US2966810A

US2966810A - Two-speed drives for sewing machines

Info

Publication number: US2966810A
Application number: US768311A
Authority: US
Inventors: Frank A Hayes
Original assignee: SMGER Manufacturing Co
Current assignee: SMGER MANUFACTURING Co
Priority date: 1958-10-20
Filing date: 1958-10-20
Publication date: 1961-01-03
Anticipated expiration: 1978-01-03
Also published as: GB864745A; FR1238128A; ES252614A1

Description

Jan. 3, 1961 F. A. HAYES TWO-SPEED DRIVES FOR SEWING MACHINES 3 Sheets-Sheet 1 Filed Oct. 26, 1958 INVENTOR. FRANK A. HA YES ATTORNEY Jan. 3, 1961 F. A. HAYES -SPEED DRIVES FOR SEWING MACHINES TWO 3 Sheets-Sheet 2 Filed Oct. 20, 1958 INVENTOR. FRANK A. Hares 62w jimmy Jan. 3, 1961 F. AfHAYEs TWO-SPEED DRIVES FOR SEWING MACHINES 5 Sheets-Sheet 3 Filed Oct. 20, 1958 INVENTOR. FRANK A. HAYES ATTORNEY rates TWO-SPEED DRIVES F OR SEWING MACHINES Filed Oct. 20, 1958, Ser. No. 768,311

11 Claims. (Cl. 74-785) The present invention relates to a two-speed drive for sewing machines and particularly to a two-speed drive of tne planetary type.

The speed at which a sewing machine is operated must be varied in accordance with the operation being performed and with the skill of the operator. For straightaway sewing, and with a skilled operator, the machine is operated at maximum speed. However, with an operator of reduced skill and with a more complex sewing operation, the machine is operated at lower speeds. Since the average user of a family-type sewing machine is relatively unskilled, and since these machines are used for almost all sewing operations, it is advantageous to provide a two-speed drive for family-type sewing machines which will provide a convenient control for low speed operation as well as for high speed operation. Since the machine must be capable of being operated for bobbin winding, the drive also must be adapted for free running of the hand wheel.

At the same time, a two-speed drive which will limit the sewing machine to a low speed range of operation as well as to a high speed range of operation should not adversely affect the torque developed by the drive. Since the low speed range of operation is usually used for sewing operations involving attachments such as a ruffling attachment, or a zigzag work-jogging attachment, or a buttonhole attachment, an increased torque is required at relatively low speed.

A two-speed planetary type drive which has heretofore been proposed for family-type sewing machines, not only affords the desired control, i.e., a low speed range, a high speed range and free running for bobbin winding, but also the desired increased torque at low speed. However, there are numerous limitations which have heretofore made such a drive impractical for commercial use. Because of price limitations, the drive must be relatively economical, and also, since some purchasers would not be willing to pay the additional price for such a drive, it should be such that it involves a minimum of special parts and of alteration of the machine so that the machine may conveniently and economically be fitted selectively with a conventional drive or a two-speed drive. Another important feature of a planetary two-speed drive for family sewing machines is that it must be simple to operate to the point where it can be used by the most inexperienced operator and by operators of very little mechanical aptitude. Being a family-type sewing ma chine, the drive must also be relatively quiet in operation and must be dependable, durable and trouble-free.

With these limitations in mind, the primary object of this invention is to provide a two-speed planetary drive suitable for use with family-type sewing machines. More particularly, it is an object of this invention to provide a planetary drive unit which is relatively inexpensive, dependable, durable, trouble-free, quiet in operation, and adapted to be provided with a control mechanism that is simple to operate in order to provide for a low speed range of operation, a high speed range of operation and a bobbin winding operation.

ice

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

Fig. 1 is a fragmentary elevational view of a sewing machine fitted with a two-speed planetary drive unit in accordance with this invention and in which the drive is shown in vertical section.

Fig. 2 is an end elevational view of the planetary drive unit of Fig. l, and in which the end cover plate has been broken away.

Fig. 3 is a fragmentary vertical sectional view taken substantially on the line 3-3 of Fig. 1.

Fig. 4 is a vertical sectional view taken substantially on the line 3-3 of Fig. l, but in the opposite direction as indicated by the arrows 4-4.

Fig. 5 is a view similar to Fig. 1, but on an enlarged scale and showing the parts in a different position.

Fig. 6 is a detail sectional view taken substantially on the line 66 of Fig. 5.

With reference to the drawings, the present invention is illustrated as applied to a sewing machine having a frame including a vertically arranged standard 1 and a laterally extending bracket arm 2 mounted upon the upper end of the standard 1. The machine is fitted with a rotary main drive shaft 3 arranged longitudinally of the bracket arm and journaled at the standard end thereof in a bearing bushing 4. The two-speed drive is designed to be mounted upon the end of the shaft 3 which extends through the bushing 4 to the exterior of the frame.

The end of the main shaft 3 is provided with an extension comprising a double-stepped sleeve 5 that is secured on the shaft by a bolt 6. Journaled upon the sleeve 5 is a planet carrier 7 which, for manufacture and assembly purposes, is made in three parts, i.e., a sleeve 8 which forms the hub thereof and which is journaled on the sleeve 5, a flange 9 which is mounted on the sleeve 5 between the inner end of the sleeve 8 and the shoulder at the outer end of the bushing 4 and which is keyed to the sleeve 8 for rotation as indicated at It and an annular planet carrier element 11 which is mounted on the flange 9 by screws 12. Mounted on the planet carrier element at equally spaced points are three planets 13 in the forms of wheels which are journaled upon studs 14 press fitted in the planet carrier element 11, a bearing sleeve 15 being mounted on the studs and the wheels being held on the studs by snap rings 16. The wheels 13 are formed with metallic hubs 17, and the peripheries thereof are smooth and are covered with a friction-enhancing resilient material and preferably are provided with rubber tires 18.

A reaction element 19 is mounted upon the enlarged diameter end of the sleeve 5, for rotation relative thereto. The reaction element 19 comprises a flange portion 20 arranged normal to the shaft 3 and an overhanging hood portion 21 having a planet-engaging internal surface 22 at the outer edge which is concentric of the main shaft 3 and in cooperation with the wheel 13. To insure against relative motion between the periphery of the wheels 13 and the surface 22, the surface 22 is provided with ridges which are designed so that the periphery of the wheels 13 are slightly compressed when the unit is assembled or in other words, the wheels 13 and the surface 22 are in resilient engagement. Since the engagement between the surface 22 and the wheels13 is'not ,critical because of the resiliency'of the wheels, the shape 3 of the surface 22 is not critical and can therefore be designed so that the ridges can be formed by relatively inexpensive manufacturing processes. In the illustrated design, a simple undulating or sinuous configuration is rolled into the surface 22.

A driving element 23 is mounted on the sleeve 8 and comprises the hand wheel of the machine. For manufacture and assembly purposes, the driving element 23 is made in two parts consisting of a hub portion 24 and a belt pulley portion 25. The hub portion 24 has a sleeve 26 that is mounted on the sleeve 8 and a flange 27 which the pulley portion 25 is mounted by screws 28 and which also serves as a cover plate for the planetary unit. The sleeve 26 has a peripheral planet-engaging surface 29 concentrical relatively to the main shaft and in olling engagement with the wheels 13 and which, like the surface 22, is formed with ridges to insure against slipping. The pulley portion 25 of the driving element 23 is formed with a belt groove 30 in which a driving belt 31 is adapted to run.

A locking means is provided for selectively coupling the planet carrier 7 to the shaft 3. For this purpose, the outer end of the sleeve 5 is counterbored to receive a mounting block 32 having a central bore in which an adjusting shaft or countershaft 33 is mounted for turning relatively to the block 32. The countershaft 33 is held in the block 32 by a snap ring 34 and a cam element 3-5 press fitted on the countershaft 33. The cam 35 comprises an axial displacement cam having two op positely disposed peaks 36 and with two valleys 37 between the peaks. A hand knob 33 is mounted on the free end of the countershaft 33 and is keyed to the countershaft for unitary turning movement by a pin 39 eX- tendin through the countershaft 33 and, for assembly purposes, is seated in a groove, Fig. l, in the inner face of the hand knob 38 which is in turn secured on the countershaft 33 by a snap ring 46. The outer ends of the sleeves and 8 are castcllated or, in other words, are provided with registerable

radial grooves

41 and 42, respectively. A clutch disc 43 having radially extending arms 44 is loosely mounted on the countershaft 33 with the arms 44* adapted to be seated in the grooves ll and 42. The clutch disc 43 has a central aperture 45 that is large enough so the disc will move freely over the cam 35 and has a pair of oppositely arranged inwardly extending arms 46 that are adapted to engage the face of the cam 35. The arms 46 are small enough widthv ise so that they can seat on the valleys 37 of the cam and have grooves 47 in the face thereof for receiving the peaks 36 of the cam. A dished washer-type spring 48 is mounted on the countershaft 33 between the clutch disc and 1e inside of the hand knob 33 for biasing the disc axially of the shaft 3 and thus holding the arms 46 seated in the valleys 37 or on the peaks 36 of the cam. The spring 41-3 has a plurality of radially extending arms at the periphery thereof corresponding to the arms 44 of the clutch disc 43 that are adapted to be seated in the

grooves

41 and 42 of the

sleeves

5 and 8. To prevent possible misalignment of the arms 44 of the clutch disc and the corresponding arms of the spring 48, the sleeve 5 is made longer than the sleeve 8 so that the arms 44- rcmain in the grooves 41 in the sleeve 5 when the clutch disc 43 is forced outwardly against the action of the spring 4 3 by turning the hand knob 38 and thus turning the cam 35, as illustrated in Fig. 1.

The clutch disc 43 serves to couple the planet carrier 7 to the main shaft 3 for unitary rotation or to uncouple it for rotation relatively to the main shaft. When the hand knob 38 is turned, the countershaft 33 and the cam element 35 are turned with it. Upon a quarter turn of the hand knob 38 from the position illustrated in Fig. l to the position illustrated in Fig. 5, the inwardly extending arms 46 of the clutch disc 43 are moved oil the peaks 36 of the cam element 35 and the clutch disc 43 is moved inwardly by the spring 48 to move the radial arms 44 of the clutch disc 43 into the grooves 42 of the sleeve 8. A slight turning of the driving element 23 may be required to align the grooves 42 with the arms 44. The arms 44 thus extend through both the grooves 41 of the sleeve 5 and the grooves 42 of the sleeve 8, keying them together for unitary rotation. Upon a further quarter turn of the hand knob 38, the cam element 35 acts on the arms 48 to effect an outward displacement of the clutch disc 43 against the action of the spring 48 which moves the radial arms 44 out of the grooves 42 of the sleeve 8. The planet carrier 7 is thus uncoupled from the main shaft 3 for rotation relatively thereto.

For selectively securing the reaction element 19 to the driving element 23 for locking the two together for unitary rotation and to the frame of the machine for holding it stationary, there is provided a latch means comprising a control element 49 loosely surrounding the enlarged inner end of the sleeves for axial sliding movement and for rotation relatively thereto. The control element 49 has an outer flange 50 having four pairs of radially extending lugs 51 arranged equidistantly about the periphery thereof, which lugs 51 are adapted to be seated in grooves 52 in the rear face of the belt pulley portion 25 of the driving element 23. The control element 49 is mounted on the hub of the reaction element 19 and is biased outwardly or to the right in Figs. 1 and 5 to engage the lugs 51 in the grooves 52 by three studs 53 that are mounted in the flanged portion 20 of the reaction element for axial sliding movement and riveted to the flange 54) of the control element. Coil compression springs 54, Fig. 5, surround the studs 53 on the outside of the flanged portion 20 and react between the flanged portion 20 and snap rings 55 on the router ends of the studs totension the studs and thus pull the control element 45 outwardly. With the control element 49 secured to the reaction element 19 for rotation, moving it outwardly axially of the shaft 3 to engage the lugs 51 in the groove 52 which locks it to the driving element 23 acts to lock the reaction element to the driving element. Moving the control element 49 in the opposite direction frees the reaction element 19 for rotation relatively to the driving element For moving the control element 49 inwardly against the action of the springs 54 and thus retract the lugs 51 from the grooves 52 and simultaneously lock it against rotation, the control element 49 has an inner flange 56 comprising a plurality of equally spaced radially extending lugs 57 with gaps between them. A resilient sheet metal lever 58 is pivotally mounted intermediate its ends on lugs 59 on the belt cover 60 which is in turn secured to the frame of the machine. The upper end of the lever 58 is bifurcated to provide arms 61 that straddle the hub of the control element 49 between the flanges 5t) and 56. On the faces of the arms 61 that engage the flange 56, there are struck rises 62 which are adapted to enter the gaps between the lugs 57. For swinging the lever 58, the lower arm 63 thereof is adapted to be engaged by a selected one of two pairs of pins 6 3 and 65 mounted on a control shaft 66 that is journalcd in the belt cover 60 and, at the front of the machine at a point accessible to the operation, has an operator actuated control arm 67. The pins 64 are relatively short and comprise stops against which the arm 03 of the lever 53 abuts when the lever is in the high speed posi' tion as illustrated in Fig. l, i.e., the position in which the arms 61 lie between and out of engagement with the flanges 5t and 56 and the control element 49 is biased outwardly by the springs 54 to engage the lugs 51 in the grooves 52 and thus couple the control element and the reaction element 19 to the driving element. A coil tension spring 68 is connected at one end to the lever arm 63 and at the other end to a bracket 69 secured to the belt cover 60 to bias the lever 58 into the high speed position. The pins 65 are relatively long so that when the control shaft 66 is turned to the position illustrated in Fig. 5, the pins 65 force thelever arm 63 outwardly,

thus swinging the arms 61 inwardly and thereby sliding the control element 49 axially of the shaft 3 to retract the lugs 51 from the grooves 52. Movement of the control element 49 is limited by the studs 53. The lever 58 is resilient so that the ends of the arms 61 at the rises 62 can be moved a greater distance than the control element 49 moves, thereby flexing the lever and resiliently biasing the control element 49 to its stationary position. This bias also insures seating of the rises 62 in the gaps between the lugs 57 thereby coupling the lever 58 to the control element 49 for holding the control element stationary. Further, in the event that the control shaft 66 is actuated while the machine is being operated, the rises 62 can move in and out of successive gaps between the lugs 57 to bring the control element 49 gradually to a stop without damaging the elements. To assist in positioning the

pins

64 and 65, the lever arm 63 is formed with a depression 70 in which the ends of the pins are seated and also, a pair of stop pins 71 are provided on the belt cover 60 in position to be engaged by the control lever 67 alternatively when the

pins

64 and 65 are in operative position.

In operation, for normal direct drive, the lever arm 67 is shifted to the full line position in Fig. 1. The pins 64 are in engagement with the lever 58 and in effect, the control element 49 is released so that the springs 54 pull it toward the driving element 23. The lugs 51 of the control element thus enter the grooves 52 of the driving element 23 to couple the driving element 23 to the reaction element 19 for unitary rotation. The control knob 38 is turned to the position illustrated in Fig. 5 to force the clutch disc 43 inwardly with the arms 44 seated in the

grooves

41 and 42 of the

sleeves

5 and 8, thus coupling the planet carrier 7 to the main shaft 3 for unitary rotation. Rotation is impacted to the driving element 23 through the belt 31. Since the reaction element 19 and the driving element 23 are coupled together for unitary rotation, the planet, wheels 13, which are in engagement with both of them, cannot rotate but is carried around with them. This action rotates the planet carrier 7 which, through the sleeve 8, clutch disc 43, and sleeve 5, imparts rotation to the main shaft 3. The main shaft 3 thus is rotated at a one-to-one ratio relatively to the driving element 23.

Without adjusting the control knob 38, the control lever 67 is moved to the full line position as illustrated in Fig. 5 to obtain slow speed operation. When the lever 67 is moved, the pins 65 are brought into engagement with the lower end 63 of the lever 58 to pivot the lever 58 and thereby move the control element 49 away from the driving element 23 to retract the lugs 51 from the grooves 52. The driving element 23 is thus released for rotation relatively to the reaction element 19 and simultaneously, the reaction element 19 is held stationary by the seating of the rises 62 on the lever arms 61 in the gaps between the lugs 57 of the control element. Now, as the driving element 23 is rotated by the belt 31, its engagement with the planet rollers 13 at the surface 29 causes the planet wheels 13 to rotate. Since the planet wheels 13 are also in engagement with the inner surface 22 of the reaction element 19, which is now stationary, they cannot rotate freely but must roll around on the surface 22, thus advancing the planet carrier 7 and rotating the main shaft 3 at a reduced speed relatively to the rotation of the driving element 23. R0- tation of the planet carrier 7 is at a speed depending upon the difference in the circumferences of the

surfaces

29 and 22. In the illustrated embodiment rotation of the driving element 23 relatively to rotation of the planet carrier is at a ratio of approximately three and onequarter to one.

For bobbin winding, the control knob 38 is turned to force the clutch disc 43 outwardly to retract the arms 44 from the grooves 42 of the sleeve 8, thus freeing the main shaft 3 from the planet carrier 7. Since the only drive connection to the main shaft 3 is from the planet carrier 7, this adjustment provides for free running of the planetary unit on the sleeve 5 regardless of the position of the control lever 67.

In summary, adjustment of the hand knob 38 to the position illustrated in Fig. 5, establishes a driving relation between the driving element 23and the main shaft 3 which, depending upon the adjustment of the control arm 67, will be a direct drive or a reduced speed drive. In the full line position of Fig. 1, the arm 67 is set for direct drive and in the full line position of Fig. 5, the arm 67 is set for reduced speed drive. Adjustment of the hand knob 38 to the position illustrated in Fig. 1, regardless of the setting of the lever 67, releases the driving element for running freely and thus adapts it for bobbin winding.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus described the nature of the invention, what I claim herein is:

1. In a sewing machine having a frame, a main drive shaft journaled for rotation in said frame, and a planetary drive unit on said shaft comprising a planet carrier, a driving element, and a reaction element journaled for independent rotation on said shaft, said driving element and said reaction element having coaxial planet engaging surfaces, a plurality of planets carried by said planet carrier and disposed between said planet engaging surfaces, said planets having peripheral surfaces in engagement at diametrically spaced points with said planet engaging surfaces, means for selectively coupling said planet carrier to said shaft for unitary rotation and for rotation independently thereof, operator controlled means for selectively coupling said reaction element to said driving element for unitary rotation or to said frame for holding the same stationary, said peripheral surfaces of said planets being smooth and formed of rubber or rubber-like resilient friction-enhancing material, and said planets being dimensioned relatively to said planet engaging surfaces for deforming said resilient material slightly at the points of contact.

2. In a sewing machine having a frame, a main drive shaft journaled for rotation in said frame, and a planetary drive unit on said shaft comprising a planet carrier having a hub journaled for rotation on said shaft, a driving element having a hub journaled for rotation on the hub of said planet carrier, a reaction element journaled for rotation on said shaft, said driving element having a peripheral planet engaging surface on the hub thereof and said reaction element having an internal planet engaging surface arranged coaxially of and overhanging the planet engaging surface of said driving element, a plurality of planets carried by said planet carrier and disposed between said planet engaging surfaces, said planets having peripheral surfaces in engagement at diametrically spaced points with said planet engaging surfaces, means for selectively coup ing said planet carrier to said shaft for uni tary rotation and for rotation independently thereof, operator controlled means for selectively coupling said reaction element to said driving element for unitary rotation or to said frame for holding the same stationary, said peripheral surfaces of said planets being smooth and formed of rubber or'rubber-like resilient friction-enhancing material,'and said planets being dimensioned relatively to said planet engaging surfaces for deforming said resilient material slightly at the points of contact.

3. In a sewing machine having a frame, a main drive shaft journaled for rotation in said frame, and a plane- 't'ary unit on said shaft comprising a planet carrier, a driving element, and a reaction element journaled for independent rotation on said shaft, said driving element and said reaction element having coaxial planet engaging surfaces, a plurality of planets carried by said planet carrier and disposed between said planet engaging surfaces, said planets having peripheral surfaces in engagement at diametrically spaced points with said planet cngaging surfaces, means for selectively coupling said reaction element to said driving element for unitary rotation and to said frame for holding the same stationary, and means for selectively coupling said planet carrier to said shaft for unitary rotation therewith or for rotation independently thereof comprising a countershaft journaled coaxially of said shaft for angular adjustment relatively thereto, clutch means mounted for movement endwise of said shaft for keying said planet carrier to said shaft and for freeing the same for rotation relatively thereto, spring means biasing said clutch means into keying position, an axial displacement cam on said countershaf-t for effecting displacement of said clutch means endwise of said shaft out of keying position against the action of said spring means, and means for manually effecting angular adjustment of said countershaft.

4. In a sewing machine having a frame, a main drive shaft journaled for rotation in said frame, and 'a'planetary drive unit on said shaft comprising a planet carrier having a hub journaled for rotation on said shaft, a driving element journaed for rotation on the hub of said planet carrier, a reaction element journaled for rotation on said shaft, said driving element having a peripheral planet engaging surface on the hub thereof and said reaction element having an internal planet engaging surface arranged coaxially of and overhanging the planet engaging surface of said driving element, a plurality of planets carried by said planet carrier and disposed between said planet engaging surfaces, said planets having peripheral surfaces in engagement at diametrically spaced points with said planet engaging surfaces, means for selectively coupling said reaction element to said driving element for unitary rotation or to said frame for holding the same stationary, and means for selectively coupling said planet carrier to said shaft for unitary rotation therewith and for rotation independently thereof comprising a countershaft journaled coaxially of said shaft for anguar adjustment relatively thereto, a clutch disc surrounding said countershaft andmounted for movement endwise of said shaft and having a plurality of radially extending arms on the periphery thereof, said shaft and the hub of said planet carrier having radially extending grooves adapted to receive said arms for keying said planet carrier to said shaft, spring means for biasing said clutch disc endwise of said shaft for seating said arms in said grooves, an axially displacement cam on said countershaft for effecting displacement of said clutch disc against the action of said spring means to remove the arms from keying engagement with said grooves, and means for manually effecting angular adjustment of said countershaft.

5. A sewing machine in accordance with claim 4 in which a sleeve is mounted on the free end of said shaft and constituting an extension of said shaft, and said planetary unit is mounted upon said sleeve with said countershaft mounted in said sleeve and said radially extending grooves are formed in said sleeve and in the hub of said planet carrier.

6. In a sewing machine having a frame, a main drive shaft journaled for rotation in said frame, and a planetary unit on said shaft comprising a planet carrier, a driving element and a reaction element journaled for independent rotation on said shaft, said driving element and said reaction element having coaxial planet engaging surfaces, a plurality of planets carried by sa'd pIanet carrier and disposed between said planet engaging surfaces, said planets having peripheral surfaces in engagement at diametrically spaced points with said planet engaging surfaces, means for selectively coupling said planet carrier to said shaft for unitary rotation therewith and for rotation independently thereof, and operator controlled means for selectively coupling said reaction element to said driving element for unitary rotation or to said frame for holding the same stationary comprising a control element mounted on said reaction element for unitary rotation therewith and for movement axially relatively thereto, means for securing said control element to said driving element for unitary rotation therewith upon axial movement of said control element in one direction, means for securing said control element to the frame for preventing rotation thereof relatively to said frame upon axial movement in the other direction, and manually controlled means for effecting axial movement of said control element.

7. A sewing machine in accordance with claim 6 in which said means for selectively securing said control element to said driving element comprises a plurality of radially extending arms on said control eiement and a plurality of radially extending grooves on said driving element adapted to receive said arms upon axial movement of said control element.

8. A sewing machine in accordance with claim 6 in which said means for selectively securing said control element to said frame comprises a plurality of radially extending arms on said control element and means mounted on said frame for cooperating with said arms to prevent rotation of said control element.

9. A sewing machine in accordance with claim 6 in which said means for effecting axial movement of said control element comprises spring means for biasing said control element in one direction and operator influenced lever for moving said control element in the other direction against the action of said spring.

10. A sewing machine in accordance with cla m 6 in which said control element includes a pair of axially spaced radially extending flanges, and in wh'ch said means for securing said control element to said drIving element and to said frame comprises a pzurality of radially extending arms upon each of said flanges, said driving element having a plurality of rad ally extending grooves for receiving the arms on one of said flanges, and means mounted on said frame for cooperating with the arms on the other of said flanges to prevent rotation of said control element.

11. A sewing machine in accordance with claim 10 in which said means for effecting axial dfsplacement of said control element comprises spring means for biasing said control element in one direction, and a lever pivotally mounted on said frame and including a first lever arm having a bifurcated end disposed between the flanges of said control element, and a second lever arm, a control shaft having a laterally extending element adapted to engage said second lever arm upon turning of said shaft for moving said control element against the action of said spring, and operator controlled means for turning said control shaft.

References Cited in the file of this patent UNITED STATES PATENTS 2,410,921 Avila Nov. 12, 1946 2,425,188 Honigman Aug. 5, 1947 2,464,498 Gilliam Mar. 15, 1949 2,834,229 Graybill May 13, 1958 OTHER REFERENCES Ser. No. 378,638, Brissonet-et a1. (A.-P.C.), published May 4, 1953.