US2338611A - Start-and-stop mechanism for sewing machines - Google Patents

Description

Jan. 4, 1944. woop smndr-Aun swor MECHANISM FOR SEWING MACHINES Filed March 12, 194:2 6 Sheets-Sheet 1 A. R. vgpon Jan. 4, l 944.

START-AND-STOP MECHAN ISM FOR SEWING MACHINES Filed March 12, 1942 6 Sheets-Sheet 2 wumew 3 M A H mm A. R. WOOD START AND-STOP MECHANISM FOR SEWING MACHINES Jan. 4, 1944.

6 Sheets-Sheet 5 Filed March 12, 1942 Jan. 4,1944. Y A; R. WOOD 2,3

START-AND-STOP MECHANISM FC JR SEWING MACHINES Filed March 12, 1942 6 Sheets-Sheet 4 mmm- 3% v Z J Jan. 4, 1944. R WOOD 2,338,611

START-AND-STOP MECBANIS M FOR SEWING MACHINES- Filed March 12, 1942 6 Sheets-Sheet 5 41 23 m I 7 3/ I Jan. 4, 1944. 3 O D 2,338,611

START-AND-S'IOP MECHANISM FOR SEWING MACHINES Filed March 12. 1942 6 Sheets-Sheet 6 .95 9i 105 90 w 6 09 ln \I Z 93' 10F 211 ,94

90 1 1 H .12" "191 g: .r--- l, a F Q I Patented Jan. 4, 1944 START-AND- STOP MECHANISM FOR SEWING MACHINES Alfred R. Wood, Bridgeport, Conn, assignor to The Singer Manufacturing Company, Eliza-- beth, N. J., a corporation of New Jersey Application March 12, 1942, Serial No. 434,334

18 Claims. (01. 112-67) This invention relates to sewing machines, more particularly of the automatic type embodying stitch-forming mechanism and a work-clamp, with means for relatively moving them to sew a group of stitches, and with a stop motion for arresting the action of the machine at the completion of the stitching cycle. Such a machine is disclosed in the U. S. patent to E. B. Allen, No. 784,291, issued March 7, 1905.

Machines of the type disclosed in the Allen patent heretofore have been operated successfully at a speed of about 2000 stitches per minute. The stop-motion with which the machine was equipped was quite satisfactory in its operation, and particularly so when constructed in accordance with the teachings of the U. S. patent to Allen et al., No. 1,878,091, issued September 20, 1932. Attempts have been made to operate the machines at speeds in excess of 2000 stitches per minute. These efforts have not been very successful for the reasons that the acceleration of the machine from zero to full speed is slow and time-consuming, and that in view of the increased energy to be absorbed by the stop-motion device, the blow imparted to the usual stopcam buffer-spring is too great and results in breakage and distortion or undue Wear on the parts. Further, in increasing the speed of operation of the prior machines from 2000 to 3000 stitches per minute, larger belt pulleys had to be applied to the driving shafts or power transmitters from which the sewing machines were driven, and these larger pulleys frequently could not be readily accommodated on the existing supporting table-structures or power tables because of the scarcity of sufiicient room to receive the required larger pulleys. Obviously larger pulley diameter means increased linear speed of the driving belt, which increased linear speed has the effect of decreasing the life of the belt.

The present invention has for its primary object to provide a start-and-stop mechanism, which will permit of higher machine speeds with increased production, and in which the acceler ation is rapid, the shock of stopping the machine is materially reduced and buffer-spring breakage substantially no appreciable shock or impact and yet in. a manner to afford a definite final stop position of the main-shaft.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated inthe accompanying drawings, of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art. a

In the accompanying drawings,

Fig. l is a left side elevational view of a buttonhole machine embodying the invention.

Fig. 2is a rear end elevational view of the machine.

Fig. 3 is a bottom plan view of the machine. Fig. 4 is a top plan view, partly in section, showing the details of the pulley assemblyon the countershaft and the gearingconnectingthe countershaft with the. main-shaft of the sewingv machine. Fig. 5 represents anenlarged vertical sectional view taken substantially along the line 5-5, Fig. 4, with. the cover-plate removed to exposethe stop-cam buffer-spring. Fig. v6 represents an elevational view of the pulley and stop-cam assembly illustrated in Fig- 5, with a portion of the assembly sectioned along alinerepresented as 66,Figl.5. Fig. '7 represents a vertical sectional view taken. along the line l.l,Fig. 6. Fig. 8 is a fragmentary left side elevational view, with the machine-bed. in section, showing the driving belt on the slow speed pulley and the position of the belt-shipper andits related. mechanism during slow speed operation of. the machine at the beginningof the stitching cycle Fig. 9 represents a vertical sectional view taken substantially along the line 99,.Fig., 8. Fig. 10 is a view similar to Fig 8 illustrating. the position of the belt-shippershifting mechanism just at the completion of its action in shifting the driving .belt from the low speed pub; ley to the high speed pulley. 1

Fig. 11 represents a vertical sectional view. taken substantially alongt-he line 1 II l, Fig. 10., Fig. 12 is a fragmentary left side elevational view of the belt-shipper shifting mechanism-, showing in full lines, the barrel-cam follower-pin latched in retracted position and, in dotted lines,

the.subseduent.stitchingcyclair Fig. 13 is a right hand end view of the mechanism shown in Fig. 12.

Fig. 14 represents a fragmentary horizontal sectional view taken substantially along the axis of the barrel-cam follower-pin.

Fig. 15 represents an enlarged top plan view, partly in section, illustratin the cam controlled release for the latch which is adapted to hold the belt-shipper in position to maintain the driving belt upon the high speed pulley; the parts being shown in latch-releasing position.

Fig. 16 represents a vertical sectional view taken substantially along the line [6-46, Fig. 1.

Fig. 17 is a fragmentary left side elevational view, showing, in full lines, the barrel-cam follower-pin latch being released by the buttonhole cutter actuating mechanism at the end of the stitching cycle and, in dotted lines, the position of the buttonhole cutter actuating mechanism and the follower-pin latch releasing lever when the machine is in final stop position.

Fig. 18 represents a vertical sectional view taken substantially along the line I8|8, Fig. 17, showing the position of the stop-plunger which is journaled in the swinging stop-motion bracket when the parts are in the position illustrated in full lines in Fig. 17.

Fig. 19 represents an enlarged sectional view taken substantially along the line Ill-l9, Fig. 17.

In the preferred embodiment of the invention illustrated, the machine is constructed with a frame including a bed I from one end of which rises a standard 2 of an overhanging bracket-arm 3 terminating in a head 4. Journaled in the bracket-arm 3 is a main-shaft 5 connected within the head 4 to the usual endwise reciprocatory and laterally vibratory needle-bar 15 carrying a needle I. Complemental to the needle in the formation of lock-stitches is a conventional loop-taker 8 driven by the bed-shaft 9 operatively connected to the main-shaft 5 in a manner represented in U. S. Patent No. 784,291, issued to E. B. Allen, March '7, 1905.

As is customary in machines of the type selected to illustrate the present invention, the work to be sewn is retained in a work-clamp represented by the reference numeral 0. By means of the work-clamp the work is slowly moved stepby-step fashion under the endwise reciprocatory and laterally vibratory needle I, first away from the standard 2 and then towards the standard to cause the first and second rows of side zigzag stitches to be laid side by side in the work. At the ends of the rows of side stitches the usual groups of barring stitches may be formed, provided the machine is fitted with a barring device. The work-clamp l derives its step-by-step movements from a feed-cam I l secured upon the lower end of a feed-shaft I2; the connections between the work-clamp and feed-cam being constructed substantially in accordance with the disclosure in the U. S. Patent No. 785,061, issued to E. B. Allen, on March 14, 1905.

The feed-shaft I2 is operatively connected to the main-shaft through mechanism designed to impart intermittent rotary movement to the feedshaft, said mechanism comprising a pitman I 3 (Fig. 2) connected at its upper end to an eccentric (not shown) mounted on the main-shaft 5 and at its lower end to the horizontal arm l4 of a tubular rock-shaft I5 journaled upon a pivotstud l6 fixed in the lugs l1, I1 depending from the bed I. Depending from the tubular rockshaft and preferably formed integrally therewith is an arm l8 embraced by one end of a link 19 of which the other end is suitably connected to a slotted arcuate arm 25. The arcuate arm 20 at its inner end is fastened to an internal spider 2| of a common form of intermittent clutch provided on the bottom face of the feedcam II. By means of the mechanism just described the feed-cam H and the feed-shsaft 12 are intermittently rotated in timed relation with the stitch-forming mechanism to properly shift the work-clamp and produce the desired buttonhole or tack determined by the cam grooves cut in the feed-cam l 1.

Driving power is applied to the machine through a single belt 22 adapted to run upon one of three nested pulleys, a loose pulley 23, a low speed pulley 24 and a high speed pulley 25, all of which are supported upon a countershaft 26 journaled in bearing lugs 21, 21 provided on the bracket-arm 2. As shown in Fig. 4, the loose pulley 23 freely rotates through the ball bearing 28 upon the extended hub 29 of the low speed pulley 24. The low speed pulley 24 is journaled to rotate freely upon the countershaft 26. Mounted upon the free end of the extended hub 29 of the low speed pulley 24 is a spur-gear 30 of which the hub-face is notched, as at 3|, Figs. 7 and 8, to receive a key-disk 32 by which the spurgear 30 is fixed to rotate with the low speed pulley 24. The key-disk 32 is secured in looking position within the notch 3| by a nut 33 threaded upon the hub 29. A cap-screw 34 serves to hold the pulley assembly upon the countershaft 26.

Meshing with the spur-gear 30 is a second spur-' gear 35 fast upon the main-shaft 5; the ratio between spur-gears 3E) and 35 preferably being oneto-one. Through the mechanism above described it will be understood that when the belt 22 drives the low speed pulley 24 the latter, through the spur-gears 3D and 35, rotates the main-shaft 5 at a speed equal to that of the low speed pulley, which in the present case is equal to the speed of the belt 22. p

The high speed pulley 25, as shown in Figs. 4 and 6, is preferably formed as a ring having a snug fit on the periphery of a spur-gear 36 which is secured by means of a taper-pin 3? upon the countershaft 25. Meshing with the spur-gear 36 is a pinion 38 pinned, as at 39, to the mainshaft 5; the speed ratio between the spur-gear 36 and the pinion 38 preferably being two-toone. When the driving belt 22 is running on the high speed pulley 25, the main-shaft 5 is driven through the speed-multiplying gearing 3'5 and 38 at a speed equal to twice the speed of the driving pulley 25. It will be obvious from the above description that when the driving belt 22 is on the low speed pulley 24 the main-shaft 5 is driven through the spur- gears 30, 35 at a speed equal to that of the low speed pulley, and that when the driving belt 22 is on the high speed pulley 25 the main-shaft is driven through the spur gear 36 and pinion 38 at a speed twice that of the high speed pulley 25. While the speed ratios as indicated above are preferable, it will be appreciated that they may be varied in accordance with the conditions required. It will be understood that each of the pulleys 23, 24 and 25 is provided with its own complete belt-groove and that in view of this fact good driving relationship exists between the respective belt-pulleys and the driving belt 22.

To provide means for stop-ping the machine at a predetermined final position, the machine illustrated'is equipped with a stop slightly yieldable to provide a cushioned abutment adapted to absorb the shock of stopping the moving parts of the machine. To this end, the spur-gear 36 has a forwardly extending hub 49 on which is journaled the usual stop-cam 41 having eccentric stop-plunger depressing portions 42 followed by stop and rebound-preventing notches 43. Preferably formed integral with the stop-cam H is a rearward extension 44, Figs. and 6, providing a movable block projecting through a clearance slot 44' into a circular cavity 45 formed in the spur-gear 36. Bearing against one face of the movable block 44 and disposed within the cavity 55 is a'buffer-spring 46 of which the other end bears against a fixed abutment-block 41 fastened to the spur-gear 38 by means of a securing screw 58 threaded into the spur-gear. In addition to holding the abutment-block 41 fast to spur-gear 36, the head-end of the securing screw 43 is disposed in a notch provided in the high speed beltpulley (Fig. 4) and prevents the pulley from turning relative to the spur-gear 36. A coverplate 48 closes the cavity and is held thereon by screws 55.

Mounted on the standard 2, at the base of the latter, is a bracket 5| having spaced arms 52 for the trunnion-screws 53 which support a tilting stop-motion lever 54. Mounted to slide vertically in the stop-motion lever 54 is the usual stopplunger 55 which is pressed upwardly by a spring 55. When the stop-motion lever 54 is in run-- ning position, as shown in Figs. 8 and 10, the upper end of the plunger 55 is disposed forwardly of the stop-cam 4i and is out of range of the latter. When the stop-motion lever 54 assumes its stopping position, as shown in Figs. 1 and 17, the plunger 55 is moved to a position under or within range of the cam 4!, whereupon the eccentric portion 42 of such cam first depresses the stop-motion plunger 55 against the force of the spring 55 and then releases the plunger as the latter rides off the end of the cocentric portion 42 and is projected upwardly into the stop-notch 43; the shock incident to the stopping of the moving parts being absorbed by the buffer-spring 55 acting between the movable block 44 and the fixed abutment-block.

The stop-motion lever 54 is held in its running position (Figs. 8 and 10) by means of a spring biased latch-lever 5'! which enters a notch 58 in the side of a treadle-controlled rod 59 endwise slidable through the machine-bed l; the rod 59 being connected at its upper end to the free end of an actuating lever 6!! rigid with the stop-motion lever 54. The latch-lever 51 carries an adjustable tripping-point (il which is acted upon at the end of the sewing cycle by the tripping-point 52 carried by the feed-wheel ll (Fig. 3); releasing of the latch-lever 5'! by the tripping-point 52 permitting a coil-spring 63 surrounding the treadle-controlled rod 59 to swing the stop-motion lever 54 with its plunger 55 toward and into the range of the stop-cam 4i. 7

As is customary in machines of the type chosen to illustrate the present invention, the buttonhole cutter blade 64 is operated to cut the buttonhole at the end of the stitching cycle by mechanism actuated by the stop-plunger 55 in a. manner fully disclosed in the U. S. Patent to E. 13. Allen, No. 743,213, November 3, 1903. Briefly, this mechanism comprises a horizontal arm 65 secured to the stop-plunger 55 by means of a screw 66 (Fig. 2) and carrying at its outer end a roller 61 entering a slot 68 (Figs. 1 and 1'7) in the rearward end of a lever 69 fulcrumed at H! on the standard 2. The lever 69 is connected in the usual manner to the cutter-carrying bar journaled in the machine-head 4 by means of a link H, lever 12 and link 13. It will be understood that through the connections just described the buttonhole cutter is given its downward, or worlesevering stroke, by the eccentric stopplunger depressing portion 42 of the stop-cam 4| when the stop-plunger 55 swings into the range of the stop-cam after release of the treadle-controlled rod 59 by the latch-lever 5?.

Concerning the mechanism for shifting the driving belt 22 from one to the other of the pulleys 23, 24 and 25, means are provided whereby, in starting the machine, the driving belt is manually shifted from the loose pulley 23 onto the low speed pulley 24 after which the belt is automatically shifted onto the high speed pulley 25 where it remains for a major portion of the stitching cycle. At approaching the end of the stitching cycle, the belt is automatically shifted from the high speed pulley 25 onto the low speed pulley 24 where it runs for a short period of time to effect a slowing up of the machine, after which the belt is automatically shifted onto the loose pulley 23 just preceding the throwing in of the stop-motion mechanism. Referring principally to Figs. 1, 8, 10 and 18, one of the trunnion-screws 53 which aids in supporting the stop-motion lever 54 is extended at its outer end and has mounted thereon a flanged sleeve I4 on which is freely pivoted a belt-shipper lever 15 secured upon the sleeve 14 by a cap-screw 16. Fixed to the upper end of the belt-shipper lever 15 by screws ll (Figs. 1 and 2) is a socketmember 18 apertured to adjustably receive a rod 19 carrying at one end a belt-embracing iork 80. The socket-member 18 has threaded into it a set-screw 8| adapted for holding the fork 8B in its adjusted position. Secured to the lower end of the belt-shipper lever I5 is an anglebracket 82 to which is attached one end of a coil-spring 83 connected at its other end to the machine-bed l. The coil-spring 83 serves to yieldingly urge the belt-shipper lever 15 in a direction to shift the driving belt 22 toward the loose pulley 23.

To provide for shifting the belt-shipper lever in a direction to move the belt 22 from the position shown in Fig. 1 to the position shown in Fig. 8, the belt-shipper lever 15 is provided with a control-arm 84 having a free end disposed to underlie a latch 85 pivoted at its lower end to F an arm 86 adjustably secured upon the upper end-portion of the treadle-controlled rod 58. The latch 85 is normally biased toward the control-arm 8 by a spring 81. By means of the latch 85 and the control-arm 85, it will be understood that when the treadle-controlled rod 59 is pulled down, the stop-motion lever 54 is swung about the trunnion-screws 53, thereby disengaging the stop-plunger 55 from the stopcam 41, and when the lost-motion between the control-arm 84 and the latch 85 (see Fig. 1) is taken up the latch 85 engages the control-arm 84 and swings the belt-shipper lever l5,the furl: and the driving belt 22 into a position shown in Fig. 8, which is the low speed position. When the belt runs on the low speed pulley 24. the latter drives the main-shaft 5 through the spur- gears 30 and 35 at a speed equal to that of the low speed pulley.

After the machine is started, the main-shaft 5turns through a predetermined number of revolutions at low speed after which the belt 22 is automatically shifted onto the high speed pulley 25, see Fig. 10. The means for automatically shifting the belt 22 from the low speed pulley onto the high speed pulley comprises a threepiece bell-crank lever having a horizontal arm 93 fulcrumed upon the fixed stud Iii (Fig. 19), a sleeve member 89 likewise fulcrumed upon the stud 19 and to which the horizontal arm 83 is attached by a screw 99, and a vertical arm 9! clamped at its lower end on the sieeve-mernber 89. The upper end of the vertical arm Si is formed with a boss 92 apertured to receive a cam follower-pin 93 whose inner end is adapted to enter a groove 94 in the one revolution switch-cam of cam-cylinder 95 secured upon the countershaft 2 5. The aperture in the boss 92 is enlarged to receive an expansionspring 96 (Fig. 14) which surrounds the pin 93 and at one end bears against a collar as on the pin to force the latter yieldingly into the camgroove 94. The follower-pin 93 is adapted to be detained in retracted position, or out of engagement with the cam-cylinder 3'5, by means of a latch-arm 9B freely pivoted at its lower end upon the stud It (Fig. 19); the upper extremity 01.the latch-arm being adapted to enter beneath the head 99 of the follower-pin as shown in Fig. 14. The follower-pin 93 is released and permitted to enter the cam-groove at through the action of a two-arm lever Iill (Fig. 17), fulcrumed on a stud Hi5 threaded into a bracket I02 attached to the standard One arm of the two-arm lever ltfi is adapted to be engaged by the lever t9, when the latter is turned about its supporting stud 19 to effect the customary work-severing stroke of the buttonhole cutter at the conclusion of the buttonholeproducing cycle, and pivoted about the stud it'll from the dotted line position into the full position, Fig. 17. This movement of the lever I90 forces the lever-arm 98, in opposition to the coil-spring I03, from beneath the follower-pin head 99 and permits the expansion spring 96 to bias the follower-pin 93 into cooperative relation with the cam-cylinder 95.

As clearly shown in Figs. 13, 14 and 1'7, the cam-cylinder 95 is out with spaced beginning and ending dwell-producing portions I 94 and I05, respectively, and an inclined portion I06 connecting the two dwell-producing portions. At the beginning of the dwell-producing portion I04 the cam-cylinder 95 is formed with a follower-pin let-in incline I #31, and at the end of the dwellproducing portion I 85 the cam-cylinder is formed with a follower-pin ejecting incline I08 which terminates in a slightly raised surface I09 (Fig. 17) adapted to complete the ejecting of the follower-pin 93, thereby permitting the latchlever 98 to snap beneath the head 99 of the follower-pin 93 and hold it in retracted position with its inner end spaced slightly from the periphery of the cam-cylinder 95. Provided on the periphery of the cam-cylinder and paralleling the ending dwell-producing portion I05 is a flange I I9 which serves to prevent the bell- crank lever 88, 9! from swinging back prematurely under the influence of a spring III against the cushioned stop-bracket IIZ secured by screws I I3 on the bracket-arm 3 (Fig. 1).

The mechanism for automatically shifting the belt 22 from the low speed pulley 24 onto the high speed pulley 25 operates in the following manner. When the belt 22 is shifted from the loose pulley 23 onto the low speed pulley 24, the

main-shaft 5 is rotated by the low speed pulley through the gears 30 and 35. As the main-shaft 5 rotates the pinion 38 fixed thereon drives the countershaft 26 through the gear 36 at one half the speed of the main-shaft. As the countershaft is rotated through approximately one-revolution the cam-cylinder by means of the groove 94 and follower-pin 93 imparts to the bell-crank lever 88, 9I a single rocking impulse in a counterclockwise direction, Fig. 8. This rocking impulse of the bell-crank lever moves the horizontal arm 88 of the bell-crank lever down into engagement with the control-arm 84 of the belt-shipper lever 15, following which the belt-shipper lever is moved in a clockwise direction to shift the driving belt 22 onto the high speed pulley 25, as shown in Fig. 10. After shifting the belt onto the high speed pulley, the belt-shipper lever I5 is held in proper position to prevent accidental dislodgement of the belt from the high speed pulley by a latch I I4 pivoted upon stud I I5 threaded into the bracket 5!. The latch H4 is urged by the spring H5 into cooperative relationship with the control-arm 84. After the latch I I4 effectively locks the belt-shipper lever 15 in the position shown in Fig. 10, continued rotation of the countershaft 26, now directly connected to the belt 22 by the pulley 25, rotates the cam-cylinder 95 and effects an ejection of the follower-pin 93 as the latter is engaged by the ejection incline I08 (Fig. 13). When the follower-pin 94 is completely ejected, the latch-lever 98 snaps beneath the head 99 on the follower-pin and holds the latter in retracted position. When the follower-pin 93 is completely retracted the bell-crank lever 88, 9i and the latch-arm 98 are swung by the spring III in a clockwise direction from the full line position to the dotted line position, Fig. 12, after the end of the flange I in has been advanced beyond the follower-pin 93, thus raising the horizontal arm 88 of the bell-crank lever out of engagement with the belt-shipper control-arm 84. The belt-shipper controls remain in this position during the remainder of the high speed portion of the stitching cycle. It will be understood that in starting the stitching cycle it has been found necessary to maintain the driving belt on the low speed pulley for only a relatively short time. In the machine illustrated, the cam-cylinder 95 has been cut sothat during the normal operation of the machine the belt 22 remains on the low speed pulley 24 for only approximately 1%; revolutions of the main-shaft.

At the end of the high speed portion of the stitching cycle, the belt 22 is shifted from the high speed pulley 25 back onto the low speed pulley 24. The means for accomplishing this is best shown in Figs. 1, 4 and 15. The feed-shaft I2 is intermittently rotated from the mainshaft 5 by means of connections including the clutch 2|. Secured upon the feed-shaft I2 is a flanged collar I i! formed with a tripping-point H3 adapted to engage one end of a latch-release lever H9 fulcrumed intermediate its ends on a depending support I 20 fixed at its upper end to the bracket I02 mounted on the standard 2. The other end of the lever H9 is adapted to engage the latch II4 and turn the same about its supporting stud H5 in opposition to the spring H9, thereby to release the belt-shipper controlarm 84 (Fig. 16) following which the belt-shipper arm 15, under the influence of the coil-spring 83, shifts the belt 22 onto the low speed pulley 24, see Fig. 8. It will be understood that when the driving belt is running on the high speed pulley 25, the low speed pulley 2-4 through the gearing 30, 35, 36 and 38 is rotated idly at twice the speed of the high speed pulley. This being true, it will be appreciated that as the driving belt 22 is shifted from the high speed pulley 25 onto the low speed pulley 24 there is, in efiect, abraking action between the belt 22 and the low speed pulley 24 which functions to brake the machine rapidly to a slow speed.

After the driving belt 22 has been shifted from the high speed pulley onto the low speed pulley, the machine operates at slow speed until such time as the tripping-point 62 on the feed-cam H engages the latch-lever 51 and swings the same out of the notch 58 in the treadle-controlled rod 59. Release of the rod 59 will permit the beltshipper lever 15 to shift the driving belt onto the loose pulley 23, and the stop-motion lever 54 to spring to its vertical position (Fig. 1'7), in which position the upper end of the stop-plunger 55 will be engaged by one of the eccentric portions 42 of the stop-cam and be depressed, after which the stop-plunger will be projected upwardly by its spring 55 into the succeeding stop-notch 43 and arrest further movement of the machine. Danger of the machine stopping before the stopnotch 43 registers with the stop-plunger 55 is eliminated in the present case by so adjusting the tripping-point 6! on the latch-lever 51 that the driving belt remains on the low speed pulley 24 up to all but the last half of the last revolution of the main-shaft completion of the last revolution being effected by the inertia of the moving parts of the machine. When the stopmotion lever springs to its vertical position and the stop-plunger 55 is being depressed by, the stop-cam 4!, the buttonhole cutting mechanism is actuated to cut the buttonhole slit through connections with the stop-plunger 55, as previously described. It will be observed in Fig. 17 that when the buttonhole cutter mechanism is actuated, the lever 69 operates the two-arm lever I09 to force the end of the latch-lever 98 from beneath the head 99 of the follower-pin 93, permittin-g the expansion spring 95 to bias the follower-pin toward the cam-cylinder 95 into proper position for the repetition of its intended function in the subsequent stitching cycle. Due to the slight lag in the shifting of the driving belt from the low speed pulley onto the loose pulley when the machine is operating under power, at the time the stop-motion cam initially acts to operate the buttonhole cutting mechanism, the driving belt 22 is half on the low speed pulley and half on the loose pulley, with the result that the buttonhole cutting mechanism is initially actuated under power, the completing of its operation being efi'ected by the kinetic energy stored up in the moving parts of the ma chine.

If it is desired to stop the machine before the completion of the stitching cycle, it is only necessary to release the latch-lever 51, thus permittingthe treadle-controlled rod 59, under the influence of the coil-spring 63, to spring upwardly,

thereby swinging the stop-motion lever 54 into its vertical position. To permit the belt-shipper lever to swing, under the influence of the coilspring 83, simultaneously with the stop-motion lever 54, the arm 85 on the rod 59 is provided at its free end with a latch-tripping-pin |2| adapted to move into contact with a cam I22 provided on the latch H4 and thereby pivot the latch H4 speed pulley across the low speed pulley and onto the loose pulley without interruption, for it will be understood that the initial rise of the treadlecontrolled rod 59, through the latch-trippingpin I2I, will release the latch H4 and the swinging of the belt-shipper lever under the action of the spring 83 will not be interrupted by the latch 85 for the reason that the latch 85 is connected directly to the treadle-controlled rod 59 and moves vertically out of effective range with the, rod 59.

If it is desired the machine can be made to travel through the complete stitching cycle at slow speed. This is accomplished by merely manually retracting the follower-pin 93, before the stitching cycle is begun, sufiiciently far as to permit the latch-lever 98 to snap beneath the head 99 on the follower-pin 93. This maintains the follower-pin 93 in retracted position throughout the entire stitching cycle, thus rendering the cam-cylinder 95 and its associated mechanism inoperable to effect a shifting of the driving belt from the low speedpulley onto the high speed pulley. If the machine is operating at low speed and it is desired to shift into high speed, it is merely necessary to manually swing the beltshipper lever 15 to shift the belt 22 from the low speed pulley onto the high speed pulley, in which position the. belt-shipper lever is held by'the latch H4. If the machine is operating at high speed and it is desired to operate the machine at low speed before the position for automatic shifting of the belt is arrived at, it is merely necessary to manually release the latch ll4.

It will be understood that the position for automatic shifting of the belt from the high speed pulley onto the low speed pulley may be varied in accordance with conditions desired by merely adjusting the collar H1 about the feedshaft [2. It has been found desirable to set the tripping point H8 in such a position that when stitching the shortest buttonhole to which the machine may be adjusted, the shifting from high speed into low speed occurs approximately three stitches before the end of the stitching cycle, If set in this manner, the conditionfor long buttonholes is automatically provided for. When stitching long buttonholes, the shifting of the belt occurs approximately eight stitches before the end of the stitching cycle.

Throughout the above description belt-pulley 24 is referred to as the low speed pulley and beltpulley 25 is referred to as the high speed pulley. It is to be understood that this nomenclature is employed merely for convenience and clarity and is not to imply that belt-pulley 24, when it is driving the machine, rotates less rapidly than does belt-pulley 25, when it is driving the machine. The difierent speeds of the main-shaft are obtained through the use of the two sets of gears 30, 35 and 36, 38. As illustrated, the gears 35, 38 have a speed-multiplying ratio, while the gears 30, 35 are of equal'size. Obviously, the gears 36, 38 could be made equal in size and the gears 30, 35 could have a speed-reducing ratio, without afiecting the two-speed operation of the machine It is preferable, however, to employ gears sized as illustrated and described for the reason that the two-speed operation of the maabout its Supput 5 to m releasg bfyt'h e 75 chine is obtained by drivingthe belt 22 at a mlni mum linear speed, thus increasing the life of the belt.

The invention is not to be understood as limited to the exact construction shown and described as it is obviously susceptible of material modification both in the form and arrangements of its parts without departure from the invention.

Having thus set forth the nature of the invention What I claim herein is;

1. A group-stitch sewing machine having, in combination, a main-shaft, a nested pulley assembly including a loose pulley, a low speed pulley and a high speed pulley, means operatively connecting said low speed pulley to said mainshaft, means operatively connecting said high speed pulley to said main-shaft, a single driving belt adapted to run upon each of said nested pulleys, a belt-shipper adapted to engage and shift said driving belt from one to the other of said nested pulleys, and means automatically controlled for moving said belt-shipper to shift said driving belt from said low speed pulley onto said high speed pulley and subsequently from said high speed pulley onto said low speed pulley and thence onto said loose pulley during each complete group-stitch cycle.

2. A group-stitch sewing machine having, in combination, a frame, a main-shaft journaled for rotation in said frame, a second shaft sustained by said frame, a nested pulley assembly mounted on said second shaft and including a loose pulley, a low speed pulley and a high speed pulley, means operatively connecting said low speed pulley tosaid main-shaft, means operatively connecting said high speed pulley to said main-shaft, a single driving belt adapted to run upon each of said nested pulleys, a belt-shipper adapted to engage and shift said driving belt from one to the other of said nested pulleys, and means automatically controlled for moving said belt-shipper to shift said driving belt from said low speed pulley onto said high speed pulley and subsequently from said high speed pulley onto said low speed pulley and thence onto said loose pulley during each complete group-stitch cycle.

3. A group-stitch sewing machine having, in combination, a frame, a main-shaft rotatably journaled in said frame, a countershaft, a nested pulley assembly mounted on said countershaft and including a loose pulley, a low speed pulley and a high speed pulley, means operatively connecting said low speed pulley to said main-shaft, means operatively connecting said high speed pulley to said main shaft, a single driving belt adapted to run upon each of said nested pulleys, a spring-biased belt-shipper adapted to'engage and shift said driving belt from one to the other of said nested pulleys, means connected to be actuated by said countershaft for moving said belt-shipper to shift the-driving belt from said low speed pulley onto said high speed pulley, and second means operable at predetermined times in the stitching cycle to permit said belt-shipper to shift said driving belt from said high speed pulley onto said low speed pulley and thence onto said loose pulley,

4. A group-stitch sewing machine having, in combination, a frame, a main-shaft rotatably journaled in said frame, a countershaft, a nested pulley assembly mounted on said countershaft and including a loose pulley, a low speed pulley and a high speed pulley, means operatively connecting said low speed pulley to said main-shaft, means operatively connecting said 'high speed pulley to said main-shaft, a single driving belt adapted to run upon each of said nested pulleys, a spring-biased belt-shipper adapted to engage and shift said driving belt from one to the other of said nested pulleys, separate latches for detaining said belt-shipper in its respective running positions, means connected to be actuated by said countershaft for moving said belt-shipper to shift the driving belt from said low speed pulley onto said high speed pulley, and second means operable at predetermined times in the stitching cycle to release said separate latches to permit said belt-shipper to shift said driving belt from said high speed pulley onto said low speed pulley and thence onto said loose pulley.

5. A group-stitch sewing machine having, in combination, a frame, a main-shaft rotatably journaled in said frame, a countershaft, a driven shaft, a nested pulley assembiy mounted on said countershaft and including a loose pulley, a low speed pulley and a high speed pulley, means separately connecting said low speed pulley and said high speed pulley to said main-shaft, a single driving belt adapted to run upon each of said nested pulleys, a spring-biased belt-shipper adapted to engage and shift said driving belt from one to another of said nested pulleys, separate latches for detaining said belt-shipper in its respective running positions, means connected to be actuated by said countershaft for moving said belt-shipper to shift the driving belt from said low speed pulley onto said high speed pulley, and second means actuated by said driven shaft for releasing said separate latches individually to permit said belt-shipper to shift said driving belt from said high speed pulley onto said low speed pulley and thence onto said loose pulley.

6. A group-stitch sewing machine having, in combination, a frame, a main-shaft rotatably journaled in said frame, a countershaft, a nested pulley assembly mounted on said countershaft and including a loose pulley, a low speed pulley and a high speed pulley, means separatel connecting said low speed pulley and said high speed pulley to said main-shaft, a single driving belt adapted to run upon each of said pulleys, a belt-shipper adapted to engage and shift said driving belt from one to another of said nested pulleys, a cam-cylinder mounted upon said countershaft, means actuated by said cam-cylinder for moving said belt-shipper to shift said driving belt from said low speed pulley onto said high speed pulley, and second means automatically actuated to permit the belt-shipper to shift said driving belt from said high speed pulley onto said low speed pulley and thence onto said loose pulley.

'7. A group-stitch sewing machine having, in combination, a frame, a main-shaft journaled therein, a nested pulley assembly including a loose pulley, a low speed pulley and a high speed pulley, means separately connecting said low speed pulley and said high speed pulley with said main-shaft, a driving belt adapted to run on each of said nested pulleys, a stop-motion device including a tilting stop-motion lever, a stop-cam cooperating with said lever to stop said mainshaft in a predetermined angular position, a beltshipper mounted for movement independently of said stop-motion lever, manually controlled means for tilting said stop-motion lever out of stopping position and to move said belt-shipper to shift said driving belt from said loose pulley onto said low speed pulley, means adapted to further move saidbelt-shipper to shift said driving belt onto said high speed pulley, means operable at a predetermined time in said stitching cycle to permit said belt-shipper to shift said driving belt onto said low speed pulley, and means operable at the end of the stitching cycle to permit simultaneous movement of said belt-shipper and said stop-motion lever to shift said driving belt onto said loose pulley and stop the main-shaft in its predetermined angular position.

8. A group-stitch sewing machine having, in combination, a frame, a main-shaft journaled therein, a countershaft, a nested pulley assembly mounted upon said countershaft and including a loose pulley, a low speed pulley and a high speed pulley, means separately connecting said low speed pulley and said high speed pulley with said main-shaft, a single driving belt adapted to run on each of said nested pulleys, a stop-motion device including a tilting stop-motion lever, a stop-cam on said countershaft cooperating with said lever to stop said main-shaft in a predetermined angular position, a belt-shipper mounted for movement independently of said stop-motion lever, manually controlled means for tilting said stop-motion lever out of stopping position and to move said belt-shipper to shift said driving belt from said loose pulley onto said low speed pulley, automatic means connected to be operated by said countershaft to further move said belt-shipper to shift said driving belt onto said high speed pulley, automatic means operable at a predetermined time in said stitching cycle to permit said belt-shipper to shift said driving belt onto said low speed pulley, and automatic means operable at the end of the stitching cycle to permit simultaneous movement of said belt-shipper and said stop-motion lever to shift said driving belt onto said loose pulley and stop the main-shaft in its predetermined angular position.

9, A group-stitch sewing machine having, in combination, a frame, a main-shaft journaled therein, a countershaft, a nested pulley assembly mounted upon said countershaft and including a loose pulley, a low speed pulley and a high speed pulley, means connecting said low speed pulley and said high speed pulley with said main-shaft, a driving belt adapted to run on each of said nested pulleys, a stop-motion device including a tilting stop-motion lever, a stop-cam cooperating with said lever to stop said main-shaft in a predetermined angular position, a belt-shipper mounted for movement independently of said stop-motion lever and spring-biased to stopping position, separate latches for detaining said stopmotion lever and said belt-shipper in their respective running positions, manually initiated means for tilting said stop-motion lever out of stopping position and to move said belt-shipper to shift said driving belt from said loose pulley onto said low speed pulley, automatic means operable to Iurther move said belt-shipper to shift said driving belt onto said high speed pulley, and second automatic means operable for releasing said separate latches individually to permit said belt-shipper first to shift said driving belt from said high speed pulle onto said low speed pulley and second to permit simultaneous movement of said belt-shipper and said stop-motion lever to shift said driving belt onto said loose pulley and stop the main-shaft in its predetermined angular position.

10. A group-stitch sewing machine having, in combination, a frame, a main-shaft journaled therein, a countershaft, a driving shaft adapted to make one complete revolution during each group-stitchcycle, a nested pulley assembly mounted on said countershaft and including a loose pulley, a low speed pulley and a high speed pulley, means connecting said low speed pulley and said high speed pulley with said main-shaft, a driving belt adapted to run on each of said pulleys, a stop-motion device including a tilting stop-motion lever, a stop-cam mounted on said countershaft and cooperating with said lever to stop said main-shaft in a predetermined angular position, a belt-shipper mounted to move independently of said stop-motion lever and springbiased into stopping position, separate latches for detaining said stop-motion lever and said beltshipper in their respective running positions, manually controlled means for tilting said stopmotion lever out of stopping position and moving said belt-shipper to shift said driving belt from said loose pulley onto said low speedpulley, automatic means connected to be operated by said countershaft for moving said belt-shipper to shift said driving belt from said low speed pulley onto said high speed pulley, automatic means connected to be operated by said driven shaft for releasing one of said separate latches to permit said belt-shipper to shift said driving belt from said high speed pulley onto said low speed pulley, and second automatic means connected to be operated by said driven shaft for releasing another of said separate latches to permit simultaneous movement of said belt-shipper and said stopmotion lever to shift said driving belt onto said loose pulley and stop the main-shaft in its predetermined angular position.

11. A buttonhole sewing machine having, in combination, a frame, a main-shaft and a countershaft journaled in said frame, a nested pulley assembly mounted on said countershaft and including a loose pulley, a low speed pulley and a high speed pulley, gearing connecting said low speed pulley and said high speed pulley with said main-shaft, a driving belt adapted to run on each of said nested pulleys, a belt-shipper adapted to engage and shift said driving belt from one to another of said nested pulleys, manually controlled means for moving said belt-shipper to shift said driving belt from said loose pulley onto said low speed pulley, automatic means for movin said belt-shipper to shift said belt from said low speed pulley onto said high speed pulley, said automatic means including a cam on said countershaft, and a bell-crank lever fulcrumed on said machine-frame and having one of its arms connected to said cam and its other arm positioned to engage said belt-shipper to move the same when said bell-crank lever is actuated by said cam, and automatic means operable near the end of the buttonhole stitching cycle fo moving said belt-shipper to shift said driving belt from said high speed pulley onto said low speed pulley and thence onto said loose pulley.

12. A buttonhole sewing machine having, in combination, a frame, a main-shaft and a countershaft journaled in said frame, a, nested pulley assembly mounted on said countershaft and including a loose pulley, a low speed pulley and a high speed pulley, gearing connecting said low speed pulley and said high speed pulley with said main-shaft, a driving belt adapted to run on each of said nested pulleysa belt-shipper adapted to engage and shift said driving belt from one to another of said nested pulleys, manually controlled means for moving said belt-shipp r to shift said driving belt from said loose pulley onto said low speed pulley, automatic means for moving said belt-shipper to shift said belt from said low speed pulley onto said high speed pulley, said automatic means including a pivotally supported lever positioned to engage said belt-shipper, and devices adapted to impart a single rocking impulse during each buttonhole producing cycle to said pivotally supported lever to effect a movement of said belt-shipper, and automatic means operable near the end of the buttonhole stitching cycle for moving said belt-shipper to shift said driving belt from said high speed pulley onto said low speed pulley and thence onto said loose pulley.

13. A buttonhole sewing machine having, in combination, a main-shaft, a countershaft, a nested pulley assembly mounted upon said countershaft and including a high speed pulley, a low speed pulley and a loose pulley, a gear on said high speed pulley, a gear fixed on said mainshaft and in mesh with said gear on said high speed pulley, a gear on said low speed pulley, a gear fixed on said main-shaft in mesh with said gear on said low speed pulley, a driving belt adapted to run on each of said nested pulleys, and timing means effecting a shifting of said driving belt from one to another of said nested pulleys.

14. A buttonhole sewing machine having, in combination, a main-shaft, a countershai't, a

nested pulley assembly mounted upon said countershaft, said nested pulley assembly including a high speed pulley fixed on said countershaft, a low speed pulley formed with an extended hub freely journaled on said countershaft, and a loose pulley freely journaled on said extended hub of said low speed pulley, a gear on said high speed pulley, a gear fixed on said main-shaft and in mesh with said gear on said high speed pulley, a gear on said low speed pulley, a gear fixed on said main-shaft in mesh with said gear on said low speed pulley, a driving belt adapted to run on each of said nested pulleys, and timing means effecting a shifting of said driving belt from one to another of said nested pulleys.

15. A buttonhole sewing machine having, in combination, a rotary main-shaft, a countershaft disposed in juxtaposition in said main-shaft, a nested pulley assembly mounted upon said countershaft, said nested pulley assembly including a high speed pulley fixed on said countershaft, a low speed pulley formed with an extended hub freely journaled on said countershaft, and a loose pulley freely journaled on the periphery of said extended hub, a gear on said high speed pulley, a gear fixed on said mainshait and in mesh with said gear on said high speed pulley, a gear secured on said hub of said low speed pulley, a gear fixed on said main-shaft in mesh with said gear on said low speed pulley, a driving belt adapted to run on each of said nested pulleys, and timing means effecting an automatic shifting of said driving belt from said low speed pulley onto said high speed pulley and subsequently from said high speed pulley onto said low speed pulley and thence onto said loose pulley during each buttonhole-producing cycle.

16. A buttonhole sewing machine having, in combination, a rotary main-shaft, a countershaft disposed in juxtaposition to said main-shaft, a nested pulley assembly mounted upon said countershaft, said nested pulley assembly including a high speed pulley fixed on said countershait, a low speed pulley formed with an extended hub freely journaled on said countershait, and a loose pulley freely journaled on the periphery of said extended hub, a gear on said high speed pulley, a gear fixed on said main-shaft and in mesh with said gear on said high speed pulley to drive said main-shaft at a speed in excess of that of the high speed pulley, a gear secured on said hub of said low speed pulley, a gear fixed on said mainshaft in mesh with said gear on said low speed pulley, a driving belt adapted to run on each of said nested pulleys, timing means effecting an automatic shifting of said driving belt from said low speed pulley onto said high speed pulley and subsequently from said high speed pulley onto said low speed pulley and thence onto said loose pulley, a stop-motion device including a movable stop-motion lever, and a stop-cam mounted adjacent to and resiliently connected with said high speed pulley and cooperating with said stop-motion lever to stop said main-shaft in a predetermined angular position.

1'7. A group-stitch sewing machine having, in combination, a main-shaft, a pulley assembly including at least a loose pulley, a low speed pulley and a high speed pulley, means operatively connecting said low speed pulley to said main-shaft, means operatively connecting said high speed pulley to said main-shaft a single driving belt adapted to run upon each of said pulleys, a beltshipper adapted to engage and shift said driving belt from one to the other of said nested pulleys, manually actuated means operable to move said belt-shipper to shift said belt from said loose pulley onto said low speed pulley, means automaticalily actuated for moving said belt shipper to shift said belt from said low speed pulley onto said high speed pulley, said last named means including a one-revolution switch-cam and a lever actuated by said switch-cam for moving said belt-shipper, and second means automatically actuated to permit the belt-shipper to shift said driving belt from said high speed pulley onto said low speed pulley and thence onto said loose pulley.

18. In a sewing machine having a rotary mainshaft, a change-speed driving mechanism including a low speed driving pulley and a high speed driving pulley, means operativeiy connecting said pulleys to said rotary main-shaft, a single driving belt adapted to run on each of said pulleys one at a time, a belt-shipper adapted to engage and shift said driving belt from one to another of said pulleys, a rotary switch-cam, a lever actuated by said switch-cam and adapted to engage and operate said belt-shipper to move the driving belt from said low speed pulley onto said high speed pulley, means for disconnecting said lever from said switch-cam after said belt-shipper has been moved to shift said belt from said low speed pulley onto said high speed pulley, means permitting said belt-shipper to return said driving belt from said high speed pulley to said low speed pulley when desired, and means to reestablish connective relationship between said lever and said switch-cam whereby said belt-shipper can be actuated to shift the belt from said low speed pulley onto said high speed pulley.

ALFRED R. WOOD.

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