US2760458A

US2760458A - Sewing machine

Info

Publication number: US2760458A
Application number: US384735A
Authority: US
Inventors: Waldemar A Ayres
Original assignee: White Sewing Machine Corp
Current assignee: White Sewing Machine Corp
Priority date: 1953-10-07
Filing date: 1953-10-07
Publication date: 1956-08-28
Anticipated expiration: 1973-08-28

Description

W. A. AYRES SEWING MACHINE Aug. 28, 1956 2 Sheets-Sheet 1 Filed Oct. 7, 1953 add 5 4 e w A m m w M Aug. 28, 1956 w. A. AYRES 2,760,458

SEWING MACHINE Filed Oct. 7, 1953 2 SheetsSheet 2 INVENTOR. Mwsmw A. Ayess BY (lg,

A TTONE Y5 United States Patent SEWING MACHINE Waldemar A. Ayres, Lakewood, Ohio, assignor to White Sewing Machine Corporation, Cleveland, Ohio, a corporation of Ohio Application October 7, 1953, Serial No. 384,735

19 Claims. (Cl. 112-454) This invention relates to an upper thread tension device for a sewing machine.

It is customary in sewing machine to provide on the front side of the sewing machine head a tensioning device for the upper thread. Also it is usual to provide on the front of the sewing machine head, in addition to the upper tension device, a check spring or auxiliary take-up spring for the purpose of taking up the slack in the upper thread when the needle is out of the cloth in order to obviate danger of the thread forming a loop around the needle tip which might result in the thread breaking during the latter part of the sewing cycle when the thread take-up pulls in the slack.

The upper thread tension devices in the majority of cases consist of two motionless disks between which the upper thread passes. In combination with such disks usually there is provided adjustable spring means for varying the pressure With which the disks are pressed together and thus vary the frictional drag exerted upon the upper thread passing between the disks. This type of upper thread tension device has certain disadvantages since any nonuniformity of the thread, such as lumps or thicker thread portions, will produce nonuniform tension on the thread with a resultant uneven and inferior quality in the sewing produced by the sewing machine. Also with this type of upper thread tension device threads of different size and of different coefiicients of friction as, for instance, cotton or silk thread, will require changes of adjustment of the tension devices for different sizes and kinds of threads.

Another type of upper thread tension device which has been used, in addition to the first mentioned type, is that wherein the upper thread rotates a disk or pulley around which the thread is wrapped and an adjustable frictional drag is provided between the disk and the sewing machine head.

Regardless of the type of upper thread tension device device and before it passes through the eye of the needle.

Frequently the operator of a sewing machine improperly threads the check spring or auxiliary take-up spring evice and the operation of the sewing machine is disturbed to such an extent that frequently it is necessary to have a service man called to correct it.

An object of the present invention is to provide an improved and novel upper thread tension device for a sewing machine and which device embodies therein elements that automatically take up the slack of the upper thread when the needle is out of the cloth, thereby eliminating the necessity of providing, in addition, a separate check spring or auxiliary take-up spring device.

A further object is to provide an upper thread tension device for a sewing machine, as referred to in the previous object, and wherein provision is made for easily and accurately adjusting the device to provide the desired thread tension.

Further and additional objects and advantages not here-' inbefore specified will become apparent hereinafter during the detailed description which is to follow of several embodiments of the invention and which embodments arev illustrated in the accompanyingdrawingsforming a part I of this specification and wherein,

Fig. 1 is a sectional view through a portion of a sewinachine head and through an upper thread tension device secured to said head and embodying the present invention and is taken on line 1-1 of Fig. 2 looking in the direction of the arrows.

Fig. 2 is a partial elevational and partial sectional View taken substantially on irregular line 22 of Fig. 1 looking toward the front of the sewing machine head as indicated by the arrows.

Fig. 3 is a artial elevational and partial sectional view taken substantially on line 33 of Fig. 1 looking toward the front of the sewing machine head as indicated by the arrows.

Fig. 4 is a view similar to Fig. 1 but showing a modified form of upper thread tension device embodying the invention.

Pg. 5 is a detail sectional view taken substantially on line 55 of Fig. 4 looking in the direction of the arrows, and

Fig. 6 is a View similar to Figs. 1 and 4 but illustrating a further embodiment of the invention.

A portion of a sewing machine head is indicated in the drawings at 15. This portion of the sewing machine head is at the front sde of the head i. e., the side toward the operator and is located adjacent to the end of the head wherein the reciprocating needle bar and the presser foot are mounted as will be well understood in the art.

The upper thread tension device of Figs. 1 to 3 inclusive will now be described. The wall of the sewing machine head 15 is provided with a threaded opening into which opening is screwed the externally threaded end 16 of a mounting sleeve 1'7 and said sleeve extends outwardly from the front side of the head. The outer end 18 of the sleeve is provided with a pair of diametrically located radially extending slots 19 for a purpose later to be explained. The sleeve 17 intermediate the externally threaded portion 16 and the outer end 18 thereof has a smooth external cylindrical portion 20 on which is rotatably mounted the hub 21 of a friction disk 22. The hub 21 and friction disk 22 while rotatably supported by the portion 20 of the sleeve 17 also have limited axial movement on said portion so that the disk 22 can be contacted with a friction pad 23 of any suitable friction material such that will create a frictional drag acting against the rotation of the disk 22. The friction pad is secured to a mounting plate 24 that is secured to the front of the sewing machine head 15 and which mounting plate is of circular configuration and is provided on its circumference with an outwardly extending annular head 25 Within which the friction pad 23 and friction disk 22 are located.

The friction disk 22 inwardly of its circumference is provded wth an annular flange 26 that s concentric to the hub 21. The flange 26 is provided with an arcuate slot passing dirough the slot 27. The screw 29 is also connected to one end of a spiral spring 33 located in the annular chamber defined by the hub 21 and the annular flange 26 and having its opposite end attached by a screw 31 to the hub 23.

It will be seen that the ring or pulley, 28 will have limited rotation relative to the flange 26 and friction disk 22 within the limits of the slot 27 through which the screw 29 projects. it will also be seen that such relative rotation of the ring or. pulley 28 in one direction will wind up the a spiral spring 30 and unless restrained the wound-up spiral spring 34) will function to relatively rotate the ring or pulley 23 in the opposite direction. The purpose of this arrangement will become apparent hereinafter.

A, cover plate 32 is mounted on the hub 21 of the friction disk 22 and encloses the thread ring or pulley 23 annular flange 26 and spiral spring 38; said hub 21 extending outwardly beyond theclosure plate 32 and overlying the outer end 18 of the sleeve 17 and a small portion of the slots 19 therein.

A small washer or thrust member 33 ismounted-on the end portion 13 of the sleeve 17 and bears against the extended end of the hub 21 and has on its inner circumference diametrically aligned radially inwardly extending lugs 34 which project into the slots 19 of the outer end 18 of the sleeve 26. The small washer 33 on its outer circumference is provided with an. arcuate cut-out forming stop shoulders 35 spaced apart a suitable distance as, for instance, 120 and for a purpose later to be pointed out. a

A shaft 36 extends through the sleeve 17 and is capable of axial movement in the sleeve but is not rotatable therein. The inner or left hand end of the shaft 36 is provided with a threaded portion 37 and beyond that portion with a tip 38 for a purpose later to be explained. A nut 39 is mounted on' the threaded portion 37 of the shaft 36 and said nut supports at one end a leaf spring 4%, the opposite end of which is connected to an anchoring screw 41 extending through the head 15. The spring 46 intermediate its ends is provided with a bowed portion 32 which contacts the head 15, wherefore said spring normally urges and the annular bead of the mounting plate 24 for the upper thread to pass or pulley 28. I

The friction adjusting knob 44 at the bottom of the cupshapedportion thereof is provided with a raised annular rib 45 that bears against the Washer. 33 which, as previously stated, bears against the extended end of the hub 21 of the friction disk 22. it will be seen that by rotating the knob i4v in one or the other direction the pressure extherethrough and around the ring ,erted'by the washer 33 on the end of the hub 21 can be varied and consequently the pressure between the friction disk 22 and the friction pad 23 can be varied.

The knob'44 carries a stop screw 46 which has its inner reduced portion located between the stop shoulders on the washer 33, wherefore said stop pin will engage one or the other of said stop shoulders to limit the amplitude of rotation of the knob in either direction.

As'already stated, the spring 4% functions to normally urge the, shaft 36 toward the left as viewed in Fig. l,

with the result that the annular rib 45 of the knob 44 presses on the washer 33 to force the friction disk 22 into contact with the friction pad 23 with a predetermined spring load.

9 There are occasions when it is desirable to release the upper thread tension and a linearly movable lever arm 47 is provided for this purpose. The lever arm 47 slides in a supporting bracket is-secured to the inside of the head 15 and said lever arm at its upper end has a reduced portion 47:: and an inclined or camming portion 47b.

. It will be seen that when the lever armdi is raised the camming portion 47b there0f engages the tip 33 of the shaft 36 and moves said shaft toward the right against the action of the spring i0. This movement ofthe shaft 36 moves the knob 44 and releases the pressure of the rib 45 on the Washer 33 and also the pressure of the fric-' tion disk 22 on the friction pad 23. The lever arm 47 4 may be part of or operatively connected with the mechanism for raising the presser foot as will be well understood and it will also be appreciated that the thread tension device is released usually at a time when the pressure foot is raised.

The upper thread is passed between the bead 25 of the mounting plate 24 and the friction adjusting knob 44 and is given a complete turn around the thread receiving ring or pulley 28 from whence it extends to the needle where it is threaded through the eye of the latter. The knob 44 is turned in the proper direction to screw it toward or away from the washer 33 in order to provide the desired pressure between the friction disk 22 and the friction pad 23.

It will be recalled that the adjustment of the knob 44 is a limited adjustment as defined by the stop shoulders 35 and, if desired, the knob 44 can be provided with suitable indicia calibrated in terms of adjustment so the operator can visually determine if he has given the knob the desired adjustment.

When the sewing machine is operated the pull of the upper thread that is wound around the thread receiving ring or pulley first rotates such ring or pulley relative to and on the annular flange 26 of the friction disk 22 until the screw 29 engages the end of the slot 27 in the flange 26. This rotation of the thread ring or pulley 28 Winds up the spring 30, The continued pull of the upper thread on the ring or pulley 28 after thescrew 29'has engaged the end of the slot 27 causes the ring or pulley and the friction disk 22 torotate as a unit and such rotation is resisted by the frictional drag between the disk 22 and the friction pad 23 and this puts the desired tension on the upper thread. If slack occurs in the upper thread between the ring or pulley 28 and the needle, as -frequently occurs when the needle is out of work, the woundup spring 36 comes into action to rotate the ring or pulley 28 in the-reverse direction and relative to the annular flange 26, thus automatically taking up the slack in the thread. Consequently likelihood of the thread looping around the, needle or the needleabar orany other part and thereafter interfering with the proper operation of the machine, or breaking, is'fully eliminated and no separate check spring" or auxiliary take-up spring is required.

Also the necessity of passing' the upper threadproperly through. such .check spring .or

the friction disk 22 is not pressed against the friction pad 23. Of course as soon as the lever 47 is lowered the leaf spring .40 moves the shaft 36 toward the left and brings the annular rib .45 of the knob 44 into springtensioned engagement with the washer'33, whereupon the friction disk 22 is again held against the friction pad 23 under a spring load. Also if substantially no tension is desired for the upper thread the knob Mean .be turned to its'minimum adjusted position.

It will be seen that the upper thread tension device just described is efficient in operation and embodies in it elements that eliminate the necessity of the separate check spring or auxiliary take-up spring. Also it will have been seenthat the upper thread tension device is not affected in its function by upper threads of different size, of different materials, or which have nonuniformity in crosssect ional"size, such as might be produced by lumps or thicker thread portions. 7 i In Figs; 4 and 5 a modified form of ,upper thread tension device embodying the invention is illustrated. In this form of the invention a mounting sleeve 49 similar It .will be recalled that such movement of the shaft 36 moves the knob 54 and .disengages the annular rib 45 of the knob from its contract with the washer or thrust member 3.3, wherefore wise movement thereon.

'to the mounting sleeve 17 of the previously described form has one threaded end 50 screwed into a threaded opening in the sewing machine head 15 as in the previously described form. The opposite extended or outer end of the mounting sleeve 49 also is externally threaded as indicated at 51 and is provided with diametrically opposed elongated slots 52 for a purpose later to be explained.

The mounting sleeve 50 intermediate its ends is provided with a smooth external cylindrical portion 53. The form of the device shown in Figs. 4 and 5 embodies many parts which are identical or substantially identical with the corresponding parts of the first described form and therefore such parts will be given the same reference characters as were used in the first described form. These parts which are the same as in the first described form comprise the mounting plate 24 with its bead 25, the friction pad 23, the friction disk 22 with its annular .fiange 26 and hub 21 that rotates on the smooth portion 53 of the mounting sleeve 49 and has limited end- Also the construction shown in Figs. 4 and 5 includes the thread receiving ring or pulley 28 of the first described form, the spiral spring 30, screws 29 and 31 and cover plate 32 previously described and functioning in exactly the same way as .to the corresponding parts in the first described form.

The device of Figs. 4 and 5 includes a ring washer or thrust member 54- that is mounted on the mounting sleeve 49 adjacent the free end of the hub 21 of the friction disk 22 and adapted to be held in engagement with said through the slots 52 in the mounting sleeve the washer can have endwise movement on the mounting sleeve relative thereto and relative to the free end of the hub 21. A nut 56 is screwed on the threaded end 51 of the mounting sleeve and said nut is provided at its inner end with an annular flange 57. A spring washer 58 is interposed between the inner end of the nut 56 and the ring washer S4 and functions to urge the ring Washer or thrust member into contact with the end of the hub 21 with a spring load and to produce a resultant urging of the hub 21 and the friction disk 22 toward the friction pad 23 to frictionally engage the disk with said pad as will be well understood.

It will also be understood that rotation of the nut 56 in one or the other direction will effect an adjustment in the spring load exerted by the spring washer 58 on the ring washer 54. The flange 57 of the nut 56 may carry a stop pin 59 which extends a sufiicient distance so that the opposite ends of thepin 55 will lie in its path during rotation of the nut 56. In other words, the nut 56 can be rotatably adjusted in one or the other direction through an arc of approximately 180.

In order to facilitate the adjustive rotation of the nut 56 said nut is externally threaded so that an operating knob 69 can be screwed thereon and locked in place by means of lock screws 61 passing through the knob and screwed into tapped sockets in the nut.

Also. screwed on the nut 56 and clamped thereon between the flange 5'7 and the operating knob 60 is a dial closure plate 62 which encloses the ring washer or thrust member 54 and spring washer 5S and is provided with an annular head 63 that surrounds the circumference of the closure plate 32 and a portion of the thread ring or pulley 28 but is spaced from the head 25 of the mounting plate 24 so that the upper thread can be wound on the ring or pulley.

58 to the ring washer or thrust member 54 and also 6 correlated to the degree of frictional drag between the friction disk 22 and the friction pad 23.

A plunger 64 is mounted in the mounting sleeve 49 and is movable endwise therein. The plunger 64 extends within the head 15 of the sewing machine and its inner end is rounded as indicated at 65. The opposite end of theplunger is adapted to contact the pin 55. A linearly movable lever arm 66 similar to the lever arm 47 previously described in connection with the form shown in Figs. 1 to 3 inclusive is provided and has a reduced upper end 67 which normally contacts the rounded end 65. of the plunger'64.

The lever arm 66 just below its reduced upper end 67 is provided with an inclined or camming portion 68 and it will be seen that if the lever is raised such camming portion 68 will react against the rounded end 65 of the plunger 64 to move said plunger toward the right and to bring its opposite end into engagement with the pin 55 and then move the ring washer or thrust member 54 axially of the mounting sleeve 49 to compress the spring washer 58 and remove the pressure of the ring washer 54 from the hub 21 to thus relieve frictional contact between the friction disk 22 and the friction pad 23. This occurs when it is desired to release the tension on the upper thread as, for instance, if the presser foot is raised, and it will be understood that the lever arm 66 can be connected with or operatively associated with the mechanism for so raising the presser foot. When the lever arm 66 is lowered the spring washer 58 moves the ling washer 54 back into engagement with the free end of the hub 21 to reestablish the frictional contact between the friction disk 22 and the friction pad 23. Such movement of the ring washer 54 causes the pin 55 to move the plunger 64 toward the left and into engagement with the reduced upper end 67 of the lever arm 66.

Inasmuch as the operation of the form of the device shown in Figs. 4 and 5 is the same as the operation of the form shown in Figs. 1 to 3, it is not necessary to set forth herein a statement of the operation of this modified form embodying the invention.

In Fig. 6 there is shown a still different form of upper thread tension device embodying the present invention. In the form of device shown in Fig. 6 the mounting plate 24, friction pad 23, friction disk 22 with its hub 21 and annular flange 26 are the same as in the preceding forms and need not be redescribed. Also the thread receiving pulley or ring 28, spiral spring 30, screws 29 and 31 and cover plate 32 correspond to the same parts in the preceding forms and need not be described.

In the form shown in Fig. 6 the hub 21 of the friction disk 22 is rotatable on a shaft 69 that extends through the head 15 and is supported in the head for endwise movement. The shaft 69 is provided with a circular flange 70 located in a counterbore 71 in the head 15 and preferably acting to assist in guiding the endwise movement on the shaft. A coil spring 72 surrounds the shaft 69 and has one end abutting the flange 70 and its opposite end the mounting plate 24 and said spring normally urges the shaft toward the left viewed in Fig. 6.

A thrust washer or member 73 is located on the shaft 69 adjacent the free end of the hub 21 of the friction disk and said washer carries a pin 74 which extends through an elongated axial slot 75 formed in the outer end of the shaft 69 with said pin 74 holding the washer 73 and shaft 69 against relative rotation, but allowing axial movement of the washer relative to the shaft.

An adjusting knob 76 comparable to the knob 44 of the first described form and to the knob 60 and dial closure plate 62 of the second described form screws on the threaded outer end of the shaft 69 and is provided with a counterbore in which the thrust washer or member 73 is located.. It will be understood that the knob 76 can be turned in one or the other direction to vary the thrust of the washer 73 of the hub 21 and thus vary the pressure of the friction disk 22 against the friction 7. pad 23, it being recalled that the spring 72 normally exerts a spring load on these parts through the shaft 69, knob 76 and washer 73.

A slidable thread tension releasing rod 77 is supported by a suitable supporting bracket in the head 15 and said rod is provided with a cut-out camming portion 78 that normally extends through an opening '79 in the shaft 69 and which opening is provided with beveled surfaces. 7 It will be seen that as the rod 77 is moved endwise from the position shown in Fig. 6 the shaft 69 will be moved toward the right to compress the spring 72 and relieve the thrust of thethrust washer 73 on the hub 21 and thus release the frictional contact-between the friction disk 22 and the friction pad 23. The movement of the shaft 69 toward the right as just referred to of course releases the upper thread tension.

The rod 77' may be actuated by any suitable means as, for instance, an actuating lever 89 that is operatively connected to the rod as will be well understood in the art. The device shown in Fig. 6 operates in the same manner as do the previously described devices and hence it is not believed necessary to set forth herein any statement of the operation of this form of the device.

Although preferred embodiments of the device have been illustrated and described herein, it will be understood that the device is susceptible of various modificahens and adaptations within the scope of the appended claims.

- Having thus described my invention, I claim:

1. An upper thread tension device for a sewing machine comprising, in combination with the sewing machine head, means supported by the head and extending outwardly thereof, a member rotatable on said means and movable endwise relative thereto and including a planular circular disk surface portion perpendicular to the longitudinal center line of said means, a friction pad supported by said head-and engageable by said surface portion, a thread receiving ring or pulley carried concentrically by said rotatable member inwardly of the circumference of said disk surface portion and having limited rotation independently of and relatively to said member, spring means carried by said member and operatively associated with said member and said ring or pulley and tensioned by the independent relative rotation of the pulley or ring in one direction and then acting to rotate the pulley or ring independently of and relatively to said member inthe opposite direcetion, and

means supported by the first named means for maintaining said surface portion of said' member in engagement with said friction pad.

2. An upper thread tension device as defined in claim 1 and wherein said means that is supported by' the head and extends outwardly thereof nonrotatably mounts a thrust member engageable with said rotatable member to impart thrust thereto axially of said means to engage the "planular surface portion with said friction pad, and a friction adjusting member adjustably carried by said means and operatively associated with said thrust member to adjustably move the'latter axially of said means to vary the frictional pressure between said'planular surface portion of said rotatable member and said friction pad.

'3. Anupper thread tension device as defined in claim 2 and wherein means isprovided for moving said thrust member away from engagement with said rotatable member to relieve the frictional engagement of the planular surface portion of the rotatable member with said frica Pad- An u e hr d n ion de ic s efi ed in slaim 2 and wherein means is provided for imparting a spring tensioned load on said thrust member in a direction toward said rotatable member.

5; An upper thread tension device as defined in claim 4 and wherein means is provided for selectively reliev ing said thrust member of said spring tensioned load.

A upp r hre d. t n i n d vic for a s ing nachine comprising, in combination with the sewing ma-v chine head, means supported by the head and extending outwardly thereof, a member rotatable on said means and movable endwise relative thereto and including'a planular surface circular disk portion, a friction pad supported by said head and engageable by said surface por, tion, a threadreceiving ring or pulley carried concentrically by said rotatable member inwardly of the circumferenee of said disk surface portion and having limited rotation independently of and relatively to said member, spring means carried by said member and operatively associated with said member and ring or pulley and tensioned by the independent relative rotation of the pulley or ring inone direction and then acting to rotate the latter independently of the member in the opposite direction, a thrust member nonrotatably mounted on said supporting means but movable endwise thereof to engage said rotatable member and maintain the planular surface portion thereof in frictional contact with said friction pad, and spring tensioned means for exerting a spring load on said thrust member acting in a direction to move said thrust member into engagement with said rotatable member and including a rod slidable endwise in said supporting means, and means for moving said rod endwise in one direction to relieve the spring tensioned load on said thrust member.

7. An upper thread tension device as defined in claim 6 and wherein adjustable means is provided for varying the action of the thrust member on said rotatable member to vary the frictional engagement of the planular surface portion of the rotatable member with said friction pad.

8. An upper thread tension device for a sewing machine comprising in combination with the sewing machine head, a tubular means supported by the head and extending outwardly thereof, a member rotatable on said means and movable endwise relative thereto and including a planular friction disk surface portion, a friction pad supported by said head and engageable bysaid surface portion, a thread receiving ring or pulley carried by said rotatable member and having limited rotation ind pendently of and relatively to said member, spring means operatively associated with said member and said ring or pulley and tensioned by the independent relative rotatron of the r ng or pulley in one direction and then acting to rotate the latter independently of the member in the opposite direction, a thrust member nonrotatably carried by said tubular means'and having movement'relative to said tubular means axially thereof and engageable with said rotatable member, a rod or shaft extending through said tubular means and outwardly of the opposite ends thereof with the end of said rod or shaft beyond said thrust member being threaded, an adjusting knob screwed on said threaded end of said rod or shaft and engaging said thrust member, spring means acting on said rod or shaft at the opposite end thereof and normally urging said rod or shaft in a direction to maintain said thrust member in engagement with said rotatable member with a spring load, and means acting on said opposite end of said rod or shaft for selectively moving it in a direction opposite to'its direction of movement under the action of said last named spring means.

9. An upper thread tension device as defined in claim 8 and wherein said thrust member is provided with arcuately spaced stop shoulders while said adjusting knob carries a stop element extending intermediate said stop shoulders wherefore rotative adjustment of said knob is within predetermined limits.

10, An upper thread tension device as defined in claim a 8 and wherein said tubular means is provided with dia- -r n etrical ly aligned axially extending slots while said thrust annular flange while said upper thread receiving ring or pulley is rotatably supported on said flange, said flange being provided with an arcuate slot of predetermined length while said first mentioned spring means is operan'vely connected to said ring or pulley by a connecting element extending through said slot wherefore independent relative rotation of said ring or pulley in opposite directions is within predetermined 12. An upper thread tension device for a sewing machine comprising, in combination with the sewing machine head, tubular means supported by the head and extending outwardly thereof and having its outwardly extending end externally threaded and provided with diametrically aligned longitudinally extending slots, a member rotatable on said means and movable endwise relative thereto and including a friction disk planular surface portion, a friction pad supported by said head and engageable by said portion, a thread receiving ring or pulley carried by said rotatable member and having limited rotation independently of and relative to said member, spring means operatively associated with said member and said ring or pulley and tensioned by the independent relative rotation of the ring or pulley in one direction and then acting to rotate the latter independently of the member in the opposite direction, a thrust member mounted on said tubular means and carrying a diametrically extending pin passing through said slots and said tubular means, an internally threaded adjusting member mounted on said threaded end of said tubular means, spring means interposed between said adjusting member and said thrust member and acting to urge said thrust member into engagement with said rotatable member to maintain interengagement between the planular surface portion of the rotatable member and the friction pad, a plunger slidable in said tubular means and having one end engaging said pin while its opposite end extends beyond said tubular means, and cam means acting on said opposite end of said plunger for moving the same in a direction to overcome the action of the spring means that is interposed between the adjusting member and the thrust member and to move said thrust member in a direction to relieve the frictional engagement between said friction pad and the planular surface portion of the rotatable member.

13. An upper thread tension device as defined in claim 12 and wherein said pin has its opposite ends extending beyond the periphery of said thrust member while said adjusting member mounts a stop element engageable with the ends of said pin to limit adjusting rotation of said adjusting member.

14. An upper thread tension device for a sewing machine comprising, in combination with the sewing machine head, means slidably supported by the head and extending outwardly thereof, a spring carried by said means and acting to urge the same in a direction inwardly of the head, a member rotatable on said means and movable endwise relative thereto and including a friction disk planular surface portion, a friction pad supported by said head and engageable by said portion, a thread receiving ring or pulley carried by said rotatable member and having limited rotation independently of and relatively to said member, spring means operatively associated with said member and ring or pulley and tensioned by the independent relative rotation of the ring or pulley in one direction and then acting to rotate the latter independently of the rotatable member in the opposite direction, a thrust member nonrotatably carried by the outwardly projecting end of said first named means and having relative movement longitudinally of said means, the outwardly projecting end of said first named means being threaded, and an adjusting knob screwed thereon and engaging said thrust member and acting together with the first named spring means to maintain said thrust member in engagement with said rotatable member to maintain fi'ictional engagement between the planular surface portion of said rotatable member and said friction pad, and cam means acting on said slidable means for moving the same in a direction against the action of said first named spring means to relieve the pressure of the thrust member on said rotatable member.

15. An upper thread tension device for a sewing machine comprising, in combination with the sewing machine head, means supported by the head and extending outwardly thereof; a member having a hub portion rotatable on said means and movable endwise relative thereto and a friction disk planular surface portion extending substantially perpendicular to said hub portion, said member also having an annular flange extending from said surface portion and concentric to said hub portion; a friction pad supported by said head and engageable by said planular surface portion, a thread receiving ring or pulley carried by said annular flange and rotatable independently relative thereto, said annular flange being provided with an arcuate slot concentric to said hub portion and said flange, a spiral spring housed between said hub portion and said annular flange and having one end connected to said hub portion and its opposite end connected to said ring or pulley by a connecting element extending through said slot wherefore said ring or pulley has independent relative rotation to said flange within predetermined limits with such rotation in one direction. acting to wind up said spiral spring, and means supported by the first named means for maintaining said surfaceportion of said rotatable member in engagement with said friction pad.

16. An upper thread tension device for a sewing machine comprising, in combination with the sewing machine head, means supported by the head and extending outwardly thereof, a member rotatable on said means and movable endwise relative thereto and including a planular circular disk surface portion and having an annular flange, a friction pad supported by said head and engageable by said surface portion, a thread receiving ring or pulley rotatably supported on said flange, said flange being provided with an arcuate slot, spring means carried by said member and connected to said ring or pulley by a connecting element extending through said slot wherefore said slot and element permit limited rotation of said ring or pulley independently of and relatively to said member, the independent relative rotation of the pulley or ring in one direction tensioning said spring means and said spring means acting to rotate the pulley or ring relative to said member in the opposite direction, and means supported by the first named means for maintaining said surface portion of said member in engagement with said friction pad.

17. An upper thread tension device for a sewing machine comprising, in combination with the sewing machine head, means supported by the head and extending r outwardly thereof, a member having a hub rotatable on said means and movable endwise relative thereto and provided at one end of said hub with a planular circular disk surface portion perpendicular to said hub, a friction pad supported by said head and engageable by said surface portion, a thread receiving ring or pulley carried concentrically by said rotatable member and located between said circular disk surface portion and the plane perpendicular to the hub in which is located the other end of the hub, said thread receiving ring or pulley having limited rotation independently of and relatively to said member, spring means carried by said member and operatively associated with said member and said ring or pulley and tensioned by the independent relative rotation of the pulley or ring in one direction and then acting to rotate the ring or pulley independently of and relatively to said member in the opposite direction, thrust means carried by said first named means and adapted to engage the other end of said hub, and means carried by said first named means and acting to apply a spring biased load on said thrust means in a direction for main- I 11 t V taining said surface. portion'of said member in engagement withsaid friction pad. 18. An upper thread tension device as defined in claim 17 and wherein means is provided for relieving the spring load on said thrust means when it is desired to do so.

19., An upper thread tension device as defined in claim 17 and wherein said circular disk surface portion of said member is provided with an annular flange concentric to said hub and of less width than the length of said hub while said ring or pulley is mounted on said flange and said spring means is located between said hub and said flange and is connected to the hub and also to the ring or pulley by a connection extending through an arcuate slot in said flange.

v References Cited in the file of this patent UNITED- STATES PATENTS Ross i Dec. 23, 1952.

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