US2955553A

US2955553A - Rotary feeder

Info

Publication number: US2955553A
Application number: US597228A
Authority: US
Inventors: Ragnar W Winberg
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-07-11
Filing date: 1956-07-11
Publication date: 1960-10-11
Anticipated expiration: 1977-10-11

Description

Oct. 11, 1960 R. w. WINBERG 2,955,553

ROTARY FEEDER Filed July 11, 1956 2 Sheets-Sheet 1 FIG. I. M

IN VEN TOR. R46 NAQ W/NS E 26 A770 ENS) Oct. 11, 1960 w. wlNBERG 2,955,553

ROTARY FEEDER Filed July 11, 1956 2 Sheets-Sheet 2 1 ZIIIIIIIIIIIIIIIIIIIIJ F 6 INVENTOR. 1246mm M W/IVBEkG:

F I G. 5. BY ,1 in 4 States Patent ROTARY FEEDER Ragnar W. Winberg, 115 W. Elder Ave.,

' Floral Park, N. Y. 7

Filed July 11, 1956, Ser. No. 597,228

" 12 Claims. (Cl. 112--211 The present invention relates to improved workfeeding mechanisms for sewing machines, and in particular to a powered rotary feeder for a sewing machine which is particularly suited for feeding thin and bodyless materials. i The well known drop feed sewing machine, most prevalen tly employed for industrial use, includes a springbiased presser foot which cooperates with an oscillating feed dog for advance of assemblies to be stitched along a feed or stitch path in relation to the reciprocating needle of the machine. With the present day advent of synthetic fabrics and synthetic threads, such sewing machines have been found to exhibit pronounced dis-advantages, particularly from the standpoint of obtaining substantially fiat, pucker-free seams.

Illustrative of the many problems which are encountered is an attempt to provide flat seams in materials of nylon or nylon blends using a nylon needle thread and bobbin thread. Stitching with a machine having a conventional presser foot and feed dog results in pronounced puckering or gathering along the seams. It is thought that the puckering is brought about by the top or needle thread which is of man-made fibers and rather easily stretched. The normal tension placed on the thread in advance of the needle for proper operation of the sewing machine is believed to cause gathering along the stitched seam when the top thread relaxes after the formation of the stitch. This effect, coupled with the intermittent nature of the feed and the resultant pulling forces on the material results in puckered seams, leaving much to be desired from the standpoint of manufacturing quality.

In an attempt to correct the gathering problem, machine operators are instructed to pull the work both fore and aft of the needle to place tension along the stitch line so that when the needle thread relaxes, the body of the material may be relaxed more or less in the same proportion with a view to obtaining a flatter seam. Apart from the fact that such manual manipulation re-' quires the operator to exhibit extreme dexterity, it has been found that as a practical matter the average ma chine operator does not have the skill and judgement to correct for this difficulty. Further, since the types of stitching operations and the materials employed are frequently changed, it becomes economically unfeasible and impractical to leave the solution of this problem to the discretion of the individual operator.

Broadly, it is an object of the present invention to provide an improved feeding mechanism for a sewing machine. the present invention to provide a rotary feed attachment for a sewing machine which makes possible stitching of thin and bodyless materials, particularly synthetic or mand-made fibers, in a manner substantiallyfree o pucker or gathering along stitched seams.

In my United States Patent No. 2,741,197 of April 10, 1956, there is disclosed a rotary attachment including a pair of driven feeding and pulling wheels at opposite Specifically, it is within the contemplation of 2,955,553 Patented Oct. 11, 19.60

sides of a needle which are arranged in relation to each other to provide intermittent feeding action at locations on both sides of the needle and pulling action rearwardly offthe needle and substantially along the stitch line. Said attachment feeds conjointly with the feed dog-of themachine, and is particularly suitable for positive compound feed of multiple-layer assemblies. Although marked improvement in the problem of gathering is realized with said attachment, particularly when compared to the conventional drop-feed sewing machine, there still exists a need for a device which is tailored to meet the problems of handling synthetic materials which are t be stitched together by synthetic threads.

' I have found'that specially constructed driven feed wheels disposed at opposite sides of a needle and continuously driven in contact with the feed plate or bed of the sewing machine brings about a marked and heretofore unattainable improvement in the character of the stitched seam. The feed Wheels are fabricated with yieldable Work-engaging surfaces so that successive peripheral portions of the work engaging surfaces are flattened against the feed bed or plate during rotation of the feed wheels whereby the materialis tensioned in the stitching zone. This tensioning, which is transverse or laterally of the stitch line controls the manner in which the thread is placed into the material or fabric so that and throat plate of the conventional sewing machine are removed and replaced with a darning plate. The presser foot of the machine is. removed and replaced by a pair of continuously driven feed wheels which are disposed at opposite sides of the needle and are inclined relative to each other whereby the work-engaging sur-' facm of the wheels are positioned to contact the plate at opposite sides and rearwardly of the needle. The work-engaging surfaces are yieldable and are urged against the plate to provide area contacts with the material, which area contacts are continuously eifective to pull the material past the needle, with the material drawn taut during and following the stitching operation.

As a further feature of the invention, the feed wheels. may be toed outwardly rearwardly of the needle to increase the lateral tensioning of the material. Alternatively, the feed wheels may be toed inwardly rearwardly of the needle to somewhat diminish the lateral tensioning. Thus the degree of tautness under which the material passes through the stitching zone may be readily controlled.

As a still further feature of the invention, a specially constructed plate or feed bed may be employed in conjunction with the driven feed wheels for effectively increasing the area of contact and the zone of tensioning.

Advantageously, the powered top feed of the present invention may be attached to any conventional sewing machine by replacing standard machine parts. The presence of the driven rotary attachment does not encroach upon the Work handling space immediately adjacent the needle, permits ready visibility of the work, and does not interfere with maneuverability.

The above brief description, as well as further objects, features and advantages of the present invention will be best understood by reference to the following detailed description of a presently preferred, but illustrative emtaken from the left of Fig. l and showing the details of the outermost feed wheel and its cooperation with the underlying darning plate;

Fig. 3 is a sectional view taken substantially along the line 33 of Fig. 2 and looking in the direction of the arrows;

Fig. 4 is a plan view of the attachment, with parts broken away and sectioned in the interests of simplicity and clarity;

Fig. 5 is an elevational view, with parts in section, taken substantially along the longitudinal center plane of the attachment in Fig. 3 and looking toward the right;

Fig. 6 is a plan view of the darning plate, with the feed wheels shown in phantom, to illustrate the location of the effective work-engaging surfaces when the feed wheels are symmetrically in relation to each other fore and aft of the needle;

Fig. 7 is a view similar to Fig. 6, but showing the effective work-engaging surfaces when the feed wheels are toed outwardly rearwardly of the needle; and

Fig. 8 is a view similar to Fig. 6 but showing the effective work engaging surfaces when the feed wheels are toed inwardly rearwardly of the needle.

Referring now specifically to the drawings, the numeral 10 generally designates a conventional drop feed sewing machine which includes a body 12 from one end of which arises a hollow standard supporting a horizontallyextending arm 14 which terminates in an upright head 16 which overhangs the feed bed or base 18 of the machine. Extending longitudinally within the horizontal arm 14 is a drive shaft (not shown) which is coupled to a drive motor by a belt and pulley coupling 20 outwardly of the hand wheel 22 of the machine. Within the head or end section 16 of the machine is a vertically reciprocable presser foot bar 24 which is spring biased downwardly by a spring 26 having provision for adjustment of spring tension. Normally the presser foot bar 24 supports a conventional presser foot which is attached at the lower end 24a of the presser foot 24. Arranged forwardly of and parallel to the presser foot bar is a needle bar 28 which supports the needle 30. The needle is driven through a vertical stitch-forming stroke during each rotary traverse of the main shaft of the sewing machine. Appropriate coordinated mechanisms are arranged to drive the needle bar 28 and bobbin mechanisms to achieve stitching, as is well understood in the art. In that the details of the sewing machine are conventional per se, further description is dispensed with.

In accordance with the present invention the conventional throat plate of the sewing machine is replaced by a darning plate 32 formed with a needle hole 34; and the conventional presser foot is replaced by a rotary feeder, generally designated by the reference numeral 36, which is attached to the bottom or lower end 24a of the presser foot bar 24. The rotary feeder 36 embodies a pair of driven

feed wheels

38, 40 which cooperate with the darning plate or feed bed 32 to feed material past the needle 30 for stitching. The

feed wheels

38, 40 are of like structure and include conical work-

engaging surfaces

38a, 40a which are so constructed and arranged as to be yieldably engaged against the darning plate 32 to present successive flattened work-contacting surfaces or areas in response to rotation of the

feed Wheels

38, 40. The yieldable area contacts are obtained by the provision of treads or

tires

42, 44 on the rim portion of the

wheels

38, 40 each of which is fabricated of elastomer material. Included among the synthetic and natural materials which are suitable to provide the yieldable rim portions are rubber and neoprene, which may be conveniently coated onto the peripheries of the

roller

38, 40. The biasing effect of the spring 26 of the presser foot bar 24 and the yieldable characteristics of the particular elastomer material employed determines the extent of the area contact with the material M passing over the plate 32. By

appropriate selection and adjustment of these parameters,

more or less area contact can be attained in accordance with operational requirements.

The

feed Wheels

38, 40 are supported for rotation about respective oblique axes through provision of a bracket 46 which is rigidly mounted on the presser foot bar 24. The bracket 46 includes a cross bar 48 from which depend arms 50, 52 which carry respective bearings 54, 56 for journaling of the

wheels

38, 40 for rotation under control of the drive which is to be subsequently described. The cross arm or bar 48 carries a socket member 58 which is provided with a forwardlyopening seat 60 which has a cross section selected to conform to the lower end 24a of the presser foot bar 24 and to embracingly engage the same. As seen best in Fig. 5, the socket member 58 is provided with a hole 62 which is alignable with a threaded hole 64 in the fiat 24b on the lower end 24a of the presser foot bar 24, the aligned holes 62, 64 receiving an attachment screw 66. Spaced below the location of the attachment screw 66, the socket member 58 is provided with a threaded hole 68 which receives an adjustment screw 70 having a forward end in bearing contact with the flat 24b of the presser foot bar 24. Clearance is provided between the opening 62 and the shank of the attachment screw 66 so that the

screws

66, 70 may be employed for adjustably suspending the

feed wheels

38, 40 for a range of adjustment fore and aft of the needle 30. For example, the wheels may be translated forwardly in relation to the needle 30 by drawing back on the adjustment screw 70 and tightening down on the attachment screw 66. The required range of adjustment is a comparatively small one, being of the order of ,4, of an inch; the disclosed means is adequate to provide the necessary range of adjustments so that the effective work-engaging regions (the continuous flattened portion presented at the darning plate 32) may be appropriately positioned in relation to the needle 30.

Operatively connected to the

feeding wheels

38, 40 are respective drives for continuously rotating the feed wheels in contact with the feed bed or plate 32 with the material M interposed therebetween. As detailed in my earlier filed application Serial No. 416,900 of March 17, 1954 (now U.S. Patent No. 2,777,409) the drive for the

wheels

38, 40 may be obtained without material modification of the standard sewing machine. A bracket 72 is secured to the machine table at a location rearwardly of the hand wheel 22 at the drive end of the machine. The bracket supports a pivoted arm 74 on which is mounted a pulley 76. Disposed in coplanar relation to the pulley 76 is a further pulley 78, the aligned pulleys being coupled together by an appropriate drive 80. Belt tension is obtained by a spring (not shown) which is connected between the pivoted arm 74 and the bracket 72 and biases the pulley 76 away from the pulley 78. In order to provide an effective-selection means, the pulley may be constructed of two side by side pulling-forming elements 82, 84 having opposed conical belt-engaging faces. The pulley-forming elements 82, 84 may be adjusted toward and away from each other to vary the effective pulley diameter and the rate of the

feed wheels

38, 40. Attachment of the pulley 78 to the main drive shaft of the machine requires no change in the machine construction and merely necessitates the removal of the machine component normally found at this location. For further details of the variable speed drive means, reference should be made to the aforesaid copending application.

Individual driving connections are provided between the driven pulley 76 and the

respective feed wheels

38, 40. Specifically coupling cables 86, 88 extend from the pulley 76 to the

respective wheels

38, 40. The cables 86, 88 are disposed within

appropriate sheaths

90, 92. Each cable 86, 88 has one end geared to the pulley 76, by gearing (not shown), but arranged to continuously drive the

wheels

38, 40 in directions appropriate to feed the material M past the needle. The details of the gearing may be found in my issue Patent No. 2,741,197. The cable or coupling 86 carries a pinion 94 which meshes with a worm gear 96 fixed to the wheel 38; similarly the cable 88 carries a pinion 98 which meshes with a worm gear 100 carried by the wheel 40. The described coupling arrangement is effective to turn the

wheels

38, 40 in the same direction and at the same speed, which speed is determined by the adjustment of the speed-selection means.

The assembly to be stitched is engaged by the

feed wheels

38, 40, both of which are yieldably urged against the .plate 32 by the action of the presser foot bar spring 26. The yieldable rims 42, 44 flatten out under the pressure of the spring 26, which if neededmay be supplemented by the addition of a further spring, to present fiat rolling contacts against the material at a rate dependent upon the drive of the

respective feed wheels

38, 40. p v

In the form of the invention illustrated in Figs. 1 to 6, the

feed wheels

38, 40 are outwardly inclined relative to each other symmetrically of a vertical plane through the needle and coinciding with the stitch line. The degree of outward inclination is selected such that the conical workengaging surfaces are disposed to contact the plate 32. Further the axes of the

feed Wheels

38, 40 are disposed in relation to the needle so that the contact region begins at the needle 38 and extends rearwardly-thereof. As seen in Fig. 6, the flattened work-engaging surfaces or

workcontact areas

102, 104 extend from the needle 30 and diverge slightly in relation to each other and relative to the plane of symmetry of the feed wheels 38, '40. In practice it has been found that the diverging work-

contact areas

102, 104 afiorded by the rolling contact of the

wheels

38, 40, are efiective to laterally tension the material M during its passage through the stitching zone which includes the needle 30. It has been found that this lateral tension or stretching, materially reduces, and in many instances substantially eliminates, the tendency of the material M to pucker or gather as a result of the stitching operation. It is presently thought that the lateral tensioning is effective, much like tensioning along the stitch line, to keep the material from gathering as a mal divergence which the workcontacting areas R1 02, have as a result of the initial outward inclination of the work-engaging or contacting areas 102", 104" which con-' verge rearwardly of the needle. This arrangement of the feed wheels has been found to be particularly suitable for the stitching of multiple-ply assemblies in accordance with the teachings of United States Patent No. 2,741,197

of April 10, 195.6.

A typical cycle of operation and contemplated ad:

justrnents will be described in order to facilitate a more thorough understanding of the present invention:

The presser foot of the conventional sewing machine is removed and replaced by the rotary attachment 36; and the conventional feed dog and throat plate are re-- moved and replaced by the darning plate 32 which preferably has the curved plateau 106. The rotary feed attachment 36 may be raised and lowered relativeto the darning plate just as the presser foot was raised and lowered by manipulating the conventional presser foot lever on the sewing machine.

The operator obtains therequisite top feed of the material by adjusting the speed selection means and the continuous rotary contact against the feed. plate. The

yieldable rotary contact and the fiatplate are effective to feed the material under tension and with minimum risk of marring soft materials, which is a pronounced problem when using a conventional feed dog having teeth in engagement with the under surface of the material. The

result of the spring back of the top thread when the same is relieved of tension after stitching. Although the theory of this operation has not been completely verified, it is thought that the provision for maintaining the material taut across the stitch path avoids distortion along the stitch line.

In accordance with a further aspect of the invention, I have found that the eifective work-contacting areas 102 104 may be increased by the use of a specially-constructed darning plate 32 having a plateau orelevation 106 rearwardly of the needle. The plateau 106 is constructed with a curvature and elevation to conform to a portion of the periphery of the

feed wheels

38, 40 to thereby effectively elongate the areas of

contact

102, 104 as compared to the contact afiorded by the use of a flat plate 32. Although the specially constructed plate 32 is preferred, it is not esesntial for the operation of the

feed wheels

102, 104 in accordance with the present invention.

When working with certain types of materials and threads, it may be desirable to have the Work-contact,

regions

102, 104 diverge at a greater angle relative to each other behind the needle 30 to thereby exert a greater amount of lateral stretch on the material M as it passes from the needle rearwardly along the stitch'line. This may be achieved, as illustrated in Fig. 7, by toeing the

feed wheels

38, 40 outwardly in a direction rearwardly of the needle and in relation to the plane ofsymmetry passing along the stitch line and in the vertical plane of the needle whereby

area contacts

102, 104 are providedwhich have a more pronounced divergence. It will be appreciated that the toeing out of the feed wheels in a direction rearwardly of the needle supplements the norattachment may be rocked fore and aft of the needle and fixed in any required position of adjustment by rnanipulation of the attachment and adjusting screws as previously detailed. Further, the disposition of the respective work contact areas may be altered in relation to each other by changing the position of the feed wheels with respect to the plane of symmetry. Still further, the

length of the work contact areas may be increased by the use of specially constructed darning plates having various elevations.-

In use, it is merely necessary for the operator to ad- Vance the goods to the needle as is required in handling an ordinary sewing machine. The operator is not required to exercise individual judgment and no special skill is expected of the operator to provide'acceptable seams.

Although the present invention has been described with specific reference to single needle machines, it will be appreciated that the present feed attachment may be arranged at opposite sides of a two-needle machine;

Although there has been described a specific embodiment of the invention, a range of alternatives, modifications,'omissions and additions should be readily apparent to those skilled in the art. It is accordingly appropriate that the appended claims be accorded a latitude of interpretation consistent with of the invention.

What I claim is:

l. A rotary feed attachment for a sewing machine stroke through said needle hole and operatively connected to said main drive comprising a pair of feed Wheels journaled for rotation at opposite sides of said needle and each having a conical work-engaging surface, said feed the spirit and scope.

wheels being outwardly inclined relative to each other whereby said conical work-engaging surfaces are positioned -to contact said abutment portions of said plate, the conical work-engaging surfaces of said feed wheels being fabricated of yieldable material and so constructed and arranged as to be yieldably engaged against said plate to flatten and to provide area contacts against material to be fed over said plate and past said needle, and means adapted to operatively connect said pair of feed wheels to said main drive.

2. .A rotary feed attachment for a sewing machine having a main drive, a plate having a needle hole and a needle movable in a stitch-forming stroke through said needle hole and operatively connected to said main drive comprising a pair of feed wheels journaled for rotation at opposite sides of said needle and each having a conical work-engaging surface, said feed wheels being outwardly inclined relative to each other whereby said conical work-engaging surfaces contact said plate, the conical work-engaging surfaces of said feed wheels being fabricated of yieldable material and arranged so as to be yieldably engaged against said plate to provide area contacts against said plate with material to be fed over said plate and past said needle, said feed wheels being toed outwardly rearwardly of said needle whereby said area contacts diverge rearwardly of said needle and maintain said material in tension behind said needle, and means operatively connecting said pair of feed wheels to said main drive.

3. A rotary feed attachment for a sewing machine having a main drive, a plate having a needle hole and abutment portions arranged at opposite sides of said needle hole, a needle movable in a stitch-forming stroke through said needle hole and operatively connected to said main drive and a presser foot bar, said attachment comprising a pair of feed wheels, means operatively connected to said presser foot bar arranged to journal said feed wheels for rotation at opposite sides of said needle, each of said feed wheels having a conical work-engaging surface, said feed wheels being outwardly inclined relative to each other whereby said conical work-engaging surfaces are disposed to contact said abutment portions of said plate, the conical work-engaging surfaces of said feed Wheels being fabricated of yieldable material and arranged relative to said plate so as to be yieldably engaged against said plate to flatten and to provide area contacts against said plate extending from said needle rearwardly of said plate, said area contacts being spaced apart and diverging rearwardly and outwardly of said needle to grip material therebetween and to laterally tension "the material, and means operatively connecting said pair of feed wheels to said main drive.

4. A rotary feed attachment according to claim 3 wherein the means journaling said feed wheels on said presser foot bar are constructed and arranged to facilitate adjustment of said feed wheels relative to said needle.

5. A rotary feed attachment for a sewing machine having a main drive, a plate having a needle hole and abutment portions arranged at opposite sides of said needle hole, a needle movable in a stitch-forming stroke through said needle hole and operatively connected to said main drive and a presser foot bar, said attachment comprising a pair of feed wheels, mounting means operatively connected to said presser foot bar arranged to journal said feed wheels for rotation at opposite sides of said needle, said mounting means including a bracket carrying said feed wheels and attachment members selectively engaging said presser foot bar for adjustably suspending said feed wheels from said presser foot bar, each of said feed wheels having a conical work-engaging surface of yieldable material, said feed wheels being outwardly inclined relative to each other whereby said conical work-engaging surfaces are disposed to contact said abutment portions of said plate, the conical work-engaging surfaces of said feed wheels being yieldably engaged against said plate to flatten and to provide area contacts against said plate extending from said needle rearwardly of said plate, said area contacts being spaced apart and gripping material therebetween to laterally tension the material, and means operatively connecting said pair of feed wheels to said main drive.

6. A sewing machine including a plate over which Work is fed having a needle hole and including abutment portions at the opposite sides of said needle hole, at least one needle operatively disposed relative to said plate and movable through said needle hole in a. stitchforming stroke, rotary feed means cooperating with said plate for advancing the several layers of a multiple-layer assembly to be sewn past said needle, said rotary feed means being operative at both sides of said needle and including a pair of feed wheels straddling said needle and having work-contact areas rearwardly of said needle, each of said feed wheels including a rim of elastomer material flattened against said abutment portions and adapted to present successive flattened work-contact areas in response to rotation of said feed wheels, and means operatively connected to drive said rotary feed means.

7. In combination with a sewing machine having a drive, a needle movable through a stitching-forming stroke and operatively connected to said drive, and a plate over which material moves past said needle and including abutment portions at opposite sides of said needle, a pair of rotary feed wheels disposed at opposite sides of said needle and contacting said abutment portions, said rotary feed wheels being constructed to provide yieldable work-engaging faces at opposite sides of said needle, the work-engaging faces of said feed wheels being positioned relative to said plate to make area contact with said plate, said work-engaging faces being flattened against said abutment portions and being effective to advance an assembly to be sewn past said needle, and means operatively connecting said feed wheels to said drive.

8. In combination with a sewing machine having a drive, a needle movable through a stitching-forming stroke and operatively connected to said drive, and a darning plate over which material moves past said needle and including abutment portions at opposite sides of said needle, a pair of driven rotary feed wheels disposed at opposite sides of said needle and contacting said abutment portions, said rotary feed wheels having yieldable rims providing work-engaging faces at opposite sides of said needle, the yieldable work-engaging faces of said feed wheels being flattened into area contact with said plate and being effective to advance an assembly to be sewn past said needle.

9. In a sewing machine, a feed bed, a needle, a presser foot bar, a spring urging said presser foot bar downwardly toward said feed bed, a pair of oblique shafts operatively connected to said presser foot bar, a conically-faced feed wheel having a yieldable work-engaging face journaled on each of said oblique shafts, said feed wheels being in transverse alignment with and on opposite sides of said needle, successive peripheral portions of said work-engaging faces being flattened against said feed bed by said spring during rotation of said feed wheels whereby work passing over said feed bed beneath said feed wheel is pulled past said needle, said feed wheels being toed out rearwardly of said needle whereby the work-engaging faces stretch the work behind said needle, and means for rotating said feed wheels.

10. In a sewing machine, a feed bed including spaced abutment portions, a needle, a presser foot bar, a spring urging said presser foot bar downwardly toward said feed bed, a pair of oblique shafts operatively connected to said presser foot bar, a conically-faced feed wheel having a yieldable work-engaging face journaled on each of said oblique shafts, said feed wheels being in transverse alignment with and on opposite sides of said nee- 9 dle and contacting said abutment portions, successive peripheral portions of said work-engaging faces being flattened against said feed bed by said spring during rotation of said feed wheels whereby work passing over said feed bed beneath said feed wheels is pulled past said needle.

11. In a sewing machine, a feed bed including spaced abutment portions, a needle, a presser foot bar, a spring urging said presser foot bar downwardly toward said feed bed, a pair of oblique shafts operatively connected to said presser foot bar, a conically-faced feed wheel having a yieldable work-engaging face journaled on each of said oblique shafts, said feed wheels being in transverse alignment with and on opposite sides of said needle and contacting said abutment portions, successive peripheral portions of said work-engaging faces being flattened against said feed bed by said spring during rotation of said feed wheels whereby work passing over said feed bed beneath said feed wheels is pulled past said needle, said feed bed including a portion rearwardly of said needle curved to conform to said work-engaging faces.

12. In combination with a sewing machine having a drive, a needle movable through a stitching-firming stroke and operatively connected to said drive, and a a) plate over which material moves past said needle, a pair of rotary feed wheels disposed at opposite sides of said needle, said rotary feed wheels being constructed to provide yieldable work-engaging faces at opposite sides of said needle, the work-engaging faces of said feed wheels being positioned relative to said plate to make area contact with said plate and being effective to advance an assembly to be sewn past said needle, said plate having an elevated portion rearwardly of said needle having a curvature selected to conform to said work-engaging faces of said feed wheels and arranged to contact said feed wheels to enlarge the effective area contact which each of said feed wheels makes with said plate, and means operatively connecting said feed wheels to said drive.

References Cited in the file of this patent UNITED STATES PATENTS 735,641 Wilson Aug. 4, 1903 1,069,836 Wieczoreck Aug. 12, 1913 2,317,762 Hale Apr. 27, 1943 2,741,197 Winberg Apr. 10, 1956 FOREIGN PATENTS 413,519 France Aug. 11, 1910 430 Great Britain of 1865