US3565027A

US3565027A - Tension and releasing means for sewing machines

Info

Publication number: US3565027A
Application number: US856965A
Authority: US
Inventors: Robert F Miller; Roy E Miller
Original assignee: Reece Corp
Current assignee: Reece Corp
Priority date: 1965-02-15
Filing date: 1969-09-11
Publication date: 1971-02-23
Anticipated expiration: 1988-02-23
Also published as: SE315471B; DE1485159A1; GB1112743A; GB1112741A

Abstract

The present sewing thread tension and releasing attachments are attachable to a sewing machine and operate to normally maintain a tension on the thread being fed to sewing machine needle by passing the thread between a pair of discs resiliently held together and at times pneumatic means are operated to separate said discs to release the thread whereupon further pneumatic means pull the thread towards the needle to permit the severing of the thread from a work piece.

Description

UnitedStates Patent Robert F. Miller Camp Hill; Roy E. Miller, Mechanicsburg, Pa. 856,965 Sept. 1 1, 1969 Feb. 23, 1971 The Reece Corporation Waltharn, Mass. Continuation-impart of application Ser. No.

432,721, Feb. 15, 1965, now Patent No. 3,360,002.

Inventors Appl. No. Filed Patented Assignee TENSION AND RELEASING MEANS FOR SEWING MACHINES 3 Claims, 21 Drawing Figs.

U.S. Cl 112/255, 242/150 Int. Cl D05!) 47/00 Field of Search 112/255, 254, 245; 242/150 [56] References Cited UNIT ED STATES PATENTS 2,610,813 9/1952 Campbell 242/150 2,646,944 7/1953 Heffelfinger 242/150 3,364,889 1/1968 Wiener 112/245 Primary Examiner-Patrick D. Lawson Assistant Examiner-George l-l. Krizmanich Attorney-Linton & Linton ABSTRACT: The present sewing thread tension and releasing attachments are attachable to a sewing machine and operate to normally maintain a tension on the thread being fed to sewing machine needle by passing the thread between a pair of discs resiliently held together and at times pneumatic means are operated to separate said discs to release the thread whereupon further pneumatic means pull the thread towards the needle to permit the severing of the thread from a work piece.

TENSION AND RELEASHWG MEANS FOR SEWING MACHINES The present invention is a continuation-in-part of applicants copending application Ser. No. 432,721, filed Feb. 15, I965, now U.S. Pat. No. 3,360,002.

The present invention is concerned with an improvement in sewing machines and more particularly is directed to apparatus for automatically controlling the operation of the sewing machine and severing the sewing thread.

The principal object of the present invention is toprovide a apparatus attachable to conventional sewing machines which apparatus while under the control of an operator, will automatically position the needle, raise and lower the presser foot, properly tension the sewing thread, and sever said sewing thread and including a control for starting, speeding up, slowing down or stopping the operation of the sewing machine.

A further important object of the invention is to provide means of for modifying conventional sewing machines by the addition of reliable equipment which results in faster and simpler sewing operations and automatically positions the sewing needle and cuts the thread giving the operator the choice of putting many stitches or one single stitch in at a time into the work piece before automatically severing the thread therefrom.

Another important object is to provide means for automatically positioning the needle bar with the needle at its top position or at its lowermost position and with'means for stopping the sewing machine when the needle is in its up position breaking an electrical. circuit connected to said positioning means whereupon the operator can energize said electrical circuit for down positioning said needle bar and lifting the presser foot allowing the operator to turn the work piece around the needle.

A further object of the invention is to provide means for automatically and properly cutting thesewing thread between the thread handling system and the work piece when each sewing step of the work piece is completed. Further objects of the invention will be in part obvious and in part pointed out in the following detailed description of the accompanying drawings in which:

FIG. I is a front perspective view of a conventional sewing machine with the apparatus of the present invention connected thereto.

FIG. 2 is an enlarged perspective view of the needle bar carrying end of a sewing machine ann modified according to the present invention.

FIG. 3 is an enlarged front elevation of a part of a sewing machine in accordance with the present inventiorrwith elements removed to show the sewing machine drive.

FIG. 4 is an end view taken from the right of FIG. 3.

FIG. 5 is an enlarged sectional view taken on line 5-5 of FIG. 3.

FIG. 6 is a cross-sectional view taken on line 6-6 of FIG. 3

and laterally of the sewing machine bed showing the positioning cylinder of the present apparams.

FIG. 7 is a greatly enlarged detail view of the needle positioning control with its cap removed.

FIG. 7a is an exploded perspective view of the synchronizer valve bracket and roller and handwheel.

FIG. 8 is a greatly enlarged cross-sectional view taken on line 8-8 of FIG. 6.

FIG. 9 is an end view of the slip clutch partially shown in FIG. 8.

FIG. 10 is an enlarged top view of the sewing thread cutoff.

FIG. 11 is a cross-sectional view taken on line 11-11 of FIG. 11.

FIG. 12 is a cross-sectional view taken on line 12-12 of FIG.

FIG. I is an end view of the thread cutoff tubes. FIG. 13 is a greatly enlarged sectional view taken on line 13-13 of FIG. 2.

FIG. 14 is a schematic diagram of the pneumatic and electrical system of the present apparatus.

FIG. IS-is a partial cross-sectional view taken on line 15-15 of FIG. 4 showing the rear of the sewing machine and the presser foot controls.

FIG. 16 is a wiring diagram of the apparatuswhen the needle is up and presser foot raised.

FIG. 17 is a wiring diagram of the apparatus when the needle is down.

FIG. 18 is an enlarged view of the knee switch forming part of the present apparatus. Referring now more particularly to the accompanying drawings in which like and corresponding parts are designated by similar reference characters, LA and LB designate right and standard legs and LC and LD the left hand standard legs. E is a rod extending between and connected to said standards. with a treadle F having a tube G rotatably mounted on rod E. H is a sewing machine bed supported by said standards whilel is an upright mounted on said bed and having crossarm J supporting rod K on which is rotatably mounted a spool L of thread M. Guide arm N is also mounted on upright I and has eye 0 through-which thread Mi passes to pin P on the cantilever arm R of a conventional sewing machine generally designated Q. Said sewing machine slideably supports needle bar S with needle T and presser foot U.

Said sewing. machine hasia drive shaft hand wheel V around which extends drive belt W. X is the bed plate of the sewing machine and AA a bobbin.

The above elements A to- AA inclusive are conventional structures for sewing machines and supporting structure therefor.

Link I is pivotally connected at one end to bearing 2 carried by treadle F and pivotally connected by stub axle 3 to one end of a second link 4. 1

Link 4 has an arm 5 fixedly connected thereto and a bent end 6 while arm 5 is pivotally connected by'pin7 to the piston rod 8 of a pneumatic brakecylinder 9 to which is attached a solenoid valve l0. Arm I1 is fixedly connected at one end to brake cylinder 9 and pivotally connected by pins 13 to the control yoke 13a of a combination electric motor, clutch and brake l4. Said electric motor, clutch and brake 14 may, for example, be a Singer Electric Transmitter series 552 or 553 produced by The Singer Manufacturing Company, Elizabethport F, New Jersey;

Said motor, clutch and brake l4 hereinafter referred to as a transmitter, is adjustably fastened to the bottom of bed H by any conventional means such as bolts or the like (not shown). A finger l2 fixedly mounted on said member 14 pivotally supports arm 11 and the other bent end of link 4 by means of a stub axle 12a.

Said transmitter 14 has a slideable drive shaft 14a extending therefrom through control yoke 13apivotally connected by pins 13 to arm 11. Axial movement of yoke 13a axially moves drive shaft 14a due to stops (not shown) on said drive shaft for engaging or disengaging said drive shaft through a mechanism (not shown) in transmitter 14 with the electric motor through the clutch or brake in transmitter 14.

A pulley I5 is fixedly connected to shaft as is a second pulley 16. Drive belt W extends around pulley 15 while drive belt 17 extends around pulley l5.

A plate 18 is fixedly connected to bed H and extends normal thereto. Said plate has a slot 19 through which is adjustably mounted the shaft 200 rotatably supporting a pulley 20 by means of a nut (not shown) on said pulley shaft on the opposite side of plate 18 to said pulley 16. Further pulleys-21 and 21a are rotatably mounted on plate 18.

Piston rod 23 of pneumatic cylinder 24 has screws 22 around which the ends of belt 17 are fastened while said belt extends around pulleys 20,21 and 21a. Cylinder 24 has

tubes

25 and 26 connected to the ends thereof for the operation of said piston rod.

Brake cylinder 9 has

tubes

26 and 27 connected to the ends thereof for the control of piston rod 8 while solenoid valve 10 has a tube 28 for the admission of air under pressure into the head of brake cylinder 9 as detennined by solenoid valve 10.

A pneumatic speed control 29 has an air line tube 30 connected to the bottom thereof while the top is connected to the bottom thereof while the top is connected to a presser foot lift cylinder 31 operating a piston rod 31a whose connection to presser foot U will be explained hereinafter.

An angle rod 32 has a knee plate 34A attached thereto by clamp 34. Said angle rod is pivotally connected by stub axle 33 to transmitter 14 and is also fixedly connected by welding or the like to cylinder 31 for raising the same.

A microswitch MS l is fixedly mounted on transmitter 14 with its control positioned for being pushed by link 4 when the same is raised. A second microswitch MS 2 is carried by link 4 and has its control positioned for being pushed against member 14 when link 4 is raised.

A make and break electrical switch 35 for the electrical circuit is housed in box 36 attached to bed H.

A bobbin winder is shown at 37 in FIG. 4 bearing against belt W.

A cylindrical housing 38 has an extension V of the sewing machine drive shaft rotatably extending through an axial bore of said housing, while cam 39 therein is fixedly connected to said extension V and thus to hand wheel V for rotation therewith. Said cam is circular except for radial point 40. A rocker 41 of electrical insulating material is pivotally mounted on pin 42 carried by housing 38 and carries a spring contact 44. A point 45 is fixedly mounted on housing 38 for normally being engaged by contact 44 due to spring 43 connected to housing 38 and rocker 41.

A second insulating rocker 46 is pivotally mounted on pin 47 carried by housing 38 and said rocker 46 is held against cam 39 by spring 48 attached to said rocker and housing 38. Said rocker carries a spring contact 49 normally bearing against point 50 fixedly connected to housing 38.

Points

45 and 50 are positioned 180 apart and so that cam 39 opens one

contact

44 or 49 from its

respective point

45 or 50 when the needle bar S is all the way up and the other of said contacts when the needle bar is all the way down. A cable 51 is connected to points 45 and 50.

Pulley 16 contains a slip clutch provided by hub 16a keyed by key 54 in slot 55 to shaft 14a and positioned within axial bore 52 of said pulley. A plurality of rollers 53 are positioned between hub 16a and said pulley 16 and hub 16a has a series of spaced apart radial teeth 56 and inwardly slanting curved peripheral portions 57 each extending between a pair of consecutive teeth 56 with a roller 53 positioned on each portion 57 for rolling movement between the pair of teeth 56 terminating said portion 57. A washer 58 is positioned against the outer end of said hub 16a and said pulley 16 while a ring nut 59 in threaded engagement with threads 60 on shaft 14a retains washer 58 in place. Hub 16a further has an annular flange 61 which provides a guide for the inner end of said pulley 16. Thus hub 16a, pulley 16, washer 58 and flange 61 provide a cage forrollers 53.

As best shown in FlGS. 2 and 5, the end face 62 of said sewing machine arm R has a recess 63 in which is mounted microswitch 64 alongside a pair of

microswitches

65 and 65a. Microswitch 64 has an extended control bar 66 spaced from extended control bars 67 and 67a of

microswitches

65 and 65a, respectively.

A block 68 is fastened to the end of a piston rod 81 by screws 69 and has a lateral finger 70 extending between control bar 66 and control bars 67 and 67a.

Sewing machine arm end 62 has recesses 71 in the back, 72 in the front and 73 in the bottom leading to recess 63 and a cover plate 74 in FIG. 4, for said arm end 62.

A U-shaped guide 75 is mounted on the front of arm end 62 while rollers 76, 77, and 78 extend across opening 72.

Pigtails

79 and 80 are connected to block 68 and positioned for extending through opening 72 between rollers 76, 77 and 78.

Said piston rod 81 extends through opening 71 into a pneumatic cylinder 82 fastened to the rear side of arm end 62 and which cylinder has a tube 82a connected to the inner end thereof, a screw 83 whose threads are in threaded engagement with cylinder 82 and lock nut 84b with screw 83 extending into cylinder 84 for limiting the movement of piston rod 81 towards the outer end of said cylinder. A coil spring 85 encircles piston rod 81 between block 68 and said cylinder.

A pin 86 attached to arm end 62 in opening 73 pivotally supports bent lever 87 extending through said opening 73. A sleeve 88 of a thread clamp is in threaded engagement with ann end 62 and has coil spring 89 on the inner end thereof while valve shaped stem 90 slideably extends through said sleeve 88 and coil spring 89 with its flanged inner end against arm 87 and retaining coil spring 89 against sleeve 88. Said sleeve has a valve seat shaped recess 91 in the outer end thereof for at times receiving the outer end of valve stem 90.

A thread guide 93 attached to arm R has bent spring arms 92 adjustably held by bolt 94 in threaded engagement with said arm R.

An automatic thread tension release consists of a cylinder 95, a piston 95a in said cylinder, a threaded rod 95b fixedly connected at one end to arm R, a disc 95c slideably mounted on rod 95b, a second disc 95d fixedly connected to arm R, tube 96 connected to the outer end of cylinder 95, nut 97 in threaded engagement with rod 95b and a coil spring 98 surrounding rod 95b between said nut and the intum end 95c of said cylinder 95. Rod 95b is split at its outer end of for receiving pin 95F extending through a slot in the extension of said piston and into cylinder 95 for preventing the turning of said cylinder.

A thread cutoff is best shown in FIGS. 5 and 10 to 12a, inclusive. Said thread cutoff has a pair of superposed

curved tubes

99 and 100 with a steel band 101 extending in tube 99 and a second steel band 102 extending in tube 100. Tube 99 has an upturned lip 103 at the free outer end thereof and an opening 104 extending therethrough above the free outer end of tube 100 and bobbin AA of the sewing machine 0. Said tube-free ends are positioned just below the needle opening for bed X of the sewing machine.

A cylinder head 105 is positioned below a bottom portion 106 of the sewing machine in threaded engagement with a cylinder tube 108. A cylinder cap 107 also is in threaded engagement with cylinder tube 108, but positioned above bottom portion 106 of the sewing machine and has

tubes

99 and 100 integral therewith and openings for

bands

101 and 102 which bands are also integral with piston rod 109, slideable in tube 108 and extending through head 105. A coil spring 110 surrounds piston rod 109 between head 105 and nut 111 in threaded engagement with said piston rod. A tube 112 is connected to and through head 105.

As shown in FlG. 10 the sewing machine bottom member 106 has a semicircular recess 116 while a block also has a semicircular recess 113 for holding tube 108 therebetween.

Bolts

115a and 115!) extend through block 115 and screw into bottom member 106 holding said block therein.

Microswitch 117, FIGS. 1 and 18, is mounted on standard leg LC with its control button 117a facing a knee plate 118 pivotally mounted on rod 119a pivotally connected by pivot 119 to bed H. Plate 118 has an arm 118a attached thereto while rod 119a has a pin 11% extending therefrom and collar 1190 with coil spring 119d whose ends engage said plate and collar.

Plate 118 as shown in FIG. 18 is pivoted inwardly depressing control button 117a and is held in that position by arm 118a engaging pin 11%. An operator by manually pushing said plate can disengage arm 118 from pin 11% whereupon plate 118 will pivot out and move upwardly through spring 119d releasing control button 1170. Thus plate 118 can be held against control button 117 a whenever the operator requires the same.

A double source of electrical current is indicated by double wall socket 120 with plugs .21 and 122 each plugged in one of the sockets. Plug 121 is connected to switch 35 while plug 122 is connected to the electric motor, clutch and brake 14 for energizing the same.

An air tube 123 is connected to a source of air under pressure 9 (not shown) and to and through box 124, FIG. 3, which houses solenoid valves A, B, C, D and 140 and

air speed regulators

125, 126 and 127 and tube 128, FIG. 14, connected to said tube 123.

Referring to FIG. showing the back of sewing machine Q, piston rod 310, see FIG. 3, extends through bed H and is loosely connected to lever 129 pivoted on arm R by a pin 130. A pair of nuts 131 in threaded engagement with threads 132 of rod 314 are on each side of lever 129. Said lever 129 is pivotally connected by pin 133 to link 134 while link 134 is pivotally connected by pin 135 to the conventional presser foot raising and lowering lever 136 o of the sewing machine.

Mounted on the top of the sewing machine 0, adjacent to the handwheel V is a bracket 137, having a downwardly extending leg 138. Secured to said leg 138, is an air cylinder 139 having a piston rod 141 extending therefrom in the direction of the handwheel V. A pin 142 pivotally supports arm 143 on said bracket so that arm. 143 extends between leg 138 and handwheel V. The free end of arm 143 has a roller 144 rotatablymounted thereon which is adapted to move into notch 145 on the handwheel V when said piston rod 141 is extended due to air being forced into cylinder 139 through tube 166 which is connected to control valve 140. The notch 145 is located in such a position on handwheel V so that the needle bar 8 of the sewing machine will be in top dead center position when said roller 144 is engaged in notch 145.

Referring to FIG. 7a, notch 145 is in the periphery of a ring 146 held by set screws 147 on handwheel V modified to receive the same. Housing 38 has an extension 148. integral therewith and link 149 attached to said extension. One end of spring 150 is attached to link 149 andits other end to arm'152 while stop 151 extends from extension l48'to arm 152 limiting the contraction of spring 150.

Screws 153 extend through openings l54in bracket 137 into the top of said sewing machine for retaining said bracket thereon. Screw 155 extends through washer 156 and spring 157 into threaded opening 155a in said bracket.

The threaded end of cylinder139 has nut 158 and washer 159 thereon and extends into threaded opening 160 in said bracket for being supported thereby.

Set screw 161 is in threaded opening ,162;for engaging the end of pin 142'in opening 174 for retainingsaid pin therein.

Elbow 163 is in threaded engagement with threaded opening 164 in cylinder 139 while eyelet 165a and sleeve 165 are in said elbow and nut 1640 is in threaded engagement with'said elbow retaining tube 166 to said elbow.

Clamp 167 for wire 51 and arm 152 are attachedto bracket leg 138 by screws 168 passing through openings 169 in arm 152 into threaded openings 169a inleg 138. Clamp 170 for wire 51 has screw 171 extending through'washer 172, clamp 170 and into threaded opening 172a in arm 152.

Arm 143 has a lateral opening1173 through which extends pin 142 and a roller pin 175 extending through arm openings 176 and roller 144 rotatably retaining said roller partially in.

arm recess 174. A retaining ring 177 fits the end of roller pin 175 for holding the same in place.

FIG. 14 is a combination electrical and pneumatic sche matic diagram showing the electrical as well as compressed air connections between the elements hereinbefore referred to. In

this diagram there is also included relays R and R whose.

operation will be hereinafter described.-

FIG. 16 is a view of the electrical circuit wiring diagram of FIG. 14 when needle T is in its up position and presser foot U raised, but with synchronizer valve 140 omitted. When the operator releases his heeling action on treadle F, the presser foot U will drop.

FIG. 17 is a view of the electrical circuit wiring diagram of FIG. 14 when needle -T is in its down position;

In the operation of a sewing machine Q, modified according to the present invention, thread M is passed to post P, through guide Y, between disc 95!: and disc 95d, through thread tension lever Z, through eye 75andpigtails 80, between valve stem and seat 91, through the eye of needle T and double looped through bed X and opening 104in tube 99. The thread from bobbinAA also passes through opening 104 in tube 99 and bed X so that the end of thread M and the bobbin thread are above bed X.

If the operator presses forward on the treadle F, the sewing machine will be operated in the nonnal manner. That is, pressing hard forwardly and down on said treadle causes the sewing machine to run at top speed while letting up on said treadle causes the sewing machine to slow down and taking the foot off the treadle completely stops the sewing machine stopping the sewing action.

When the operator feeds the work piece across bed X beneath needle T and presser foot U and heels down on treadle F raising link 1 pressing link 4 against microswitches MS 01 and MS 2,- FIG. 3, tripping said microswitches, microswitch MS 01 supplies current to points 45 and 50. Cam 40 rotates at the down position of needle T. By energizing point 45 and' contact 44, the sewing machine will stop with needle T all the wayup while. energizing point 50 and contact 49, the sewing machine will stop with needle T all the way down.. Thus if point 45 and contact 44 are energized, the sewing machine can be made to stop withneedle T up, since cam 40 willopen contact 44 from point 45 when said cam rotates around to that position breaking the electrical circuit.

If contact 49 engages point 50 they 1 supply current to the solenoid valves D and 10 and relay R,. Said solenoid valves D and 10 pass compressed air to the positioning cylinder 24 by tube 25 and the brake-cylinder 9 by tube 9a extending piston rod 23 which pulls cable 17 rotating pulley 16 in a direction which moves rollers 53' against teeth 56 of the slip clutch of FIGS. 8 and 9 against pulley 16 causing said clutch to grab and thus rotate shaft 140 rotating in transmitter 14 and also pulley 15, belt W and hand wheel- V causing cam 40 to rotate until it opens contact 49 from point-50. At the-same time the needle positioner, solenoid valves andrelay R are deenergized shifting piston rod 23 into cylinder 24 andputting brake cylinder 9 in its brake position stoppinghand wheel V, opening the

contacts

44 and 49, thus the-brake of transmitter 14 is released and reappliedsvery quickly while contact 49 and point'50 are open. Needle vT is thus now positioned all the way down through the work piece. Also at the same time when relay R was deenergized the normally closed contacts in said relay supplied current to solenoid Tvalve C passing air to cylinder 31 lifting presser-foot S through rod 31a, lever 129,

links

134 and 135 of FIG. 15, which allows the operator to tumthe work piece around the needle. Piston -rod 23 returnsinto cylinder 24through the slip action of the clutch in pulley 16.

Said slip clutch of' pulley 16is necessary to prevent the.

same and energizing contact 44 and point 45, solenoid valvesv D and 10 and relay R thus the brake of transmitter 14 is released and piston rod 23 pulls pulley 15 and the slip clutch of pulley 15 around so-that needle T is moved up. The brake of transmitter 14 is thenquicklyreapplied and solenoid valves A and 'B actuated releasing disc c from disc 95d releasing thread M, moving

pigtails

79 and 80 to the left of FIG. Sdrawing thread M in recess-63, raising piston rodl09 so that band 102 gives thread M and the bobbin thread a U-shaped bend as shown in FIG. 5 and then band 101 severs the threads from the work piece automatically. With microswitch 117 set in the needle up position, current is sent directly to valve l40which will open allowing air to pass'through tube 166-to cylinder 139;"As the handwheel U is rotated by the positioning cylinder 24, roller 144 will ride on ring 146 until it engages notch 145 at which time the needle T will be in top dead center position in which position the normal thread tensions of the sewing machine are released to allow the thread M to be drawn freely from the supply by the thread puller. Presser foot U remains in its up position until the operator lets up on his heel on treadle F, at which time said presser foot drops. When piston rod 81 goes into cylinder 82 as far as allowed by screw 83, finger 70 activates microswitch 64 which energizes relay R breaking the return line of the synchronizer solenoid 140 to return it to its normal position. Relay R is locked in the down position by current from microswitch MS 02 and starts the return of piston rod 81 to its position in FIG. 5 and at the same time activates piston rod 109 and

bands

101 and 102. When piston rod 81 reaches its position of FIG. 5 it operates

microswitches

65 and 65a, and piston rod 109 is lowered. Releasing microswitch 117, the foot lift solenoid valve C is energized lifting presser foot U.

With the operator still pressing down with his heel on treadle F and holding microswitch 117 closed and then releasing said microswitch 117 before cam 40 reaches and opens contact 44, piston rod 23 will turn transmitter shaft 14a and pulley 15 around to the down position of needle T before said needle stops and presser foot U is raised. This puts one stitch in the work piece at a time. Such operation required requires a quick tap on knee plate 118 with the operators knee, while to cut the thread from the work piece as hereinbefore described requires microswitch 117 to be held closed somewhat longer.

For greater speed in cutting the thread M from the work piece knee plate 118 can be locked against microswitch 117 by pushing said knee plate all the way down, see FIG. 18, rotating said knee plate against control button 117a and raising said knee plate so that the hook on arm 118a engages pin 11%. Then the operator can at any time heel backward on treadle F which activates piston rod 109 and thus

bands

101 and 102, positioning the needle up, releases the tension on the thread, pulls the thread, trims the work piece and raises the presser foot. As long as the treadle is heeled, the presser foot remains up permitting the removal of the finished work piece and the introduction of a new work piece. However, said microswitch must be released and opened by manually moving arm 1180 from pin 11% and said knee plate from control button 1170 before the needle T down positioning elements as hereinbefore described can be operated.

When the operator presses forwardly or toes down hard on treadle F the sewing machine Q operates in the normal manner at top speed. Letting up on treadle F causes the sewing machine to slow down and taking the foot off of the treadle F completely stops the sewing machine.

Lever 87 is positioned between valve stem 90 and block 68 so that movement of said block to the entire right of FIG. 5 pushes said valve stem to the right against spring 89 releasing the thread M. However, when block 68 is to the left of FIG. 5, spring 89 returns said valve stem against seat 91 against thread M. At any time the operator can manually pivot lever 87 to move either valve stem 90 or block 68 if desired.

Solenoid valves A, B, C, D and 10 are conventional electrically operated valves such as manufactured by the Automatic Switch Co., Florham Park, New Jersey, Catalog Nos. GY8314A33 and GY8314A51. Similarly

regulators

125, 126, 29, 24a and 127 are conventional air flow control valves.

The present invention is capable of considerable modifica tion and such changes thereto as come within the scope of the appended claims is deemed a part thereof.

We claim:

1. In a sewing machine, a thread tensioning and releasing means comprising a pneumatic cylinder having an air inlet tube at one end, a piston rod slideably extending from said cylinder and fixedly connected to said sewing machine, a flat member fixedly mounted on said sewing machine, a second flat member carried by said cylinder facing said first flat member, resilient means tending to retain said flat members together with a sewing machine thread therebetween, pneumatic means for pulling the thread, and means for operating said cylinder moving said second flat member away the first flat member and operating said pneumatic means pulling said thread.

2. In a sewing machine, a thread tensioning and releasing means comprising a pair of opposed flat members for retaining a sewing machine thread therebetween, means for at times separating said flat members, a pneumatic cylinder fixedly connected to said sewing machine, a piston rod slideably extending from said cylinder, pigtails carried by said piston rod for receiving a thread therebetween, means for at times operating said first means and passing compressed air to said cylinder drawing said piston rod therein and resilient means tending to move said piston rod from said cylinder.

3. In a sewing machine as claimed in claim 2, a tubular plug connected to said sewing machine having a valve seat, a valve stem slideably mounted in said plug with a head facing said seat, resilient means tending to hold said head against said seat with the sewing machine thread therebetween and a lever pivotally mounted on said sewing machine and positioned for at times being pivoted by said piston rod and pushing said valve stem against said resilient means and thus said head from said seat.