US3460497A - Stitching control mechanism for chainstitch sewing machines - Google Patents

Description

3,460,497 STITCHINC CONTROL MECHANISM FOR CHAINSTITCH SEWING MACHINES Filed Sept. 20. 1967 H. ORTH ET AL Aug. 12, 1.969

2 Sheets-Sheet 1.

INVENTORS HANS oer/g wow/G flea/v4 Aug. 12,1969

Filed Sept. 20, 1967 H. ORTH ET AL STITCHING CONTROL MECHANISM FOR CHAINSTITCH SEWING MACHINES INVENTORS HMIS oer/4 Lt/DN/fi M BY (MBA Y alwvlae TML 2.47/1

4 rme/nsy United States Patent 3,460,497 STITCHING CONTROL MECHANISM FOR CHAINSTITCH SEWING MACHINES Hans Orth, Alsenborn, Rhineland, Pfalz, Ludwig Franz,

Kaiserslautern, Rhineland, Pfalz, and Urban Divivier, Obermohr, Rhineland, Pfalz, Germany, assignors to G. M. Pfaff AG, Kaiserslautern, Pfalz, Germany, a corporation of Germany Filed Sept. 20, 1967, Ser. No. 669,014 Claims priority, application Germany, Oct. 10, 1966, P 40,533 Int. Cl. D05b 1/06, 1/10, 27/00 US. Cl. 112-200 11 Claims ABSTRACT OF THE DISCLOSURE In a chainstitch sewing machine of the type having an oscillating looper, a seam being sewn is temporarily interrupted without stoppage of the machine by disabling the stitch formation in causing the looper to change from its normal elliptical operating path encircling the needle to a linear oscillating path in front of the needle, as viewed in the work feeding direction. For this purpose, the eccentric rod of the eccentric oscillating drive for effecting the needle-avoid movements of the looper in the Work feeding direction includes a yielding coupling adjoining the input end of said drive, with special control means, operable by means of a foot pedal, beng provided to rarrest said drive at a point intermediate the looper and said coupling and at a time position of the stitching cycle corresponding to the instant of the point of the looper seizing or entering the needle-thread loop.

The present invention relates to chainstitch sewing machines of the type including a reciprocatory needle and an oscillating hook or looper operated along a substantially elliptical path encircling the needle for the formation of chainstitches in a fabric or workpiece being operated on.

It is already known, in the use of prior stitching control devices based on the interruption of a seam being sewn, to temporarily retract the looper from its normal operating position to an inoperative position in which the point of the looper is unable to seize the needle-thread loop during a stitching cycle, to thereby prevent the stitch formation in cooperation with the needle. Arrangements of this type have the disadvantage of failing, during the feed movements of the fabric or workpiece by the feed dog of the machine, to draw off the needle thread from its supply bobbin, involving thereby an undesired tensioning of the thread and swelling of the fabric behind the needle or stitching point and affecting the appearance of the seam being sewn.

Accordingly, an important object of the present invention is the provision of improved stitching control means for a chainstitch sewing machine of the referred to type, operative by temporarily disabling the stitch formation and being devoid of the foregoing and related difficulties inherent in the prior control devices of this type.

A more specific object of the invention is the provision of stitching control means for a chainstitch sewing machine of the referred to type, operative, by means of a foot pedal or the like control member, in disabling the stitch formation by the looper and needle, without interruption of the normal needle-thread seizing and shedding movements of the looper.

Another object of the invention is the provision, in conjunction with stitching control mechanism of the above referred to type, of stitching length control means operably associated with the foot pedal or the like control member of said mechanism, to temporarily reduce the ice stitching length during the initial operation of said memher, for the automatic sewing of a number of tacking stitches at the end of a seam to be interrupted.

The invention, both as to the foregoing and ancillary objects as well as novel aspects thereof, will be better understood from the following detailed description of a preferred practical embodiment, taken in conjunction with the accompanying drawings forming part of this specification and in which:

FIG. 1 is an elevational side view, shown partly in section, of control mechanism mounted underneath the cloth plate of an otherwise conventional chainstitch sewing machine embodying the improvements according to the invention;

FIG. 2 is a fragmentary enlarged end view of the mechanism according to FIG. 1;

FIG. 2a is a diagrammatic view illustrating the looper path during stitch formation and interruption, respectively; and

FIG. 3 is a perspective exploded view showing conventional stitch-controller mechanism suitable for the sewing of tacking stitches in a machine according to the invention.

Like reference numerals denote like parts and elements in the different views of the drawings.

With the foregoing objects in view, the invention involves generally the provision of control means to temporarily arrest, at a position of the looper seizing the needle-thread loop during a stitching cycle, the oscillating drive of a chainstitch sewing machine effecting the needleavoid movements of the looper or, in other words, to change from the normally elliptical looper oscillating path or orbit encircling the needle to a substantially linear oscillating path on one side of said needle.

While the stitch formation by the looper and needle may be disabled in this manner for the temporary interruption of a seam being sewn without stoppage of the machine, the needle-thread is seized by the looper during each downward stroke of the needle or passage through the fabric, whereby to draw off the needle thread during the forward feed movement of the fabric by the feed dog, in substantially the same manner as during normal stitchforming operation of the machine.

An especially simple solution of the foregoing problem may be achieved by the provision of a resilient force-locking coupling member interposed in the path of the oscillating drive effecting the transverse excursions or needleavoid movements of the looper. More particularly, where this drive is derived from an eccentric and eccentric rod, forming a rotary-to-oscillating motion converter driven from the drive shaft of the sewing machine, the eccentric rod is advantageously comprised of two parts or sections relatively slidably mounted between two limit positions by determined suitable stop means, said parts being normally urged to a first limit position by the action of a compression spring or the like. The section of the eccentric rod connected to the looper carries a locking element adapted to engage a further locking element actuated by the control means (foot pedal), to arrest the eccentric rod in the other of said limit positions and to thereby disable the stitch formation, in the manner as will become further apparent as the description proceeds.

in order to avoid damage to the eccentric rod during engagement by the locking element, the latter is advantageously connected to the control member via elastic coupling means.

Chainstitches have the well-known characteristic that they are easily drawn off or loosened at the end of a seam. In order to avoid this defect, it is necessary to sew a few tacking stitches before reaching the end of a seam or interrupting point. According to an improved feature of the invention, the control member for the arresting of the needle-avoid looper oscillations is operably connected, via a cam or the like mechanism, with the setting lever of a conventional stitch-controller, to temporarily reduce the stitching length during the initial movement of said member (foot pedal, etc.), to sew a number of tacking stitches, in a manner as will become further apparent from the description in reference to the drawings.

Referring more particularly to FIGS. 1 and 2, the numeral 1 indicates the cloth plate forming part of the frame of a conventional chainstitch sewing machine and below which is journalled a first or lower drive shaft 2 driven in a known manner, via a chain belt 3 or the like transmission means, by the main drive or arm shaft of the sewing machine (not shown). Mounted upon the shaft 2 is a gear 4- meshing with a further gear 6 which is secured upon a second or "upper drive shaft arranged parallel to the shaft 2 and also journalled in the frame of the machine.

Mounted upon the upper drive shaft 5 is an eccentric 7 which is embraced by the ring-shaped end of the upper section 8 of a two-part eccentric rod 9. Section 8 is jointed to the remaining lower section 11 of the eccentric rod 9 through a pivot pin 10, while the lower end of the section 11 is shaped in the form of a ball socket in which is mounted the spherical-shaped end of a lever arm 13 having its opposite end rigidly connected to the hook or looper carrier 12 of the sewing machine which in turn supports, in a preferably exchangeable manner, the chainstitch looper 14. The latter may carry a looper thread for cooperation with the reciprocatory needle 15 and needle thread, for the production of double chainstitches in the workpiece being operated on. However, a non-thread-carrying looper may be provided for the production of simple chainstitches, as is understood.

The looper carrier 12 is rotatively Supported at its lower fork-shaped end 17 by a bolt 16 forming part of a looper support 18 from which extends a lever arm 19, FIG. 2. The latter is in turn jointed to the lower end of an eccentric rod 20 embracing at its upper end an eccentric 21 mounted upon the lower drive shaft 2. The hook support 18 is in turn rotatively mounted about a bolt 22 which is secured to a depending supporting wall 23 fast on the plate 1.

The eccentric rod 20 is composed of two halves or sections 24 and 25 interengaging one another telescopefashion. The lower section 24 of the eccentric rod is fitted with a cross-pin 26 projecting through a longitudinal slot 27 in the upper section 25. A series of dishshaped or cup springs 28 engaging, on the one hand and via a washer 29, the pin 26, and engaging, on the other hand and via a further washer 30, a locking ring 32 secured to the lower section 24, serve to maintain the sections 24 and 25 of the eccentric rod 20 in continuous force locking engagement with one another. More particularly, with the cross-pin 26 engaging the upper end of the slot 27, as shown in FIG. 1, the eccentric rod assumes its shortest length during normal or stitch-forming operation of the sewing machine.

The springs 28 are so designed and biased or tensioned as not to become appreciably compressed by the forces acting upon the eccentric rod 20, that is, to provide the equivalent of a conventional rigid eccentric rod during the normal or stitch-forming operation of the machine.

The section 24 of the eccentric rod 20 is fitted with a depending angular or hook-shaped lower end 33 forming a locking element adapted to engage or lock with the hook-shaped end 34 of a further locking element 35 which is secured to the end of a control shaft 36 journalled in both the wall 23 and a further wall 37 depending from the plate 1. Secured to the shaft 36 is a pin 38 which extends through a slot 39 in the locking element 35, whereby to allow the latter to rotate relative to the shaft 36 through a limited angular range determined by said slot.

A torsion spring 49, having one end affixed to the element 35 and having its opposite end afiixed to a setting ring 41 threadedly mounted upon the shaft 36 serves to urge the locking element 35 to a limit position of the pin 38, as shown in the drawing, FIG. 1.

A further torsion spring 42, having one end affixed to the wall 23 and having its other end affixed to a further setting ring 43 mounted upon the shaft 36, serves to rotate shaft 36 to a position of engagement of a lever 44, secured to the opposite end of said shaft, with an abutment pin or stop 45 mounted in and projecting from the wall 37. Lever 44 is fitted with a pivot pin 46 to which is connected the operating link 47 of a foot pedal or the like operating member (not shown) provided for actuation or manual control by the operator, in a manner as will becme more apparent as the description proceeds.

Further connected to the end of the shaft 36 is a control lever 48 to the free end of which is affixed, by means of a safety ring 49, a displaceable pin 50. The latter carries, at its free end, a roller or cam follower 51 being urged against the path of a flat cam 53 rotatively mounted, about a control or setting shaft 54, below the base plate 1 and serving for the control of the stitching length, in the manner described in greater detail hereafter. Cam 56 has an edge forming a cam surface or curve engaged by the roller 51 of the control lever 48 during the downward deflection of the latter from the position shown in full lines towards the dashed-line position, FIG. 2. The lower part of the cam 53 is formed, on its upper flat face, with a chamfered surface 56, to enable the roller 51 to return to the initial or full-line position of the lever 48 without engaging the edge 55, for the purpose which will become further apparent from the description of the operation of the device.

The setting shaft 54, being journalled in a position parallel to the shafts 2 and 5 in the frame of the machine, serves for the adjustment of the feed stroke of the feed dog 57, FIG. 3, disposed adjacent to the stitching point of the sewing machine and being supported in a conventional manner by a feed dog bar or carrier 58. The latter embraces with its fork-shaped forward end 59 an eccentric 60 mounted upon a further rotating shaft driven by the main drive shaft 2 through suitable transmission means (not shown) and serving to impart conventional rise and fall movements or components to the feed dog 57.

Jointed to the opposite end of the feed dog bar 53 is a rocking member or link 62 supported by a rockshaft 63 which is journalled in the wall 23 in a position parallel to the drive shaft 2. Rockshaft 63 is operably connected, via a crank 64 and crank pin 65, with a link 66 which is in turn operably connected, via a bolt 67, with a further link 68. The latter is connected, via a pin 69, with a crank 70 secured to the control shaft 54.

Component oscillating movement of the feed dog 57 in the feed direction is effected, via an eccentric rod 72 and the bolt 67, by a further eccentric 71 mounted upon the main drive shaft 2, whereby to result in the normal periodic rectangular-shaped feed movement of said dog by cooperation of the eccentric 60 with the eccentric 71, in a manner well known and understood by those skilled in the art.

Setting shaft 54 is connected, via a ball-joint link 74, FIG. 3, with an arm of a double-arm lever 75 having an axis 76 journalled in the frame of the machine and arranged with its remaining arm engaging a curved slot or groove 77 of a control disk or stitch controller 78 also journalled in said frame. A torsion spring 79 encircling the shaft 54 and afiixed at one end to the wall 37 and afiixed at its other end to said shaft, acts to urge the latter to an angular position, whereby to cause the end of the lever 75, projecting into the groove 77 of the disk 78, to resiliently engage a wall 80 of said groove, to thereby enable adjustment of the feed stroke of the sewing machine by manually setting the disk 78, in a manner well known. More particularly, for the latter purpose, rotation of the shaft 54 results in a rotation of the crank 70, the latter in turn causing a displacement of the axis of the pin 69, or rotating axis of the link 68, relative to the axis of the pin 65. As a consequence, the oscillations of the bolt 67 by the eccentric rod 72 cause the link 68 to describe a purely rotary motion, while the link 66 is subjected, aside from this rotating motion, to a further motion relative to the rockshaft 63, which relative motion is transmitted, via the crank 64, as an oscillating motion to the rocker arm 62 and, in turn, to the feed dog bar 58, thus providing the necessary oscillating component of the feed dog 57 in the feed direction. The amplitude and sense of the oscillations are determined, in a known manner, by the relative displacement of the axes of pins 65 and 69, determined by the setting of the stitch controller 78, in either direction from the aligned position of the pins corresponding to zero feed of the dog 57.

In operation, the looper 14, FIGS. 1 and 2, is subjected to a composite motion described by its point 14a and indicated at p in FIG. 2a, said motion being comprised of a first oscillating component in the x-direction about the bolt 17 and a second oscillating component in the y-direction about the bolt 22, respectively. More particularly, in the example shown by drawing, the looper 14 receives its movement (x-direction) for the seizing and shedding of the needle thread loop from the shaft 2 via gears 4 and 6, eccentric 7 and eccentric rod 9 operating the looper carrier 12, while the needle-avoid movement (y-direction) of the looper is applied to said carrier via the drive shaft 2, eccentric 21, eccentric rod 20 and the looper support 18 oscillating about bolt 22. As a consequence, the combined result of both oscillating components is the well-known elliptical operating path or orbit p of the hook or looper 14 about the needle 15, FIG. 2a, necessary for the formation of chainstitches in the workpiece being operated on.

In order to interrupt, according to the improvement of the present invention, a seam being sewn by temporarily disabling the stitch formation by the looper 14 and needle 15, the operator depresses the foot pedal, whereby to effect, by way of the linkage 47 and against the action of the spring 42, rotation of the lever 44 which, in turn, causes a deflection of the locking element 35, via shaft 36, to cause its hook-shaped end 34 to engage behind the hook 33 of the lower eccentric rod section 24. In practice, the end 34 of the element is able to engage the hook 33 in the lowermost position only of the eccentric rod 20, while frictionally sliding upon the edge of said hook in all the intermediate positions. As a consequence, the initial control impulse by the shaft 36 is stored by rotation of the spring 40 until the hook 33 reaches its lower limit position, to enable engagement and locking of the parts in the manner described.

Simultaneously with the initial rotation of the shaft 36 by the foot pedal or the like control member, the control lever 48 is deflected, resulting in a corresponding rotation of the cam 53 by the follower 51 in accordance with the shape of the control curve 55. The resultant rotation of the setting shaft 54, FIG. 3, in turn causes the free end of the lever 75 to be disengaged, against the action of spring 79, from the wall 80 of the control groove 77, while simultaneously displacing the pin 69 relatively to the pin 65 to an extent to substantially temporarily reduce the feed stroke of the dog 57, in such a manner as to cause the machine to sew a few closely adjoining tacking stitches for the locking of the end or interrupting point of the seam being sewn.

During continued depression of the foot pedal and rotation of the control lever 48 beyond the position shown in dotted lines in FIG. 2, the stitching length is again increased to its normal adjusted value as a result of the return of the cam 53 by the spring 79, whereby to cause the end of the lever 75 to again engage the wall 80 of the groove 77, to thereby restore the original stitching length set by the disk or controller 78. Due to the interruption or disabling of the needle avoid movement of the looper 14 as described in the following, no stitches are produced or the seam interrupted as long as the foot pedal is held in the depressed or operative position by the operator.

The interruption of the stitch formation will be fur ther explained in the following. After the hook-shaped end 34 of the locking element 35 has arrested the section 24 of the eccentric rod 20 in its lowermost oscillating position in the manner described in the foregoing, the oscillating movement imparted by the eccentric 21 to the upper section 25 of the eccentric rod 20 is taken up by the spring 28, whereby the looper support 18 is arrested or locked in the limit position of the looper of its needleavoid movement -(y-direction) or position assumed at the instant of the point 14a of the looper seizing the needle thread loop during a stitching cycle or operation of the sewing machine. This locking position of the looper is indicated in dashed lines at 14 in FIG. 2a. As a result of the suppression of the needle, avoid movement of the looper 14, the latter now oscillates along a linear path p in front of the needle, as viewed in the feeding direction f, FIG. 2a.

While the stitch formation is suppressed in this manner, that is, with the looper 14 oscillating in a linear path on one side of the needle 15 instead of in the normal elliptical path encircling the needle, the looper performs its normal loop seizing and shedding operations, whereby to avoid the previous and related difficulties and defects as pointed out in the foregoing.

More particularly, as the operation of the sewing machine is continued, with the looper oscillating along the linear path p, the needle thread loop is seized by the hook or looper 14 in the norm-a1 manner during each operating cycle of the machine, whereby to effect both a withdrawal of both the needle and looper threads, in the case of a double chainstitch machine, and casting oil or shedding of said loop without, however, the latter being interlinked with the needle or needle thread, respectively, as during the normal or stitch-forming operation of the machine.

The stitch formation is thus interrupted until the foot pedal or equivalent control member is released by the operator, whereby to allow the shaft 36 to return, through the action of the spring 42, to its normal or rest position in which the lever 44 engages the pin 45. At the same time, the hooked end 34 of the locking element 35 is disengaged from the hook 33 or": the eccentric rod section 24, thereby enabling the eccentric rod 20 to assume its normal function and to restore the normal stitch'forming operation of the machine.

At the same time, the control lever 48 together with the roller or cam follower 51 is returned to the starting (solid line) position, during which movement the chamfered surface 56 of the cam 53 is engaged by said roller, urged against surface 56. As a consequence, the roller 51 by-passes the cam 53 without displacing the latter, to thereby prevent the sewing of tacking stitches upon the resumption of the stitch formation or starting of a new seam.

The fact that the control lever 48 is enabled to return to its rest position without displacing the cam 53 makes it possible for the spring 42 to provide only the force necesary for the return of the shaft 36, that is, without requiring the additional effort for deflecting the cam 53 against the action of the spring 79. For the latter reason, a relatively soft spring 42 is sufficient, whereby the force exerted by the operator is reduced to a minimum.

In the foregoing the invention has been described in reference to a specific exemplary device and practical embodiment. It will be evident, however, that variations and modifications, as well as the substitution of equivalent parts or elements for those shown for illustration,

may be made without departing from the broader spirit and purview of the invention. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense.

We claim:

1. In a chainstitch sewing machine including a reciprocatory needle, an oscillating looper, and means to operate said looper along a substantially elliptical path encircling said needle, said means comprising a drive shaft, first motion-transmitting means including rotary-to-oscillating motion conversion means and operably connecting said shaft with said looper, to oscillate the same in a first component direction of said path for the production of the needle-thread loop seizing and shedding movements during a stitch-forming cycle of the machine, and second motion-transmitting means including rotary-to-oscillating motion conversion means and operably connecting said shaft with said looper, to oscillate the same in a coordinate component direction to said first direction for the production of the needle-avoid oscillating movements; the improvement consisting in the provision of (l) resilient coupling means interposed in the path of and forming an effective coupling element of said second motion-transmitting means,

(2) said resilient means being adapted to offer a resistance sufiicient to afford oscillating force transmission from said shaft to said looper during normal stitchforming operation of said machine, and

(3) control means having a normally disengaged rest position and an engaged operative position, to temporarily lock said second motion-transmitting means in said operative position at a point intermediate said looper and said resilient means and at a timed position of its operating cycle corresponding to the instant of said looper seizing the needle-thread loop during a stitch-forming cycle of said machine,

(4) whereby said looper performs a substantially linear oscillating movement on one side of said needle in the operative position of said control means thereby interrupting formation of said stitch but continuing to seize and subsequently shed the needle thread during each cycle of operation of the machine.

2. In a chainstitch sewing machine as claimed in claim 1, said elliptical path being arranged with its longer dimension which coincides with the needle-avoid looper movement and being at a right angle to its shorter dimension which coincides with the needle-avoid looper movement, said shorter dimension being in line with the feed direction of the workpiece being operated on by said needle and looper.

3. In a chainstitch sewing machine as claimed in claim 1, said second rotary-to-oscillating motion conversion means being comprised of an eccentric driven by said shaft and an eccentric rod operably connected therewith and composed of two relatively slidable member and stop means defining two limit positions therebetween, said resilient means consisting of a compression spring interposed between said members, to resiliently urge the same to one of said limit positions, a locking element connected to said control means, and a hook-shaped extension of the member of said eccentric rod located on the side away from said eccentric and adapted to lock with said element in the operative position of said control means.

4. In a chainstitch sewing machine as claimed in claim 3, said hook-shaped extension being adapted to slidably engage said locking element during initial operating movement of said control means and to firmly interlock with said element upon said eccentric rod reaching a position corresponding to the instant of the looper seizing the needle-thread loop during a stitch-forming cycle of said machine.

5. In a chainstitch sewing machine as claimed in claim 3, said relatively slidable members including means for telescopically mounting one member within the other 6. In a chainstitch sewing machine as claimed in claim 3, said control means beang comprised of a feed pedal, a lever journalled at one end carrying said locking element and having its opposite end operably connected with said pedal.

7. In a chainstitch sewing machine as claimed in claim 1, said first and second rotary-oscillating motion conversion means being comprised of a first and second eccentric driven by said shaft and first and second eccentric rods therefor, respectively, and a looper carrier supported for oscillation in two coordinate directions and operably connected with the output ends of both said transmission means, said second eccentric rod being comprised of a first member adjoining said second eccentric and a second member adjoining said second motion-transmitting means and relatively slidably mounted upon said first member within two limit positions therebetween, said resilient means consisting of a compression spring resiliently urging said members to one of said limit positions, a locking element carried by said control means, and a hookshaped extension of said second member of said eccentric adapted to lock with said element in the operative position of said control means.

8. In a chainstitch sewing machine as claimed in claim 7, said spring in the compressed condition offering a resistance to enable of normal oscillating force transmission by said second eccentric rod during the stitch-forming operation of said machine and to take up the oscillations imparted by said second eccentric to said first eccentric rod member during locking of said second eccentric rod member by said control means.

9. In a chainstitch sewing machine as claimed in claim 1, including a feed dog and a stitch-controller operably connected therewith, to adjust the stitching length by varying the feed stroke of said dog, and further control means operably connecting said first control means with said stitch-controller, to temporarily reduce the stitching length during an initial fractional movement of said control means for the sewing of a number of tacking stitches prior to the interruption of the seam being sewn.

10. In a chainstitch sewing machine as claimed in claim 9, said further control means including a cam and cam follower mechanism adapted to temporarily reduce the stitching length during said fractional initial advance movement of said first control means, and means to disable said mechanism during the return of said control means to its rest position.

11. In a chainstitch sewing machine including a reciprocatory needle, an oscillating looper, and first and second drive means to, respectively, apply to said looper a first oscillating component movement, to produce needle-thread loop seizing and shedding looper movements, and a second oscillating component movement coordinated and synchronized with said first oscillating movement, to produce needle-avoid looper movements, whereby said looper moves along an elliptical operating path encircling said needle during the stitch-forming operation of said machine, to produce chainstitches in cooperation with said needle in a workpiece operated on, the provision of means to temporarily disable the stitch formation for the interruption of a seam being sewn without stoppage of said machine, comprising in combination:

(1) yielding coupling means interposed in the path and at a point adjoining the input of said second drive means,

(2) said yielding coupling means being adapted to offer a resistance sufficient to afford effective oscillating force transmission by said second drive means during normal stitch-forming operation of said machine, and

(3) control means having a normally disengaged rest and an engaged operative position, to temporarily arrest said second drive means at a point intermedi- 3,460,497 9 10 ate said looper and said yielding coupling means References Cited and at a timed position of said looper seizing the UNITED STATES PATENTS needle-thread loop during a stitching cycle of said machine 85,364 7/1921 De Voe 112.. 2 (4) whereby said looper performs a substantially linear 5 g i i oscillating movement on one side of said needle ee er et a in the operative position of said control means there- H HAMPTON HUNTER Primary Examiner by interrupting formation of said stitch but continuing to seize and subsequently shed the needle US. Cl, X R thread during each cycle of operation of the machine. 10 112-210

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