaft, by a lever 180 mounted on the inner end of the shaft. Dne end of the lever carries a cam roll 82 cooperating with a cam 184 attached to a shaft 186 which forms a part of the driving connections between the vertical shaft lei and the needle threading whirl in the horn. The other arm of the lever 186 engages the upper surface of the lever 168, so that as the lever 168 is rocked, the roll 182 on the lever 180 is disengaged from the cam 15% and the thread lock is operated to release the thread.

In order to insure that the normally inoperative lever 126 may be maintained in a proper position, the arm 150 carries a slidable pin 190 resiliently engaging the outer end of the lever 126. The pin 1% forces the enlargement on the lever 1.26 into engagement with the set screw 164 by a spring 192 on the pin 1% compressed between the arm 150 and a shoulder at the lower end of the pin. The arm 160.carrying the set screw 16 i is maintained in a raised position against the action of the spring 192 by a tension spring 19-1 acting be tween the lever 16S and the frame of the machine which spring, being stronger than the spring 192, prevents improper operation of the thread look by movement of the arm 150. The forward arm of the lever 158 carries an adjustable set screw 196 which, while the machine is running, limits the movement of the lever 168 by acting against a portion 198 of the machine frame to hold the lever 168 and the lever 126 of the normally inoperative mechanism in fixed position through the connections just described.

By the connections, as thus arranged, a lifting movement of the presser foot during operation of the machine causes the projection 148 of the arm 150 to be moved away from the lever 126 (see 2) without affecting the operation of the needle thread lock. Operation of the lever 126 to release the thread lock, in the manner described, at the end of the seam, also causes the presser foot to be raised regardless of the adjustment of the presser foot lifting connections. Also, the presser foot may be manually unlocked and raised at any time without disturbing the operation of the thread lock.

Having thus specifically described a machine embodying the several features of the invention, and the nature and scope of the invention having .been indicated, what is particularly claimed is:

1. A sewing machine having, in combination, stitch-forming devices including a straight hook needle, a sewing shaft, means for driving the sewing shaft, a rotary work supporting horn and a presser foot, a resilient member for forcing the presscr feet against the work, means actuated from the sewing shaft for intermittently lifting the presser foot to permit the work to be fed, a power 0 erated presser foot iii" ing mechanism normally inoperative during operation of the machine and thrown into operation after the sewing shaft is disconnected from the driving means to lift the presser feet, a locking device for preventmove out of the presser foot against the action of e resilient member while the needle engages the work, and mechanism under the control of the operator for disconnecting the sewing shaft from the driving :zneans and for rendering the locking device inoperative.

2. A sewing machine having, in combination, stitch-forming devices including a straight hook needle, sewing shaft, needle actuating connections between the sewing shaft and the needle, means for driving the sewing shaft, a rotary work supporting horn and a presser foot, a resilient member for forcing the presser foot against the work, means actuated from sewing shaftfor intermittently lifting the press 1' foot to permit the work to be fed, a power operated presser foot lifting mechanism normally inoperative during operation of the machine and thrown into operation after the sewing shaft is disconnected from the driving means to lift the presser foot from the work, mechanism under the control of the oper ator for disconnecting the sewing shaft from the driving means and for stopping the machine with work supporting horn and a prcsser foot, a resilient member for forcing the presser foot against the work, means actuated from the sewing shaft for intermittently lifting the presser foot to permit the work to be fed, mechanism under the control of the operator for disconnecting the sewing shaft from the driving means and rendering the needle actuating connections for inoperative upon disengagement of the needle from foot to permit the work to be fed, a needle thread i 4. A sewing machine'having, in combination, stitch-forming devices including a straight hook needle, a sewing shaft, a'lever actuated from the sewing, shalt normally connected to the sewing shaft to actuate the needle, a rotary work supporting horn and apresser foot, mechanism under the control of the operatorfor disconnecting the sewing shaft from the needle actuating lever at th end of a seam with the needle dis engaged from the work, and locking devices operated by the needle actuating lever to prevent movement of the presser foot while the needle engages the work and to release the presser foot when the needle is disengaged from the work.

5. A sewing machine having, in combination, stitch-forming devices including a straight hook needle, a sewing shaft, a rotary work supporting horn and a presser foot, means actuated from the sewing shaft for intermittently lifting the presser foot to permit the work to be fed, a needle thread lock, a power operated mechanism normally inoperative during operation of the machine and thrown into operation at the end of a seam, connections to the power operated mechanism for lifting the presser foot and other connections to the power operated mechanism for opening the thread lock, said connections being independently operable to prevent opening of the thread look by movement of the presser foot during operation of the machine.

6. A sewing machine having, in combination, stitch-forming devices including a straight hook needle, a sewing shaft for actuating the stitchforming devices, a rotary work supporting horn and a presser foot, a needle thread lock, means for driving the sewing shaft, a foot treadle for connecting and disconnecting the driving means from the sewing shaft, a manually operated member for raising the presser foot from the work, a power operated mechanism normally inoperative during operation of the machine but set in motion as the foot treadle acts to disconnect thedriving means from the sewing shaft, connections to the power operated mechanism for lifting the presser foot, and other connections to the power operated mechanism for opening the thread look at the end of a seam, said connections being independently operable to prevent the thread look from being opened when the presser foot is lifted by the manually operated member.

7. A sewing machine having, combination, stitcli forming devices including a straight hook needle, a sewingshaft, a lever actuated from the sewing shaft and connected to actuate the needle, a rotary work supporting horn and a presser foot, mechanism under the control of the operator for disconnecting the sewing shaft from the needle actuating lever at the end of a seam with the needle disengaged from the work, looking devices operated by the needle actuating lever to prevent displacement of the presser foot from the work while the needle engages the work and to release the presser foot while the needle is disengaged from the work, a manually operated member for lifting the presser foot from the work, and connections between the manually operated member and the locking devices for releasing the presser foot with the needle in any position.

8. A sewing machine having, in combination, stitch-forming devices including a straight hook needle, a sewing shaft, a rotary work supporting horn and a presser foot, means actuated from the sewing shaft for intermittently lifting the presser look, a shaftconnected to the presser foot to be rocked .as the presser foot is lifted, a lever fu1-.

crumed loosely on the shaft and connected to the needle thread lock, a power operated mechanism normally inoperative during operation of the machine but thrown into operation at the end of the seam to open the needle thread lockby operation of the lever, and arm having a projection fixed to the shaft, said projection extending into the path of the lever for rocking the shaft upon movement of the lever but permitting the shaft to he turned without moving the lever as the presser foot is lifted during operation of the machine.

A sewing machine having, in combination, sti "h-iorming devices including a straight hook needle, a sewing shaft, means for driving the sewing shaft, a rotary work supporting horn and a presser foot, means actuatedfrom thesewing shaft for intermittently lifting the presser foot to permit the work to be fed, a needle thread look, a power operated mechanism normally inoperative during operation of the machine and thrown into operation after the machine is disconnected from the driving means, locking devices for preventing movement of the presser foot while the needle engages the work, mechanism under the control of the operator for disconnecting the sewing shaft from the driving means and for rendering the locking devices inoperative, connections to the power operated mechanism for lifting the presser foot, and other connections to the power operated mechanism for opening the thread lock, said connections be ing independently operable to prevent opening of the thread look by movement of the presser foot during operation of the machine.

10. A sewing machine having, in combination, stitch-forming devices including astraight hook needle, a sewing shaft for actuating the stitchforming devices, a rotary work supporting horn and a presser foot, a needle thread lock, means for driving the sewing shaft, a foot treadle for connecting and disconnecting the driving means from the-sewing shaft, locking devices operated from the sewing shaft to prevent movement of the presser foot while the needle engages the work, a manually operated member for releasing the presser foot from the locking devices and for lifting the presser foot from the work, a power operated mechanism normally inoperative during operation of the machine but set in motion as the foot treadle is moved to disconnect the driving means from the sewing shaft, connections to the power operated mechanism for unlocking and lifting the presser foot, other connections to the power operated mechanism for releasing the thread from the thread lock, said connections being independently operable to prevent the thread from being released when the presser foot is unlocked and lifted by the manually operable member.

11, A sewing machine having, in combination, stitch-forming devices including a straight hook needle, a sewing shaft, a rotary work supporting horn and a presser foot, a needle thread look, a shaft connected to lift thepresser foot when rocked in one direction, a lever fulcrumed loosely on the shaft, a link connected at one end to the needle thread lock, the other end being operated in one direction by movement of the lever, a power operated pawl member arranged to be moved from an inoperative position into engagement with the lever at the end of the seam to actuate the lever and open the needle thread' lock as the machine is brought to rest, an arm fixed to the shaft and provided with a projection for engagement with the lever to cause the lever to rock the shaft and lift the presser foot when the lever moves the link to open the needle thread lock, and a spring connected between the arm and the lever acting to maintain the lever

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