US2965056A

US2965056A - Sewing machines

Info

Publication number: US2965056A
Application number: US674150A
Authority: US
Inventors: Ned L Wallenberg; John F Hopp
Original assignee: Union Special Machine Co
Current assignee: Union Special Machine Co
Priority date: 1957-07-25
Filing date: 1957-07-25
Publication date: 1960-12-20
Anticipated expiration: 1977-12-20
Also published as: GB835386A

Description

Dec. 20, 1960 N. L. WALLENBERG ETAL 2,965,056

SEWING MACHINES 9 Sheets-Sheet 1 Filed July 25, 1957 N. WALLENBERG r AL 2,965,056

Dec. 20; 1960 SEWING MACHINES Filed July 25, 1957 Y 9 Sheets-Sheet 2 Dec. 20, 1960 N. L. WALLENBERG ETAL 2,965,056

SEWING MACHINES Filed July 25, 1957 9 Sheets-Sheet 3 FIG.3

Dec. 20, 1960 Filed July 25, 1957 N. L. WALLENBERG EI'AL SEWING MACHINES 9 Sheets-Sheet 4 Dec. 20, 1960 N. WALLENBERG ETAL 2,965,056

SEWING MACHINES Filed July 25, 1957 9 sheets sheet 5 2. QE w Ema -imm Dec. 20, 1960 N. L. WALLENBERG ETAL 2,965,056

' SEWING MACHINES Filed July 25, 1957 9 Sheets-Sheet 6 Dec. 20, 1960 N. L. WALLENBERG ETAL SEWING MACHINES Filed July 25, 1957 9 Sheets-Sheet 7 FIG.9

Dec. 20, 1960 N. L. WALLENBERG ETAL 2,965,056

SEWING MACHINES Filed July 25, 1957 9 Sheets-Sheet s FIQJI Dec. 20, 1960 N. L. WALLENBERG ETAL 2,965,056

SEWING MACHINES Filed July 25, 1957 9 Sheets-Sheet 9 SEWING MACHINES Ned L. Wallenberg, hicago, and .iohn F. Hopp, Northbrook, Ill., assignors to Union Special Machine Company, Chicago, 111., a corporation of iilinois Filed July 25, 1957, Ser. No. 674,150

Claims. (Cl. 112-208) This invention relates to sewing machines having differential feed mechanism. It is particularly useful in such machines which are adapted to produce a shirring or similar effect by advancing one work piece or member, entering into a finished product, at a faster rate than the normal feed of the work as a whole in the region of stitch formation. However, it should be understood that the invention is of broader application.

In machines of the character to which the present invention is directed there are usually provided a plurality of feed bars each carrying a feed dog. One feed bar carries a main feed dog which operates to advance the work in the region of stitch formation at a rate which determines the stitch length. Another feed bar, closely adjacent to and parallel with the first, carries an auxiliary or differential feed dog which is usually arranged to advance the work, or one or more layers of multi-layer work, toward the stitching zone, at a rate which may be less than, equal to, or greater than the stitch length determining rate of the main feed dog. This may be done for any of a variety of purposes. The provision of a greater differential feed action may be provided simply to prevent undue stretching of work formed of stretchable material in advance of the stitching point, or it may be provided to produce a shirring or ruflling effect, on the work as a whole or one one or more layers of multi-layer work. It has been found that feed mechanisms of this character, as heretofore constructed, have frequently been limited in the extent of differential action permitted between the two feed dogs, due to interference between portions of the operating connections. Mechanisms as heretofore constructed in an effort to overcome this difiiculty have been complicated and cumbersome and have required an excessive amount of space.

A primary object of the present invention has been to provide a simple, lightweight and compact mechanism for operating a main and a dilferential feed dog at rates which may vary relative to each other over a wide range without encountering the difliculties of interference between the several moving parts. The improved arrangement devised for this purpose enables the positioning of the two feed bars, which carry the separate feed dogs, in close side-by-side relation and enables the positioning of a pitman for driving the main feed bar and a link for operating the differential feed bar in the same vertical plane without the necessity of complicated configuration of either and without requiring cumbersome driving connections to prevent interference. This is in part achieved by arranging two pitmans to extend in opposite directions from eccentrics on the drive shaft for operating two feed bars. It involves also a direct connection between one of these pitmans and the main feed bar.

In conjunction with the foregoing the invention provides means for changing the extent of feed action of the difierential feed dog in the course of operation of the machine. Simple means are also provided for predetermining two definite differential feed actions involving two predetermined rates of feed, which may be selected atent O F 2,965,056 Patented Dec. 20, 1950 at will by the operator in the course of a seaming operation. Selection of one or the other of the two rates may be controlled by the operation of a treadle or a knee press. This is desirable, for example, in the seaming of Work which it is desired to shirt in certain sections and leave fiat in other sections. Provision is made, in this connection, for shirring an under layer of two work pieces while the top layer is advanced smoothly, without shirring. Such shirring may be carried out for all or any desired portion or portions of a complete seam. Provision may also be made for the incorporation of a binder and a cord into the seam whenever desired. The mechanisms for accompiishing these purposes are of simple construction and readily thrown into and out of operation.

Other objects, features and advantages of the invention will appear from the detailed description of an illustrative embodiment of the same which will now be given in conjunction with the accompanying drawings, in which:

Fig. l is a front elevational view of an overedge sewing machine embodying the invention;

Fig. 2 is a transverse, sectional view through the machine taken along the line of stitch formation and looking toward the right;

Fig. 3 .is an enlarged detail view showing, in side elevation, the feed dog actuating mechanism;

Fig. 3A is a further enlarged detail view, taken from the opposite side of Fig. 3, showing one form of the feed bars and their supporting means;

Fig. 4 is a plan view of the work supporting portion of the machine with the cloth plate removed;

Fig. 5 is a vertical, sectional view taken along the line 55 of Fig. 4;

Fig. 6 is an exploded, perspective view of the feed dog carrying and actuating mechanism of the machine;

Fig. 7 is a vertical, sectional view through a portion of the feed mechanism taken along the line 7-7 of Fig. 4;

Fig. 7A is a top view of a throat plate embodied in the machine;

Fig. 8 is a view, largely in side elevation but partly in transverse section, showing the action of the main and differential feed dogs;

Fig. 9 is a plan view of portions of the machine showing a shirring attachment applied thereto in operative position;

Fig. 10 is a plan view of a portion of the machine showing the shirring attachment swung into an inoperative position;

Fig. 11 is a detail view of the machine;

Fig. 12 is a front, elevational view of the shirring attachment and a supporting bracket therefor;

Fig. 13 is an elevational view of the parts shown in Fig. 12 as seen from the right of the latter;

Fig. 14 is an elevational view of the parts shown in Fig. 12 as seen from the left of the latter;

Fig. 15 is a plan view of a portion of the machine showing a binder guide and cord guide embodied in the machine in association with the shirring attachment;

Fig. 16 is a vertical, sectional view on an enlarged scale taken along the line 16-16 of Fig. 15;

Fig. 17 is a bottom view of the presser foot embodied in the machine; and

Fig. 18 is an elevational view of the presser foot and presser arm as viewed from the rear of an edge guide employed in a portion of a the machine.

The invention has been shown as applied to an overedge sewing machine of the general type disclosed in the patents to Peterson et al., No. 2,636,462, granted April 28, 1953; Wallenberg et al., No. 2,704,042, granted March 15, 1955; and Schoij, et al., No. 2,730,060, granted January 10, 1956. Reference may be had to said patents for details of construction of suitable stitch forming devices which may be embodied in the machine and vention, as indicated above, is concerned primarily with improvements in the construction and arrangement of the various parts of the work feeding mechanism and cooperating attachments for controlling the advance of the work to and past the stitch forming zone. In the following description only these improved features will be described in detail.

Referring now to Fig. 1, the illustrative machine is provided with a main frame providing an enclosed housing for the main operating devices of the machine. A top member 10a of the frame serves as a closure for the top thereof and as a support for various devices. A bottom plate 11 closes the bottom of the frame 10 and is arranged to support the machine upona table or the like. Within the main frame 10 of the machine there is suitably journaled a main drive shaft 12 (Fig. 6) which extends longitudinally of the frame. This shaft extends outwardly from the frame at its right end (Fig. 1) and carries a combined hand wheel and pulley 13 through which power may be supplied to the machine. The top member 10a of the frame carries a longitudinally extending arm 14 which serves as a support for the spring means acting upon a presser arm, as will be later explained. An extension at the left end of the main housing 10 (Fig. 1) carries a cloth plate 15 over which the work being stitched is passed.

The details of the stitch forming devices are not disclosed herein since, as indicated above, they may suitably be of the character disclosed in one or more of the specified prior patents. .In Fig. 1 there is simply shown a curved needle 16 arranged to be passed downwardly through the work on the cloth plate 15. It will be understood that suitable under and overedge loopers cooperate with the needle 16 to produce the desired overedge stitch.

Likewise reference should be had to the above-mentioned patent to Wallenberg et al. for a fuller disclosure of suitable edge trimming mechanism which may be incorporated in the machine. It is believed suflicient to note for the purpose of the present invention that such mechanism is contemplated and involves the provision of a stationary blade 17 (Fig. 1), suitably mounted on a portion of the frame beneath the work supporting surface, and a movable blade 18 carried by a head 19 at the end of a rock arm arranged to be driven by suitable connections from the main drive shaft 12.

Turning now to the work feeding mechanism of the machine, this comprises a main feed dog 20, a differential feed dog 21 and a chaining dog 22 (Fig. 2). It will he understood that the chain feed dog is arranged to cooperate with the thread chain formed by the successive items being stitched to assure the proper advance of the chain and the application of a desired tension thereto.

The main feed dog (Figs. 2 and 3) is provided with a shank having a vertically elongated opening 23 with which cooperates a screw 24 by which this feed dog may be secured to a main feed bar 25. Preferably this feed bar is provided with a vertical channel 24a adjacent its forward end to receive the shank of the feed dog. By the arrangement described it will be apparent that the position of the main feed dog may be adjusted slightly in a vertical direction to suit the particular requirements of the work to be performed. By adjusting the elevation of the feed dog the period in each cycle during which it is effective in advancing the work may be increased or decreased, thus varying slightly the resulting stitch length.

Similarly, the differential feed dog 21 is provided with a shank having a vertically elongated slot 26 with which cooperates a screw 26a by which it may be secured to the forward end of an auxiliary or differential feed bar 28 (Fig. 6). If desired, this feed bar may also be provided with a vertically disposed channel 27 to receive the shank of the feed dog 21 and, as will be apparent, the elevation of the differential feed dog may be adjusted slightly in the same manner as the main feed dog. The

. lowering movements of the main feed bar.

chaining dog 22 has a shank adapted to be secured by a screw 29 to the main feed bar 25 in a position slightly in rear of the main feed dog and directly along the path of stitch formation. An elongated opening 30 in the feed bar 25 enables slight vertical adjustment of the chain feed dog. The latter, it will be understood, is provided with a screw threaded opening to receive the threaded end of the screw 29 to secure the feed dog to the feed bar. Preferably, also, the chain feed dog is pro vided with a vertically extending rib 31 arranged to extend into a guide channel in the face of the feed bar 25 opposite that shown in Fig. 3.

The main feed bar 25 is provided with a recess or slot 32 in its rearward end (Figs. 2 and 6) with which cooperates a rectangular block 33 carried by an eccentric stem portion 34 (Fig. 4) of a stud 35 carried by the frame of the machine. The arrangement is such that by turning the stud 35 the elevation of the block 33 may be varied slightly to lift or lower the rearward end of the feed bar. A set screw 36 may be provided to lock the stud 35 in any set position. At its forward end the feed bar 25 is provided with a downwardly and rearwardly extending portion 37 providing a guide opening or slot 38 adapted to receive a guide block 39 (Fig. 6). The latter is mounted on an eccentric portion 40 of the shaft 12 which serves to impart the desired lifting and lowering movements to the forward end of the feed bar.

In a similar manner the differential feed bar 28 is provided with a guide slot or opening 41 at its rearward end arranged to cooperate with a block 42 carried by the eccentric stem 34 of the stud 35. This enables the necessary pivotal movements of the feed bar about its rear supporting means. Adjacent its forward end the feed bar 28 is provided with a flat undersurface 43 positioned slightly below the main body of the feed far, this surface being adapted to ride upon the top of the guide block 39 and thus partake of the up and down movements of the latter. Also, the feed bar 28 is provided with a screw stud 44 having an unthreaded main portion arranged to carry a guide block 45 adapted to cooperate with a guide slot 46 formed through the feed bar 25. A sleeve 47 is interposed between the opening in the guide block 45 and the shank of the stud 44. Also a hollow stud 48 is interposed between the sleeve 47 and the stud 44. To retain the block 45, sleeve 47 and hollow stud 48 on the screw stud 44 along with certain other parts to be described, there is provided a nut 49. It will be seen that by virtue of the connections described the lifting and lowering movements of the forward end of the main feed bar 25. due to the action of eccentric 40, will be transmitted to the differential feed bar 28.

In Figs. 3A and 7 there is disclosed a dilferent arrangement for supporting the forward end of the differential feed bar and causing this to partake of the lifting and In this construction the main feed bar 25a is provided with a laterally extending shelf-like portion 51 upon which the differential feed bar 28a rests and slides. To retain the differential feed bar against the shelf 51 there is provided a block 52 secured to the main feed bar by a screw 53. As best shown in Fig. 7, the arrangement is such that the elevation of the block 52 may be varied slightly to provide desired clearance for a good sliding fit of the differential feed bar between the block and the shelf 51.

The means for imparting feed and return movements to the two feed bars will now be described. For the purpose of driving these feed bars the main shaft 12 is provided adjacent its left end (Figs. 6 and 7) with an eccentric portion 54 having a spline 54a (Fig. 7). On the portion 54 of the shaft there is mounted an eccentric 55 adapted to drive the main feed bar. The arrangement is such, as shown in Fig. 7, that the eccentric 55 partially offsets the eccentricity of the portion 54 of the shaft 12. The arrangement is such that different eccentrics 55 may be used, one in place of the other, to vary the overall eccentricity which determines the feed stroke imparted to the main feed bar. For a relatively long feed stroke the eccentric 55 may be replaced by a concentric ring or by an eccentric serving to add to the eccentricity of the portion 54 of the shaft. A pitman 56 has a strap portion 57 (Fig. 6) cooperating with the eccentric 55 and has an opening 58 adjacent its forward end adapted to fit snugly over a pin 59 projecting laterally from the main feed bar. It will be apparent that through the connections described the main feed bar will be given feed and return movements determined by the overall eccentricity of portion 54 of the shaft 12 and the eccentric element 55. To retain the pitman 56 on the pin 59, and also to retain the pitman and the two feed bars in their proper planes with an appropriate sliding fit, a guide block 59a is secured to the frame of the machine and arranged to cooperate with the outer face of the pitman.

For driving the differential feed bar a somewhat more complicated arrangement is provided to enable variation of the feed stroke of the differential feed bar, and the arrangement is such that this may be done in the course of operation of the machine. The means for driving the differential feed bar comprises an eccentric element 66 mounted on the portion 54 of the shaft 12 and having a keyway cooperating with the spline 54a. As best shown in Fig. 7, the eccentric 60 adds to the eccentricity of the portion 54 of the shaft 12. A pitman 61 has a strap portion 62 surrounding the eccentric 60 and an opening 63 at its opposite end arranged to cooperate with a sleeve 64 mounted on a screw stud 65 carried by a rocker member 66. A nut 67 serves to retain these parts in assembled relation. Similarly, a nut 63 serves to retain the

eccentrics

55 and 66 on the shaft 12. Rock member 66 is mounted on a fixed shaft or stud 69 (Fig. 3) and it is provided with a segment-like portion having an arcuate slot 70. The latter is adapted to receive a block 71 secured by a screw 72 to an intermediate hub portion 73 of a link 74. The latter at its forward end has a hub portion 75 arranged to cooperate with an enlarged portion of the hollow pin 48 previously described. The nut 49 serves to retain the hub 75 in assembled relation with the other parts shown aligned therewith in Fig. 6. It will be seen that through the connections described rocking movements imparted to the member 66 by the eccentric 60 through the link 61 will be transmitted to the differential feed bar through the link 74 and the screw stud 44.

The extent of movement of the differential feed bar will be determined by the position of the block 71 along the arcuate slot 70. When the block is adjacent the upper end of this slot at maximum forward stroke will be imparted to the differential feed bar, this being greater than the throw of the eccentric 60. When the block is shifted to the lower end of the slot 70, a minimum or no movement will be imparted to the differential feed bar. In fact, the direction of the movement could be reversed if desired.

For the purpose of varying the feed stroke of the differential feed bar during operation of the machine, means are provided for shifting the block 71 by suitable connections from a treadle or knee press. Thus the link 74 is provided with a rearwardly extending arm 76 having a screw threaded opening arranged to receive a screw 77 which serves to pivotally connect the upper end of a link 78 with the arm 76. The lower end of link 78 is connected pivotally with the forward end of a two-armed lever 79 by means of a screw 80. The two-armed lever 79 is pivotally mounted on a screw stud 81 which extends through an opening in a supporting bracket 82 suitably secured to the frame of the machine. A nut 81a cooperating with the stud 81 serves to secure the latter to the bracket. A spring 83 surrounding a hub 84 on the lever 79 has one end engaged over the forwardly extending arm of the latter and its other end engaged over a rearward portion of the bracket 82. This arrangement is the lower end of the arcuate slot 70. This will tend to shorten or eliminate the feed stroke of the differential feed bar. The rearwardly extending arm of the lever 79 is provided with an opening 85 adapted to be connected by a chain or rod or the like to a treadle or knee press in a well-known manner. By operation of the treadle or knee press the lever 79 will be rocked in a counterclockwise direction and may assume the position shown in Fig. 3. This will provide maximum feed stroke for the differential feed bar.

To enable the lever 79 to be readily shifted into two definite positions corresponding with two different stitch lengths desired in the courseof operation of the machine, there is provided a pair of stops for limiting the movement of lever 79 in each direction. These stops are provided by pins 86 having screw threaded portions which extend through an elongated slot 87 in the bracket 82 and cooperate with nut elements 88 which serve to lock the pins in any set position. The nut elements are preferably provided with flattened faces, as shown in Fig. 6, to cooperate with the side walls of the opening 87. Washers 89 may be provided between the face of the bracket 82 and the inner ends of the enlarged portions of the pins 86.

It will be noted that there is a slight difference in the connections provided between the link 74 and the differential feed bar as between the form of the invention shown in Figs. 5 and 7 and that shown in Fig. 6. In the first-mentioned form the hub 75 at the end of link '74 cooperates with a cylindrical sleeve 48a retained by the bolt or screw stud 44. A clearance is provided between the Walls of the opening through the feed bar 25a and the sleeve 48a. However, in the construction shown in Fig. 6, the block 45 has a relatively close sliding fit in relation to the top and bottom walls of the opening through the main feed bar and thus serves as a means for insuring concomitant up and down movements of the two feed bars. To retain the pitman 61 in proper cooperation with the eccentric 60, a guide element 90 is provided, this being secured to the frame of the machine and having a finger 90a the end of which cooperates with the adjacent face of the pitman 61 for the purpose indicated.

Cooperating with the main feed dog 20 and the chain feed dog 22 is a presser foot 91 pivotally mounted upon the forward end of a presser arm 92. The latter, as shown in the Peterson et a1. and Wallenberg et a1. patents mentioned above, is adapted to rock about a horizontal axis and is also adapted to be swung outwardly about a vertical axis when access to the mechanism behind it is desired. The presser arm is urged downwardly by suitable spring means contained within a housing 92a in known manner. When the arm is to be swung outwardly a forked portion 92b of a spring-urged element within the housing may be lifted away from the arm by appropriate release means. At its forward end the presser arm has a laterally extending pin 93 which fits in a hollow depression at the top of the presser foot and is retained in the latter by means of a detent 94 carried by the presser foot. This detent may readily be swung about a pivot screw 95 to release the presser foot from the arm. If desired, the presser foot may extend forwardly to a greater extent than shown and cooperate with the differential feed dog 21, or another presser e ement carried by the frame may cooperate with the differential feed dog. However, in the illustrative machine there is shown a shirring attachment which cooperates with the feed dog 21.

The shirring attachment comprises a blade 96 (Figs. 2, 8 to 10, 12 and 14) carried by a rock shaft 97 mounted in an inverted U-shaped bracket 98. Secured to the shaft 97 adjacent the inner face of one of the legs of the bracket is, a, collar 99. A spring 100 surrounding 7 the shaft and having one end coacting with the collar 99 and the other end coacting with the bracket 98 serves to urge the shaft 97 in a counterclockwise direction (Figs. 2 and 14) to hold the rearward end of the blade 96 in cooperative relation to the feed dog 21. Whenever desired the shirring blade may be swung through an arc of about 180 around a vertical pivot to an inoperative position such as shown in Fig. 10. For this purpose the bracket 98 is mounted upon a pivot bolt 101 carried by a bracket 102 secured to the frame of the machine. A screw 103 is provided to determine the proper position of the bracket 98 and blade 96 when these are in their operative position shown in Figs. 2 and 9. The end of this screw engages a portion of the frame to determine the limit of movement of the bracket. A flat spring 104 cooperating with a depression or recess 105 in the face of the bracket 98 serves to retain the bracket in its active position but enables it to be readily shifted out of such position. Spring 104 is carried by a bracket 106 secured to the frame of the machine.

In performing certain types of work it may be desired to shirr a portion of the work during part of a seam forming operation but not during other parts of such operation. To eliminate its shirring action, the blade 96 may be lifted against the action of the spring 104 by the operation of an arm 107 secured to the shaft 97. This arm (Fig. 13), may be connected by a chain 108 with a treadle or knee press. It will be understood that the shirring attachment may be employed to bring about a shirring or rutfling action on the work as a whole when the blade is active or simply upon one or more layers of the work. In the latter case the layer or layers not to be shirred or rufiied, see layer 110, Fig. 8, are led to the presser foot and main feed dog over the blade 96 while the layer or layers to be shirred, see layer 109, Fig. 8, are passed under the blade.

The machine may also be equipped with various guides for directing portions of the work correctly toward the work feeding devices and stitch forming devices. For example, an edge guide 111 (Figs. 9 and 11) may be provided for predetermining the position of the edge of the work as it approaches the work feeding devices. This edge guide has an overturned portion 111a providing a channel between it and the main body of the member to receive the edge of the work. The guide is secured to the frame of the machine by a pair of screws 112 cooperating with elongated slots in the main body of the guide. This allows for suitable adjustment transversely of the direction of feed. When the machine is used to provide a shirring effect on only the under layer 109 of the work, which is passed beneath the shirring blade 96, only this layer will be passed through the channel of the edge guide. The top layer 110 which may form the main body of the garment, for example, will pass over the shirring blade and also above the edge guide.

There may also be provided a binder folder and guide 113. This is provided with a U-shaped channel adjacent its discharge end, formed by an inwardly extending flange indicated at 113a in Fig. 15. The arrangement is such that a strip of binder material in passing through the folder will be folded around the flange 113a and delivered in this folded condition to the main feed dog and the stitch forming devices. Folder 113 is carried by a plate-like support 114 secured by screws 115 to a flat arm 116 pivotally mounted on the bracket 102. For this purpose a screw stud 117 is provided around which the arm 116 may be freely swung. Normally, the arm is urged downwardly into frictional engagement with the top surface of bracket 102 by the action of a spring 118. However, when it is desired to swing the binder attachment outwardly into inactive position, it may be lifted by raising the arm 116 along the stud 117 against the action of spring 118. This will enable the arm to be swung over the top of the screw 101. When in its acuve position the arm 116 may abut against a stop such as a screw 119. By virtue of the elongated slots in the member 114 with which the screws cooperate (Fig. 15) the binder attachment may be adjusted suitably in a direction transverse to the line of feed.

Cooperating with the binder attachment and carried thereby there may be provided a cord delivering guide 120 of tubular form. This is arranged to deliver a rein forcing or stiffening cord into the folded binder strip for incorporation in the seam.

The construction and operation of the machine as a whole will be clear from the foregoing. It should be particularly noted that the work feeding mechanism is such that a wide variation may be made in the feed stroke of the difierential feed bar, and this may be done in the course of operation of the machine. The arrangement is such that this feed bar may be given a stroke equal to, less than, or considerably greater than that of the main feed bar. In this connection it will be noted from Fig. 7 that the throw of the eccentric 60 which operates the differential feed bar is preferably made substantially greater than the throw of the eccentric 55 which operates the main feed bar. Also, it will be noted from Fig. 3 that the motion transmitted to the differential feed bar may considerably exceed the throw of the eccentric 60 when the parts are in the position shown in Fig. 3. Thus the feed stroke imparted to the differential feed bar may be a number of times that imparted to the main feed bar. However, when the block 71 is shifted downwardly along the arcuate slot 70 the movement of the differential feed bar will be reduced and may be eliminated altogether when the block is at or near the lower end of the slot. This wide variation in the feed stroke of the differential feed bar is made possible, without interference between the compactly arranged driving connections for the two feed bars, by virtue of the disposition of the two pitmans 56 and 61 which are arranged to extend in opposite directions from their operating eccentrics. It has been found that in prior constructions involving a compact arrangement of relatively few parts for driving the main feed bar and a differential feed bar disposed in side by side relation it has not been possible to provide for the great variation in the feed stroke of the differential feed bar achieved by the present invention. In attempting to provide for a relatively long feed stroke for the differential feed bar with such prior constructions, while maintaining a given feed stroke for the main feed bar. interference has taken place between certain of the operating parts.

It will also be noted that the improved construction is such that the feed stroke of the main feed bar may be readily changed by simply substituting an eccentric 55 of different throw from that illustrated. Eccentric 55 is readily accessible at the end of the shaft 12 for this purpose. Similarly, the eccentric 60 may be replaced by other eccentrics having a greater or smaller throw. In this way an even wider difference between the throws of the two feed bars may be achieved.

While an illustrative embodiment of the invention has been described in detail, it Will be understood that various changes may be made in the construction and arrangement of the several parts without departing from the general principles and scope of the invention.

What is claimed is:

1. Differential feed mechanism for a sewing machine which comprises a main feed bar, a differential feed bar parallel with and adjacent to said main feed bar, means for supporting the rearward ends of said feed bars for pivotal and sliding movement each in its own vertical plane, a main drive shaft, eccentric means on said shaft arranged to impart lifting and lowering movements to the forward ends of said feed bars, additional eccentric means on said shaft adjacent one side of said feed bars, a pitman cooperating with said additional eccentric means and extending substantially horizontally toward the front of the machine, said pitman being connected at its forward end directly with said main feed bar for imparting feed and return movements thereto, a second pitman cooperating with said additional eccentric means and extending substantially horizontally toward the rear of the machine in a plane adjacent that of the first-mentioned pitman, and connections from the rearward end of said second pitman to said differential feed bar for imparting feed and return movements thereto, a portion of said connections being in at least one of the planes containing said first-mentioned pitman and said main feed bar, said connections having relatively adjustable parts enabling the stroke of said diiferental feed bar to be varied over a wide range in relation to that of said main feed bar, including strokes which are either substantially greater or substantially less than that of said main feed bar.

2. A differential feed mechanism of the character set forth in claim 1 in which said connections having relatively adjustable parts comprise a rock member connected directly with said second pitman for rocking movement thereby, a link connecting said rock member with said differential feed bar, and means for varying the point of connection of said link with said rock member toward and away from the axis about which said member rocks, said link being disposed substantially parallel with said differential feed bar when said point of connection is in its most remote position in relation to said axis.

3. A differential feed mechanism of the character set forth in claim 2 in which said rock member extends upwardly from a pivot having a horizontal axis and is provided with an arcuate slot extending upwardly from substantially the horizontal plane through said axis, and said link carries an element at one end thereof arranged to be shifted to different positions along said slot.

4. A differential feed mechanism of the character set forth in claim 1 in which said main feed bar cooperates directly with said first-mentined eccentric means for imparting litfing and lowering movements to said main feed bar, and in which said differential feed bar is so connected with said main feed bar as to partake of the lifting and lowering movements of the latter but is free to move longitudinally in relation to the main feed bar.

5. In combination with a differential feed mechanism of the character set forth in claim 1, a feed dog carried by each of said feed bars, the feed dog carried by the differential feed bar being in advance of the feed dog carried by the main feed bar, a presser foot cooperating with the feed dog on the main feed bar, and a shirring blade disposed above and spring urged into cooperation with the teeth of the feed dog on the differential feed bar.

6. A combination of the character set forth in claim 5 in which a bracket is provided on the sewing machine for swinging movement about a vertical axis, said shirring blade being carried by said bracket and arranged to be swung with the latter into and out of operative position.

7. A combination of the character set forth in claim 6 in which a rock shaft is mounted in said bracket for supporting said shirring blade, a spring for turning said rock shaft to urge said blade into engagement with said feed dog carried by the differential feed bar, and an arm secured to said rock shaft arranged for operation at will to carry said blade away from said feed dog.

8. A combination of the character set forth in claim 6 in which a fixed support is provided on the machine for pivotally supporting said bracket, an arm carried by said fixed support, and a binder folder carried by said arm and arranged to guide and direct a binder tape into cooperation with said feed dog carried by the main feed bar.

9. A combination of the character set forth in claim 8 in which a vertical pivot is provided on said support for said arm whereby the latter is arranged for swinging movement about said vertical pivot to carry said folder into and out of operative position.

10. A combination of the character set forth in claim 9 in which a guide is carried by said folder for delivering of a cord into cooperation with the tape folded by said folder at a point in advance of the feed dog carried by said main feed bar.

References Cited in the file of this patent UNITED STATES PATENTS Re. 24,005 Knaus et al. May 17, 1955 2,659,330 Knaus Nov. 17, 1953 2,662,494 Seaman et al. Dec. 15, 1953 2,669,205 Hayes Feb. 16, 1954 2,711,144 Jullie June 21, 1955 2,751,867 Washburn et al. June 26, 1956