US3585949A

US3585949A - Device for stopping a working element in a given position

Info

Publication number: US3585949A
Application number: US802806*A
Authority: US
Inventors: Joseph Chudner
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-02-27
Filing date: 1969-02-27
Publication date: 1971-06-22
Anticipated expiration: 1988-06-22

Abstract

A device for stopping a working element in a given position. For example, in the case of a sewing machine, the working element is a needle which should always be located in a given position displaced out of the work when the machine stops operating. The device includes a high-speed drive operatively connected with the working element to drive the latter at a relatively high speed during normal operation of the machine. In addition there is a low-speed drive connected with the working element to drive the latter at a relatively low speed, and the operator of the machine can switch over from the high-speed drive to the low-speed drive in preparation for stopping the operation of the machine. A blocking component coacts with the low-speed drive for blocking the transmission of power therefrom to the working element as soon as the latter reaches a given position so that the working element will remain in this latter position. Because the termination of the drive to the working element and the location thereof in the predetermined stopped position takes place only when driving through the low-speed drive, the stressing of the machine components is reduced and the smoothness of the entire stopping operation is enhanced.

Description

United States Patent [72] Inventor Joseph Chudner 2907 Brighton 8th St., Brooklyn, N.Y. 11235 {21] Appl. No. 802,806 [22] Filed Feb. 27, 1969 [45] Patented June 22, 1971 [54] DEVICE FOR STOPPING A WORKING ELEMENT IN A GIVEN POSITION 11 Claims, 10 Drawing Figs.

[52] US. Cl. 112/219, 192/99,192/3.5, 74/512 [51] Int. Cl D05b 69/22 [50] FieldofSearch 112/219,

[56] References Cited UNITED STATES PATENTS 2,332,649 10/1943 Kott 112/219 X 1,926,604 9/1933 Terry... 112/219 2,159,722 5/1939 Bedard 112/219 (A) 2,936,727 5/1960 Ashworth et al 1 12/219 Primary Examiner-41. Hampton Hunter At!orneyBlum, Moscovitz, Friedman and Kaplan ABSTRACT: A device for stopping a working element in a given position. For example, in the case of a sewing machine, the working element is a needle which should always be located in a given position displaced out of the work when the machine stops operating. The device includes a high-speed drive operatively connected with the working element to drive the latter at a relatively high speed during normal operation of the machine. In addition there is a low-speed drive connected with the working element to drive the latter at a relatively low speed, and the operator of the machine can switch over from the high-speed drive to the low-speed drive in preparation for stopping the operation of the machine. A blocking component coacts with the low-speed drive for blocking the transmission of power therefrom to the working element as soon as the latter reaches a given position so that the working element will remain in this latter position. Because the termination of the drive to the working element and the location thereof in the predetermined stopped position takes place only when driving through the low-speed drive, the stressing of the machine components is reduced and the smoothness of the entire stopping operation is enhanced.

PATENTEuJuuzmm: 3,585,949

sum 3 0F 4 ATTORNEYS DEVICE FOR STOPPING A WORKING ELEMENT IN A GIVEN POSITION CROSS REFERENCE TO RELATED APPLICATION The present application discloses further developments of devices of the type shown in copending application Ser. No. 681,470, filed Nov. 8, 1967 and entitled STRUCTURE FOR STOPPING A MACHINE IN A GIVEN POSITION now US. Pat. No. 3,534,845, dated Oct. 20, 1970.

BACKGROUND OF THE INVENTION The present invention relates to devices for stopping the working element of a machine in a given position.

Thus, the present invention is applicable, for example, to sewing machines in order to situate the needle thereof in a predetermined position out of the work when the operation of the machine is terminated.

There are various known ways of locating such a working element at a given location when the operation thereof is terminated. Thus, it is very well-known that with sewing machines the operator can simply manually turn a flywheel or the like until the needle is located at a preselected position. In addition, there are automatic devices which operate to terminate the movement of a working element when the latter has reached a given position. However, structures of this latter type have certain drawbacks. For example, it is possible to use brakes to stop the operations, but such devices do not operate smoothly and often grab or seize so as to provide a sudden impact-type of termination of the movement of the machine components. The result is very great stressing of the components and sudden terminations of movement resulting in loud banging and jerky operation with parts rapidly becoming worn and loose so that considerable maintenance is required.

SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide a construction which will avoid the above drawbacks.

In particular, it is an object of the invention to provide a construction which will enable a machine element to be stopped in a given position with a smooth impact-free type of operation.

Thus, in the specific case of the needle of a sewing machine, it is an object of the invention to provide a construction capable of stopping the needle at a location where it is out of the work while at the same time bringing the operating parts of the sewing machine gradually and smoothly to a stop.

Also, it is an object of the invention to provide an assembly which will accomplish the above objects and which can be attached very conveniently and inexpensively to existing structures.

In addition it is an object of the invention to provide a construction of this type which is relatively simple and inexpensive to manufacture and which requires minimum maintenance once it is set up for operation.

According to the invention a high-speed drive means transmits a drive to a working element of a machine so as to drive the working element during normal operations. A low-speed drive means is also provided for coaction with the working element to drive the latter at a relatively low speed in preparation for stopping the operation of the working element. A means is provided for enabling the operator to switch over from the highspeed to the low-speed drive means preparatory to stopping the operation of the working element. In addition, a blocking means coacts with the low-speed drive means to terminate transmission of a drive therefrom to the working element when the latter has reached the predetermined given position at which it is to be stopped.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. I is a simplified perspective view of a sewing machine provided with structure of the invention;

FIG. 2 shows the structure of FIG. 1 in a side elevation as it appears from the right of FIG. 1;

FIG. 3 is a sectional plan view of the structure of the invention taken along line 3-3 of FIG. 2 in direction of the arrows and showing the structure at a scale larger than that of FIG. 2;

FIG. 4 is a sectional elevation of the structure of FIGS. 2 and 3 taken along line 4-4 of FIG. 3 in the direction of the arrows;

FIG. 5 shows the structure of FIG. 4 in a position taken by the parts during operation;

FIG. 6 is a longitudinal sectional elevation of the structure taken along line 6-6 of FIG. 5 in the direction of the arrows;

FIG. 7 is a fragmentary elevation at a scale larger than FIG. I showing the manner in which treadle operation is used to control the drive from a motor;

FIG. 8 is a longitudinal section elevation taken along line 8-8 of FIG. 7 in the direction of the arrows and showing further details of the structure of FIG. 7;

FIG. 9 is a longitudinal sectional elevation taken along line 9-9 of FIG. 1 in the direction of the arrows and showing, at an enlarged scale as compared to FIG. 1, part of the transmission from the treadle to the controls of the structure of the invention; and

FIG. 10 is a diagrammatic representation of the needle of the sewing machine.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings, FIGS. 1 and 2 show a suitable table 12 which carries the sewing machine structure as well as the structure of the invention and at which the operator is seated during sewing operations. The table includes the legs 14 as well as the table top 16. Between the legs 14 there is a baseplate 18 formed with suitable openings to provide an adjustable location for the treadle 20. This treadle 20 has at its ends coaxial pivot pins received in bearing openings of ears 22 so that in this way the treadle 20 is supported for swinging movement. During operations the operator will with a toe portion of a foot move the inner end 24 of the pedal 20 downwardly in order to start the operation of the machine. To stop the operation the operator will, with a heel portion of a foot, move the front or outer end 26 of the pedal downwardly so as to stop the operation of the machine.

The machine table 12 has fixed to the underside of the tabletop I6 a main driving motor 28 which is turned on by a master switch 31 also fixed to the underside of the tabletop I6. Whenever this switch is closed the electric motor 28 operates. Referring to FIG. 7, as well as FIG. 1, the motor 28 includes in a well-known way, in its interior, a brake which releases the drive from the motor when the brake is disengaged or which prevents the motor from transmitting a drive when the brake is engaged. This known brake assembly is operated by a swinglever 30 having a U-shaped end portion 32 pivoted to the motor as by pivot bolts 34. The lower horizontal arm of the swing-lever 30 is provided with a series of openings 36. Also, the lever 30 carries a control rod 38 passing freely through an opening of a plate 40 which is fixed to the housing of the motor 28. On the left side of the plate 40, as viewed in FIG. 7, the rod 38 carries a coil spring 42 against which a wingnut 44 presses so as to control the compression of the coil spring 42, the rod 38 being suitably threaded to receive the nut 44 as well as a nut 46 at its opposite end where it extends through an opening of the lever 30. The compression of the spring 42 is such that it tends to displace the rod 38 to the left, as viewed in FIG. 7, thus swinging the lever 30 in a clockwise direction to locate the brake of the motor 28 in the position where it prevents transmission of the drive to the motor-driven pulley 48.

As may be seen from FIG. 8, a bolt 50 extends through one of the openings 36 of the lever 30 and is fixed in position by a nut 52. The bolt passes through an opening of a plate 54 having at its left end, as viewed in FIG. 7, rearwardly directed ears overlapping the upper and lower edges of the lever 30 and having setscrews 56 threaded through bores of these ears and engaging the upper and lower edges of the lever 30 to center the plate 54 on the lever 30 particularly in the case where the latter has a width which is less than the distance between the ears which carry the screws 56. The plate 54 is itself provided in its corner regions with threaded bores which receive screws 58 which pass through openings of a guide plate 60 having at its right and left edges as viewed in FIG. 7, flanges engaging the front surface of lever 30 visible in FIG. 7. Thus, the plate 60 is of a substantially U-shaped cross section and forms a guide for an elongated bar 62. This bar 62 can be fixed at any selected elevation by tightening of a setscrew 64 which passes into a threaded bore formed centrally in the guide plate 60 at a central boss thereof.

The elongated bar 62 has a widened upper end portion 66 giving the bar a substantially T-shaped configuration as is apparent from FIG. 7.

A lever 68 is pivoted at 70 to the upper right corner portion of the widened end 66 of the bar 62, as viewed in FIG. 7. For example, this upper portion of the bar is formed with a longitudinal notch having a top open end and receiving the right elongated portion of the lever 68, as viewed in FIG. 7, and this longitudinal notch or groove which is accessible through the top end of the bar is also formed with a transverse notch or groove 72 of a substantially curved configuration in cross section so as to receive part of a roller 74 freely turnable on a pin 76 forming part of a bolt which extends through an opening of the lever 68 in the manner shown in FIG. 8.

When the parts are in the position of rest with the transmission from the motor 28 to the pulley 48 interrupted, the roller 74 engages the underside of the motor housing and the lower end of the bar 62 is located at the elevation of the line 78 (FIG. 7). This is the rest or neutral position of the parts. The left free end portion of the lever 63, which is inclined downwardly toward the left, as viewed in FIG. 7, is pivotally connected through suitable fittings to the top end of an elongated rod 80, the bottom end of which is pivoted to a rearwardly directed ear of an elongated bar 82 fixed to the rear end 24 of the treadle 20. Thus, when the rear or inner end 24 of the treadle is moved down, the parts will assume the solid line position indicated in FIG. 7 where the drive from the motor 28 to the pulley 46 is released, and at this time the pulley 48 will rotate. However, it is also possible for the operator to displace therod 80 upwardly, when depressing the forward portion 26 of the treadle 20, and now the lever 68 will rock about the pin 76 while the roller 74 remains in engagement with the motor housing, so that the pivot 70 will move down and displace the bar 62 downwardly. In this way the parts will again assume the position shown in FIG. 7 except that now the rod 60 and the lever 68 together with the roller 74 have the dot-dash line position as shown in FIG. 7. When the drive from the motor 28 to the pulley 48 is released so that the pulley 48 is driven the bar 62 has its lower end situated at the elevation of the line 84 shown in FIG. 7, so that irrespective of whether the rod 80 is moved up or down, the bar 62 will be displaced from the neutral position where the bottom end of the bar is at the elevation of the line 78 to the operating position where the bottom end of the bar is at the elevation of the line 84 shown in FIG. 7. In this way operation of the treadle 20 in either direction will result in displacement of the swing lever 30 in the same direction to release the brake so that the drive is transmitted from the motor 28 to the pulley 48. When the operator does not depress either the inner rear edge 24 or the front edge 26 of the treadle 20, the spring 42 acts to maintain the parts in the neutral position where the drive from the motor 28 to the pulley 48 is interrupted.

The pulley 48 drives an endless belt 86 which extends up freely though a slot 88 formed in the tabletop 16 (FIG. 3 and 6). This pulley belt 86 passes around a pulley 90 which forms an input transmission element of high and low-speed drive transmissions described below, so that both of these latter transmissions have the input element 90 in common. As may be seen from FIG. 6 in particular, the pulley is fixed to a free end of a rotary hollow shaft 92 which extends into a housing 94 of the unit of the invention and is supported for rotation by any suitable bearings carried by the end wall 96 and the intermediate wall 98 of the housing 94. In order to prevent axial displacement of the hollow shaft 92 a collar 100 is fixed thereto in the interior of the housing 94 engaging the inner surface of the wall 96.

The left side portion of the pulley 90, as viewed in FIG. 6, forms a component 102 of a slip clutch 104. This slip clutch includes a second component 106 which is fixed to the right side end face, as viewed in FIG. 6, of a pulley I08 which is fixed to a rotary shaft Ill) which extends slidably through the hollow shaft 92 so as to be freely turnable therein while supported thereby for rotary movement. This pulley 108 forms an output member of the high-speed drive means of the invention as well as of the low-speed drive means of the invention so that both of these drive means have the common input transmission element 90 and the common output transmission element 108. The inner surface of the belt-receiving groove of the pulley MP8 is suitably toothed so as to coact with the inner teeth of an endless transmission belt 1112 as shown in FIG. 2 extending up to a driving pulley of the operating head of the sewing machine. This operating head is of a conventional construction known in the art and not forming any part of the present invention. Through the operating head the needle I16 (FIG. 10) which forms the working element is reciprocated between the solid and dot-dash line positions shown in FIG. E0, the parts coacting with a looper 118 in a manner wellknown in the art. When the operations are stopped the needle 1116 should be located out of the work 1120 in the solid line position shown in FIG. 10.

The high-speed drive means of the invention includes only the input transmission element 90, the output transmission element 108, and the transmission therebetween which is formed by the slip clutch 11045. When this clutch is engaged, the drive is transmitted directly from input element 90 through clutch 1104 to the output element 108 and then from the latter through the belt M2 to the machine. This is the transmission which operates during normal operation of the machine and it operates the machine at a relatively high speed on the order of 2800 rpm. for example. Of course, this speed can be regulated with suitable depression of the treadle as is well known. Thus if the operator depresses the inner edge 24 to a greater extent the speed is increased while if the inner end 24 of the treadle is depressed to a lesser extent the speed will be diminished, but during normal operations a relatively high speed is provided for the machine.

The low-speed drive means includes a pulley 1114 also fixed to the shaft 92 for rotation therewith, this pulley 1M being coaxial with the pulley 90 but of a substantially smaller diameter. The pulley llM drives a belt 116 which extends around a pulley 1118 of relatively large diameter, as is apparent from FIG. 3. This pulley 1118 is fixed to the outer end of the elongated shaft ll20 also supported for rotary movement by suitable bearings carried by the housing 94. The shaft I20 fixedly carries at its inner end, adjacent to the removable end wall 122 of the housing 94, a pulley 124 (FIGS. 3 and 5). The wall 326 of the housing 94 is formed with a suitable opening to provide clearance for the pulley 124. This pulley 126, which is of a substantially smaller diameter than the pulley 118, drives an endless belt 128 which extends around a pulley 130 which is freely turnable on the right end of the shaft 110, as viewed in FIG. 6. This pulley 130 carries at its left surface, as viewed in FIG. 6, a layer of a friction material 132 so that this assembly forms part of a second slip clutch 134. This second slip clutch I34 includes a second component 1136 in the form of a disc fixed to the shaft llllO for rotation therewith and carrying a positioning pin 138 which rotates with the disc 136 for a purpose described below. A coil spring M0 surrounds the part of the shaft Ill!) extending between the wall 98 and the disc I36 and pressing against the wall 98 and the disc I36 so as to urge shaft ill) to the right, as viewed in FIG. 6. In this way the spring 140 acts to maintain the slip clutch 104 engaged so that normally the highspeed drive means will act to operate the needle 116. However, the components formed by the

pulleys

114, 118, 124, and 130 form together with the slip clutch 134 part of a stepdown transmission for driving the shaft 110 at a much slower speed, as will be apparent from the description which follows.

As is apparent from FIG. 6, the pulley 130 is fixed to a sleeve 142 which extends slidably through an opening in the removable wall 122 of the housing 94 and which is slidable on the right end of the shaft 110, as viewed in FIG. 6. A small spring washer 144, which is not essential, is situated between

elements

130 and 136 to lightly displace element 130 away from element 136 so as to maintain the clutch 134 disengaged. The outer end of the sleeve 142 is closed by an end wall 146 situated next to the inner end of a threaded stud 148 which extends through a threaded bore formed at the upper end of the rock lever 150 supported for swinging movement on a pin 152 which extends between a pair of ears 154 fixed to and projecting from the outer surface of the removable closure wall 122 of the housing 94. The top surface of the bottom wall 156 of the housing 94 is suitably grooved, as shown in FIG. 6, to accommodate the rock lever 150 for swinging movement about the pin 152. The rock lever 150 can be turned from the position shown in FIG. 6 in a counterclockwise direction around the pin 152, as viewed in FIG. 6, so as to press the left end of the screw 148, as viewed in FIG. 6, against the sleeve 142 to displace the pulley 130 to the left, as viewed in FIG. 6, along the shaft 110. The result is not only that the clutch 134 will become engaged, but also that the entire shaft 110 will be displaced slightly to the left, as viewed in FIG. 6, to a distance sufficient to disengage the clutch 104. This is the position in which the parts are shown in FIG. 3. At this time the drive through the high-speed drive means is interrupted and instead the drive takes place through the low-speed drive means. In this way the speed of operation of the machine is reduced, for example, to the order of 600 rpm.

The left free end of the rock lever 150, as viewed in FIG. 6, extends through a vertically extending slot 150 which is formed in the wall 96 of the housing 94. At the exterior surface of the wall 96, the left free end of the lever 150 is overlapped by the inner end of a swingable operating finger 160 which is fixed intermediate its ends to a rotary shaft 162 also supported for rotary movement by any suitable bearings and extending parallel to the shaft 110 and through the wall 98 which is also vertically slotted to provide for free swinging of the lever 150. The shaft 162 also fixedly carries a collar 164 to prevent axial displacement of the shaft 162. The right end of the shaft 162, as viewed in FIG. 6, extends through and beyond the intermediate wall 98 to the right side thereof. as viewed in FIG. 6,where this shaft 162 carries control elements referred to in greater detail below,

The slot 08 through which the belt 86 extends is made wide enough to accommodate an elongated rod 166 which is pivoted at its top end to end of the lever 160 which is distant from the rock lever 150. This rod 166 extends freely through the slot 80 and is threaded at its bottom end into the central threaded bore of a threaded closure plug 168 (FIG. 9) which closes the top end of a sleeve 170 whose bottom end is closed by a second axially bored threaded closure plug 172. A rod 174 is slidable through the bore of the lower plug 172 and extends at its lower region through the interior of a clamping sleeve 176 which is of an elliptical configuration. As may be seen from FIGS. 1 and 2 this sleeve 176 also receives in its interior the upper end of an elongated rod 178. The bottom end of this rod is pivoted to the rearwardly directed ear 180 of the bar 82.

The portions of the

rods

174 and 178 which overlap within the sleeve 176 can be clamped together by way of a screw 182 threaded through a wall of the sleeve 176. In this way an adjustment of the total length of the assembly of the rods can be achieved.

As may be seen from FIG. 9, the upper end of the rod 174 is fixed to a piston 184 which slides within the hollow cylindrical sleeve 170. Below this piston a coil spring 186 is coiled around the part of the rod 174 which is within the sleeve 170. A second coil spring 188 is compressed between the plug 168 and the piston 184. In this way the coil springs 186 and 188 coact to provide longitudinal transmission of motion from the rod 174 to the rod 166, when the rod 174 is moved upwardly, with the spring 188 at this time providing a yieldability in this motion transmission. On the other hand when the rod 174 is moved downwardly it is the spring 186 which tends to be compressed to provide a resiliently yieldable transmission from the downwardly moving rod 174 to the sleeve 170 and from the latter to the rod 166.

Thus, with this construction when the operator depresses the inner or rear edge 24 of the treadle 20, the rod 166 will be moved downwardly to swing the lever 160 and the shaft 162 therewith in a clockwise direction, as viewed in FIG. 5, so that these components will now have the position shown in FIG. 5 with the innerend of the finger which forms lever 160 situated at an upper elevation enabling the spring to expand to the position shown in FIG. 6 so that the high-speed drive is engaged at this time and the operations proceed in the normal way. On the other hand, when the front edge 26 of the treadle is depressed, the rod 166 will be raised to locate the finger which forms the lever in the position shown in FIG. 4, and now the end of the finger 160 distant from the rod 166 depresses the left free end of the rock lever 150, as viewed in FIG. 6, so that at this time the clutch 134 is engaged and the clutch 104 is disengaged, and the parts have the position shown in FIGS. 3 and 4 where the sewing operations are terminated. Therefore, the treadle 20 and the connection between the latter and the lever 160 as well as the lever 150 form a means for switching over between the high-speed drive means and the low-speed drive means.

The intermediate wall 98 carries a pivot bolt 190 which serves to pivotally support a block 192 which forms part of a blocking means of the invention. This block 192 carries a bolt around which one end of a coil spring 194 is hooked. The opposite end of this spring is joined by a screw 196 to the wall 126 of the housing 94. Thus the spring 194 urges the block 192 in clockwise direction about the pivot 190 as viewed in FIG. 4. The wall 90 fixedly carries a pin 198 which acts as a stop to locate the block 192 in the position illustrated in FIG. 4.

At its top end the block 192 fixedly carries a relatively heavy coil spring 200 of relatively short length. When the block 192 engages the pin 198 the spring 200 is in the path of turning movement of the positioning pin 138 fixed with a disc 136, so that during a rotation of less than one revolution the pin 138 will engage the spring 200 and stop the transmission to the needle 1 16. When the pin 138 engages the spring 200 with the parts in the position of FIG. 4, the needle 116 is necessarily located in the solid line position of FIG. 10 out of the work.

An elongated control finger 202 is bolted to the right side surface of the block 192 as viewed in FIGS. 4 and 5, and this finger 202 terminates distant from the block 192 in a tapered tip 204. This tip 204 is adapted to coact with a tooth 206 of a swingable latch member 208 pivoted on the wall 98 by a pivot screw 210. A wire spring 212 is coiled about a screw 214 carried by the wall 98 and is connected at one end to a pin carried by the latch 208 so as to urge the latter in a counterclockwise direction as viewed in FIGS. 4 and 5, around the pin 210.

The shaft 162 is fixed, as by a setscrew 216, with a control block 218 which fixedly carries an elongated control finger 220. This control finger 220 extends beneath a perpendicular The parts may be assumed as having the rest positions shown in FIGS, 3 and 4. At this time the rod 166 is in its upper position and the pin 220 is in the lower position shown in FIG. 4. The spring 194 holds the block 192 against the pin 198 and the positioning pin 138 is on top of the spring 200.

In order to start the operation the operator will depress the inner or rear edge 24 of the threadle so as to lower the rod 166 and swing the lever 160 into the position shown in FIG. 5. The result is that the pin 220 engages and displaces the pin 222 so as to swing the block 192 in opposition to the spring 194 in a counterclockwise direction thus displacing the tapered tip 204 of the finger 202 above the latch tooth 206 of the latch 208. Now this latter tooth 206 will coact with the tip 204 of the finger 202 to prevent return of the block 192 to the position shown in FIG. 4, so that the parts will remain operating. The upward movement of the end of the lever 160 distant from the rod 166 enables the left free end of the lever 150 as viewed in FIG. 6, to move upwardly, so that the spring 140 can expand and engage the clutch 104 so that the high-speed drive means operates the needle. At this time the clutch 134 is disengaged.

In this way the sewing operations will be carried out. When it is desired to interrupt these operations the operator will depress the forward edge 26 of the treadle 20. The rod 166 will now return to the position shown in FIG. 4. At the same time the pin 226 will turn in a counterclockwise direction, as viewed in FIG. 4, around the axis of the shaft 162, and the pin 226 will at this time engage the surface defining the slot 224 in order to cam the catch 208 in a clockwise direction around the pin 210 in opposition to the spring 212 so as to displace the latch tooth 206 away from the tapered tip 204 of the finger 202 and thus release the block 192 to the spring 194 which now swings the block into engagement with the pin 198 so as to locate the spring 200 in the path of turning movement of the pin 138.

At the same time the end of the lever 160 distant from the rod 166 has moved down so as to swing the lever 150 in a counterclockwise direction about the pin 152, as viewed in FIG. 6, thus causing the stud 148 to engage the clutch 134 while displacing the shaft 110 slightly to the left, in opposition to the spring 140, so as to disengage the clutch 104. In this way the drive has been switched over from the high-speed drive means to the low-speed drive means and the pin 130 turns at this lower speed with the disc 136 until the pin 130 engages the spring 200 so as to stop the needle 116 in the solid line position shown in FIG. 10.

it will be recalled that during this time the lever 63 has been displaced between the solid and dot-dash line positions shown in FIG. 7 while the swing lever has in both cases been turned in the same direction so that the only difference is that when the lever 68 has the dot-dash line position of FIG. 7 the low-speed drive means is operative while when the lever 68 has the solid line position of FIG. 7 the high-speed drive means is operative. Upon release of the treadle the spring 42 will return the lever 30 to a position where the drive from the motor 28 to the pulley 40 is interrupted so that the machine drive will stop.

Of course, the operator need only depress the edge 24 of the treadle 20 in order to again resume the normal operations. Now the tip of the finger 202 will again be displaced upwardly beyond the tooth 206 of the latch 208, and even if the treadle is released without pushing down on the edge 26, the tip of the finger 202 engage the tooth 206 to maintain the parts operating at their normal speed which may, however. be increased by further depression of the edge 24 so as to locate the pin 220 in the position of FIG. 5, for example, where it coacts with the pin 222 to locate the finger 202 upwardly beyond the latch 206.

As may be seen from FIGS. 3-6, the shaft 162 fixedly carries a radially extending lever 230 which is pivotally con nected at its upper free end to an elongated rod 232 which extends through an opening of the wall 126 out to the exterior of the housing 94. At its exterior end portion the rod 232 carries locknuts 234 which engage one end of the spring 236 coiled around the rod 232 and pressing against the exterior surface of the wall 126. Thus the spring 236 acts through the

linkage

232, 230 to urge the shaft 162 to turn in a counterclockwise direction, as viewed in FIGS. 4 and 5. This construction serves to balance to some extent the weight of the treadle so that it is easier to swing the treadle 20.

As is particularly apparent from FIG. 2, the housing 94 and all of the structure carried thereby forms a unit which can be independently mounted on the table 16 at a position with respect to the sewing head which will enable the belt 112 to extend around a toothed pulley fixed to the drive shaft of the sewing head. Of course, the rod 166 will be separately fastened to the lever which form part of the unit carried by the housing 94. In this simple way the entire structure of the invention can readily be attached to an existing sewing machine.

Among the advantages of the structure of the invention are not only the simplicity of the structure and the reliability of the operation thereof, as well as the ease with which the structure is assembled with an existing machine, but in addition the termination of the operations will necessarily take place only when the lower-speed drive means is operating so that when the blocking means formed by the block 192 and spring 200 becomes situated in the path of movement of the positioning pin 138, this latter pin is necessarily turning at a relatively slow speed so as to engage the spring 200 to bring the parts to a stop in a relatively smooth, impact-free manner positioning the needle 116 out of the work and at the same time eliminating any sudden stressing of the components.

Iclaim:

1. In a machine which has a working element which is to be located in a given position when it does not operate, highspeed drive means for transmitting a relatively high-speed drive to the working element during normal operation of the machine, low-speed drive means for transmitting a drive of a lower speed to the working element only in preparation for stopping the operation thereof, means coacting with both of said drive means for switching over from said high-speed to said low-speed drive means preparatory to stopping the operation of said working element, each of said drive means having an operating and a nonoperating position, said low-speed drive means automatically assuming its operating position in response to changing of said high-speed drive means from its operating to its nonoperating position and said high-speed drive means automatically assuming its operating position in response to changing of said low-speed drive means from its operating to its nonoperating position, so that at any given moment one of said drive means is in its operating position, and blocking means coacting with said low-speed drive means for blocking, whenever said low-speed drive means assumes its operating position, the transmission of a drive from the latter to the working element when the working element has been located in said given position by said low-speed drive means, the latter drive means thus operating only during stopping of the working element to drive the latter at said lower speed until said blocking means blocks the transmission of the drive from said low-speed drive means to said working element, said high and low speed drive means both having a common input transmission component and a common output transmission component.

2. The combination of claim 1 and wherein said high-speed drive means has a direct transmission between said common input and output transmission components and said low-speed drive means has a stepdown transmission between said input and output components.

3. The combination of claim 2 and wherein said stepdown transmission of said low-speed drive means includes a slip clutch and a driven element driven thereby, said blocking means being positioned in the path of movement of said driven element to stop the movement thereof when said working element reaches said given position and said slip clutch slipping when said driven element engages said blocking means.

4. The combination of claim 3 and wherein a high-speed slip clutch forms the direct transmission between the input and output transmission components.

5. The combination of claim 3 and wherein a means for switching from said low-speed to said high-speed drive means acts on said blocking means to displace the latter away from said driven element to release the drive to said working element.

6. The combination of claim 5 and wherein a catch means coacts with said blocking means for preventing return of the latter to a position where it is located in the path movement of said driven element.

7. The combination of claim 6 and wherein a spring means urges said blocking means to said position in the path of movement of said driven element and the means for switching from said high-speed to said low-speed drive means coacting with said catch means to release the latter so as to release said blocking means to said spring means to be displaced thereby to said blocking position.

8. The combination of claim 1 and wherein a driving motor is operatively connected with said common input component for driving the latter, and operator-actuated means coacting with said driving motor for releasing the latter for operation both when operating through said high-speed drive means and when operating through said low-speed drive means.

9. The combination of claim 8 and wherein said working element is a needle of a sewing machine, said operator-actuated control means including a swing-lever having a neutral rest position when a drive is not transmitted from said driving motor to said common input component, a treadle, and a linkage means interconnecting said treadle with said swing lever for swinging the latter in the same direction when the treadle is turned in one direction to actuate the high-speed drive means and when said treadle is turned in an opposite direction to actuate the low-speed drive means.

10. The combination of claim 8 and wherein the means for switching between said high-speed and low speed drive means includes an elongated switching component operatively con nected with said treadle to move in one direction when said treadle is turned in one direction and to move in an opposite direction when said treadle is turned in the opposite direction.

11. The combination of claim 1 and wherein said working element is a sewing machine needle, an operating head assembly connected to the needle for operating the latter, said highand low-speed drive means together with said blocking means forming part of a unit separate from said operating head, and transmission means transmitting the drive from said unit to said operating head so that said unit can be separately assembled with a sewing machine.

Claims

1. In a machine which has a working element which is to be located in a given position when it does not operate, high-speed drive means for transmitting a relatively high-speed drive to the working element during normal operation of the machine, low-speed drive means for transmitting a drive of a lower speed to the working element only in preparation for stopping the operation thereof, means coacting with both of said drive means for switching over from said high-speed to said low-speed drive means preparatory to stopping the operation of said working element, each of said drive means having an operating and a nonoperating position, said low-speed drive means automatically assuming its operating position in response to changing of said high-speed drive means from its operating to its nonoperating position and said high-speed drive means automatically assuming its operating position in response to changing of said low-speed drive means from its operating to its nonoperating position, so that at any given moment one of said drive means is in its operating position, and blocking means coacting with said low-speed drive means for blocking, whenever said low-speed drive means assumes its operating position, the transmission of a drive from the latter to the working element when the working element has been located in said given position by said low-speed drive means, the latter drive means thus operating only during stopping of the working element to drive the latter at said lower speed until said blocking means blocks the transmission of the drive from said low-speed drive means to said working element, said high and low speed drive means both having a common input transmission component and a common output transmission component.

10. The combination of claim 8 and wherein the means for switching between said high-speed and low-speed drive means includes an elongated switching component operatively connected with said treadle to move in one direction when said treadle is turned in one direction and to move in an opposite direction when said treadle is turned in the opposite direction.

11. The combination of claim 1 and wherein said working element is a sewing machine needle, an operating head assembly connected to the needle for operating the latter, said high- and low-speed drive means together with said blocking means forming part of a unit separate from said operating head, and transmission means transmitting the drive from said unit to said operating head so that said unit can be separately assembled with a sewing machine.