US2178544A - Lock stitch sewing machine - Google Patents

Description

Nov. 7 1939. c. F. RUBEL LOCK STITCH SEWING MACHINE 6 Sheets-Sheet 1 Filed Jan. 30, 1937 INVENTOR; Chm Z65 I? RuZwL,

T ORNEYS.

WITNESSES.-

Nov. 7, 1939. c. F. RUBEL 2,

LOCK STITCH SEWING MACHINE Filed Jan. 50, 1937 s Sheets-Sheet 2 l2" EL 45 HG: fl

Charles I Babel,

A 'ITORNEYS.

Nov. 7, 1939. c F. RUBEL 2,178,544

LOCK STITCH SEWING MACHINE Filed Jan. 30, 1937 6 Sheets-Sheet 5 WITNESSES: INVENTOR:

Charles in" Rahal,

m f By NOV. 7, 1939. c RUBEL 2,178,544 I LOOK STITCH SEWING MACHINE Filed Jan. 50, 1937 6 Sheets-Sheet 4 W1 TNESSES; 1 4m INVENTOR:

ZZZZiZ;

A TTORNEYS.

Nov. 7, 1939. c F, RUBEL I 2,178,544 LOCK STITCH SEWING MACHINE Fil'ed Jan. 50, 1957 e sheets-sheet 5 JZIGL. AL 1" WITNESSES INVENTOR:

TORNEYS.

Nov. 1, 1939. g; F RUBEL 2,178,544

LOCK STITCH SEWING MACHINE Filed Jan. 30, 1937 6 Sheets-Sheet 6 WITNESSES; INVENTOR;

' Char Z05 i Babel,

' BY 1/ I I 1 RNEYS.

Patented Nov. 7, 1939 UNITED STATES PATENT OFFICE LOCK STITCH SEWING MACHINE poration of Illinois.

Application January 30, 1937, Serial No. 123,180

43 Claims.

This invention relates to lock stitch sewing machines, that is to say, to sewing machines of the type wherein a complimental stitch-forming means including a rotary hook cooperates with a needle in producing lock stitch seams.

Ordinarily, in sewing machines of the sort referred to, the rotating component or rotary hook has an internal circumferential raceway or groove which is engaged, with a snug working fit, by a circumferential rib on a non-rotatively held bobbin case holder about which the hook revolves. Due to friction between the extensive bearing areas of the groove and the rib of the relatively rotating components of the complemental stitchforming means, rapid wear takes place, particularly when the machines are operated at relatively high speeds, with attendant generation of excessive heat and development, after a short time, of a clearance between the sides of the groove and the rib, in which clearance the needle loop thread is pinched and severed as it crosses the groove in passing to the back of the bobbin case holder. When wear has taken place to the extent described, it is necessary to replace either the rotary hook or the bobbin case holder,. or both, at very considerable expense.

The chief aim of my invention is to overcome the above contingencies, which objective I attain as hereinafter more fully disclosed, by purposely forming the groove in the. hook wider than the rib on the bobbin case holder, so that the latter is permitted limited axial play normally with capacity to float freely while sustained solely at the periphery of its circumferential rib; and through provision of a moving steadying or buttressing element whereby said bobbin case holder is pressed inward and its axial play substantially taken up so that its rib is brought into very considerably to the life of these parts, but to enable operation of lock stitch sewing machines at much higher speeds than possible heretofore. A further advantage of my improved construction is that it dispenses with the necessity either for mgans to lubricate the rotary hook, or the use of cooling means, which heretofore, were absolutely essential to the high speed operation of lock stitch sewing machines.

Another object of my invention is to secure the above advantages with a steadying member capable of functioning as a means for retaining the bobbin case within the bobbin case holder and capable moreover, of actuation by a reciprocating part of the machine mechanism.

Another object of my invention is to provide for adjustment of the steadying'element to enable compensation for inaccuracies of manufacture as well as for wear when necessary.

Other objects and attendant advantages will appear from the following detailed description of the attached drawings, wherein Fig. I is a fragmentary view in transverse section, of a lock stitch sewing machine conveniently embodying the present improvements.

Fig. II is a fragmentary view, in plan, of the work support of the machine, with a portion thereof broken out to expose the underlying parts of the machine mechanism.

Fig. III is a fragmentary sectional view on a larger scale, taken as indicated by the arrows IIIIII in Figs. I and II, axially through the rotary hook and the parts directly associated therewith.

Fig. IV is a fragmentary sectional view taken as indicated by the arrows IVIV in Figs. IIand III.

Fig. V is a fragmentary view in longitudinal section taken as indicated by the arrows V--V in Fig. II.

Fig. VI is a view corresponding to Fig. IV showing the rotary hook in the act of drawing the needle thread loop.

Fig. VII is a fragmentary view looking as indicated by the arrows VII-VII in Fig. VI.

Fig. VIII is a view like Fig. IV showing the rotary hook further advanced in its active rotation, with the needle thread loop fully drawn.

Fig. IX is a fragmentary view partly in elevation, and partly in section taken as indicated by the arrows IX--IX in Fig. VIII; and

Fig. X is a fragmentary view in. plan on a larger scale corresponding to Fig. II, and showing the steadying element in retracted position, and the manner in which the bobbin case is removed for the purpose of thread replenishment.

With more detailed reference first more particularly to Figs. I and II of these illustrations, l designates the horizontal bed or work support of the sewing machine into which is set a throat plate 2. The needle of the machine is indicated at 3, the presser foot at 4, and feed dog by which 55 thsworksupport i,bymeansofascrewl.-At

its other and, the feed bar I has a pivotal connection at I with the top end of a rocker I which is secured to a rock shaft II supported for oscillation in pendant bracket lugs ii of the work support. Through a strap link II, the rocker I is actuated from an eccentric II on a rotary shaft II to impart horizontal to and fro or feed movements to ,the feed dog I, said rotary shaft extending longitudinally of the machine beneath the work support and being ioui'naled in suitable fixed bearings whereof one is indicated at iI in Fig. II. The straplink II is of a type comprising telescoping parts iIa, III) of which the former has a pivotal connection at I! with the lower end of a suspension arm or "lazy bar" iI fulcrumedat lItotheendofanotherarmIIona regulating shaft II which is also suitably journaled beneath the work support I. By angularly adjusting the shaft II, the feed stroke of the feeddogcanbeincreased or decreasedorthe action of said feed dog reversed after the manner set forth in U. 8. Patent Number 2,113,572 granted to Norman V. Christensen and the present applicant on April 12, 1938. Up and down or lift movements are imparted tojthe feed dog I by means of a crank II at the forward end of the rotary shaft II, through medium of a drop link a which is pivotally connected at its lower end with a downward projection II of the I. One of the characteristics of this type oi -feed mechanism is that adiustment for stitch length or for reversal is not attended by any change in the timing between the movements of the feed bar I and the needle I.

' Cooperating with the needle I below the work support I is the compiemental stitch-forming with the construction and operation I of which the present invention is more especially W ll. said being generally designated bythe numeral II. As shown. this complemental stitch-f includes a t or rotary hook II whereof Matias 'thehubIlissecuredhymeansofsetscrews II.

to anothulongitudinal shaft II, which, adjaoentitsforwardendisjournaledinabearing II beneath the work support I. By suitable means which may be of theform in the copending patent application supra,theshaftIIisdrivenfromtheshaft atmultipliedspeedsothatsaidrotaryhookII maku several revolutions (in this instance, two) foreachreciprocation oftheneedleIduringeach flange, and a loopreiealm tail II. The non-rotating component or the tal stitch-forming mechanism isintheillustratedinstanee abobbincaseholder designated II which is accommodated within oftherotaryhookII,andwhichlike the internal groove or raceway Ii of said hook. In accordance with my invention, however, the rib II is made substantially narrower in width than the groove II as a result of which the nonrotating component or bobbin case holder II is permitted to float" normally, 1. e., to freely shift axially within the limits of said groove while sustained solely at the periphery of its rib as shown in Fig. 111. As ordinarily. the rib II of the bobbin case holder II is interrupted for a 10 short distance as at II with consequent provision of a loop-clearing interval and a loop-arresting shoulder II. The bobbin caseholder II is prevented from rotating with the hook II due to engagement of a frontal vertical notch II at the top of its face flange II by the lateral projection of a detaining finger II secured to the underside of the work support i by screws II, see Figs. L-HI. Housed within the hollow of the holder II is a removable bobbin case 4 8 which is closed so at the front except for a pair of vertical openings II at opposite sides of a central vertical bar Iii. Extending inwardly from the bar II axially of the bobbin case II is a tubular boss II which freely engages a central stud as in the u of the holder II, whereby it is restrained against rotation with the rotary component or hook II. Near the top and at the front, the bobbin case II is formed, in accordance with my invention, with a beveled surface II for camming action with a correspondingly beveled surface II of a buttressing'or steadying element II whereof the shank I9 is adjustable both longitudinally and rotatively in the upwardly inclined free end of a supporting arm 80, and securable in adjustable positions by a set screw Ii. it will be observed that the arm 60 underreaches the feed bar I, and is fulcrumed on a screw stud II engaging upwardly into said bar. A torsion spring II with its coil surrounding the fulcrum hub of the arm II, tends to swing said arm horizontally outward away from the bobbin case II to the retracted position shown in Fig. x against a stop II fixed in the work support I. When the arm II is retracted as just described, it will be seen that the rotary hook is readily accessible for convenience in removing the bobbin case II when thread replenishment is necessary; Normally, however, the arm II is held in its operative position between vertically-spaced bracing lugs II on the downward projection II of the feed bar I in opposition to the influence of the spring II, see Figs. I, II and Y. by a hook detent or latch II which latter is pivoted at II to the front end of said projection. As shown in Fig. V, the

hook detent u is yieldingly urged upwardly by 9 the arm II is swung inward from the retracted position shown in Fig. X, the latch I1 is automatically depressed through coaction of the bevel edge II at its free end with the bottom edgeofsaidarm. l'inallywhenthe armIIis again lodged between the lugs II in the pendant projection II of the feedbar I, the latch I1 is .lifted by its spring II to the locking position showninl'imv. ReleaseofthearmIIiseffectedsimplybypressingdownthefreeendof From Figs. I and II. 40

the latch 61 in a manner which will be obvious from Fig. V.

The stitch-forming cycle of the machine is as follows: By virtue of the connection of the steadying element 58 to the feed bar 6, the center P of its bearing surface 56 is moved in an irregular elliptic orbit as shown in dot and dash lines at 13 in Figs. IV, VI and 'VIII. At the beginning of the first revolution of the rotary hook 26 during each stitch-forming cycle immediately after the needle 3 has penetrated the fabric F, the needle thread T is engaged by the hookbeak 33 and directed into the throat 35 by coaction of the guard spur 34 as shown in Fig. VI, with the rearwardly-deflected inner limb L of the loop intercepted by the arresting shoulder of, the rib 39 and resting on the surface of the holder body 40 crosswise of the groove 3| and with a portion 1' thereof lying, as shown in Fig. VII, substantially parallel to the inner shoulder of said rib and the corresponding inner shoulder of said groove. If, in a rotary hook of ordinary construction a clearance substantially equal to the thickness of the needle thread exists at the region of the shoulder 42, the needle thread is pinched between the rib and the side of the groove and severed as the hook advances in its rotation. In the complemental stitch-forming means of my invention such contingency is precluded by positive maintenance of the rib 39 in close proximity or light bearing contact with the rear shoulder of the groove 3! at this critical period in the manner about to be explained. By light contact, I mean that the rear side face of the rib 39 is brought sufficiently close to the contiguous rear shoulder of the groove 3! to preclude entry and pinching of. the loop thread between them. contemporaneous with the events just described, the feed dog 5 is in its lowermostposition and moving through its idle stroke as indicated by the arrow on the orbit ellipse 73 in Fig. VI, with the steadying element 58 bearing full upon the inclined surface 55 of the bobbin case 48, and hence with the inner shoulder of the rib 39 of the holder substantially in engagement with the inner shoulder of the hook groove 3| so that pinching of the needle thread T cannot possibly occur as heretofore. This condition obtains while the point P moves rightward along the short lower flat stretch of the orbit ellipse 73 (corresponding to substantially a quarter rotation of the shaft 15) and while the hook 28 makes substantially a half rotation from the moment of first engaging the needle thread T, through the position of Fig. VI, to the position of Fig. VIII when the needle thread loop is substantially full drawn. During this interval, the front limb L of. the loop is drawn down over the front faces of the bobbin case holder flange 68 and the bobbin case 48, and the inner limb L wrapped further about the cylindric body 40 of the bobbin case holder 38 as shown. As the hook 26 continues in its rotation from the position of Fig. VIII, the center P moves upward of the right hand end of the orbit ellipse 13, with attendant separation of the steadying element 58 from the beveled surface 55 of the bobbin case so that the front limb L of the needle thread 'I' can pass between them as shown in Fig. IV as the loop is fully draw'n. From then on, the steadying element 58 remains clear of the bobbin case 48 during the remainder of. the active loop drawing rotation of the rotary hook as well as during the whole of the succeeding or idle rotation of the hook as the point P moves along the upper portion of its elliptic orbit, while the feed dog 5 performs its active stroke in progressing the fabric F on the work support I of the machine and incidentally determines the stitch length.

In moving around the bobbin case holder 38, the needle thread loop is, of course, interengaged in the usual way with the bobbin thread which is indicated at T in Figs. IV, VI and VIII. Thus, in accordance with my invention, the bobbin case holder 38 is'restrained against axial movement only for a short period during the initial part of each stitch-forming cycleto be exact, during less than a half revolution of the first rotation of the rotary hook in such cycle-so that said holder is normally free to float sustained solely on the periphery of its circumferential rib 39. This is obviously advantageous since it not only eases passage of the needle thread about the bobbin holder, but precludes overheating and rapid wear of the relatively rotating components of the cooperative stitch-forming means. As a consequence, the sewing machine can be safely operated at high speeds which were heretofore regarded as excessive. In this connection it is to be noted that the effective motion of the steadying element 58 results from the up and down component rather than from the horizontal component of movement of the feed bar. Accordingly the action of the element 58 will be the same during reversal of the feeding mechanism as in the normal operation of the latter. In other words, since the timing between the needle 3 and the feed bar 6 remains unchanged by adjustments of the feed mechanism for stitch length or for reversal as already pointed out hereinbefore, it also follows that the instant of taking up the axial play between the bobbin case holder and the rotary hook will always occur at the same time during each stitch forming cycle.

In order to facilitate spreading and casting of the needle thread loop toward the back of the bobbin case holder 38, the thread-arresting shoulder 42 of the rib 39 is cut back somewhat more than usual. must travel somewhat further than ordinarily before the thread T is engaged by the shoulder 42, thereby allowing a little more time than ordinarily for the inner limb L of the loop to be carried rearwardly and outwardly along the angularly receding inner edge of said beak, the loop being therefore spread wider and therefore more easily cast off.

When required to compensate for wear of the parts after long periods of service or to adapt the sewing machine for use of threads of different gauges, the steadying element 58 may be adjusted in the arm 68 upon loosening the set screw 6i.

My invention is not necessarily restricted to the use of the feed mechanism of the sewing machine as a means for actuating the steadying element 58 to periodically restrain the bobbin case holder of the complemental stitch-forming means, since, if desired or found more convenient in practice, it may be coordinated with any other moving part of the machine. mechanism and its cam face variantly shaped in order that it may function in the way herein set forth.

Having thus described my invention, I claim:

1. In a lock stitch sewing machine, stitchforming mechanism including two relatively rotating components, said components being operatively interconnected with provision for limited endwise play; and moving means operative to Accordingly the loop-seizing beak 33' take up the end play between said components during a portion of each stitch-forming cycle.

2. In a lock stitch sewing machine, stitchforming mechanism including two relatively rotating components, said components being operatively interconnected with provision for limited endwise play; and means operative to periodically engage one of said components for taking up the end play between it and the other component during a portion of each stitch=forming cycle. 3. In a lock stitch sewing machine, stitchforming mechanism including a rotatable com ponent and a non-rotatable component, said components being operatively interconnected with provision for limited endwise play; and means operative to periodically engage one of said components for taking up the end play between it and the other component during a portion of each stitch-forming cycle.

4.111 a lock stitch sewing machine, stitchformlng mechanism including a rotatable com ponent and a non-rotatable. component, said components being operatively interconnected with provision for limited endwise play; and means operative to periodically engage the non-rotatable component for taking up the end play between it and therotatable component during a portion of each stitch-forming cycle.

5. In a lock stitch sewing machine, stitchforming mechanism including two relatively rotating components, one axially within the other, said components being operatively interconnected with provision for limited endwise play; and

' moving means operative to take up the end play between said components during a portion of each stitch-forming cycle.

6. In a lock stitch sewing machine, stitchforming mechanism including two relatively rotating components, one axially within the other; and having a circumferential rib and groove in-- terengagement with provision normally of 'limited endwise play; and means operative to periodically engage one of said components to maintain one side of the rib in bearing contact with the corresponding side of the groove during a portion of each loop-forming cycle.

7. In a lock stitch sewing machine, stitchforming mechanism including two relatively rotating components, said components being operatively interconnected with provision for limited endwise play; and means operative to take up the end play between said components during the initial portion of each stitch-forming cycle.

8. In a lock stitch sewing machine, stitchforming mechanism including two relatively ro tating components, said component's being operatively interconnected with provision for limited endwise play; a steadying element operative by camming action with one of said components to take up the and play existing between the latter and the other component during a portion of each stitch-forming cycle.

9. In a lock stitch sewing machine a needle; cooperative stitch-forming mechanism including a rotary hook and a non-rotatable bobbin case holder whereof one has a circumferential groove and the other a corresponding but narrower cooperating rib, whereby the two are held assembled with capacity for limited relative axial play normally; and means operative to positively maintain said elements against relative axial play, with a side of the rib on the one in engagement withthe contiguous side wall of the groove in the other, during the interval in each stitch-forming oyclewhentheinnerleg'oi' the needlethreadloop cycle.

passes across said groove toward the back of the bobbin case holder.

10. In a lock stitch sewing machine, a needle; cooperative stitch-forming means including a rotary hook making several revolutions during each stitch-forming cycle, said hook having an internal circumferential groove, a non-rotative bobbin case holder with an external circumferential rib corresponding in. diameter to that of the groove of the rotary book but of a lesser width, whereby said holder normally has limited axial play, and a bobbin case within the holder; and a steadying element operative to press upon the bobbin case so that the back wall of the circumferential rib of the bobbin case holder bears upon the contiguous wall of the hook groove during a portion of one of the several revolutions of said hook at the time when the inner limb of the needle loop passes across said groove toward the back of the bobbin case holder. 11. In a' lock stitch sewing machine, a reciprocating needle; cooperative stitch-forming mechanism including a non-rotatable component and a rotatable component making several rotations for each reciprocation, of the needle during each stitch-forming cycle, said components being operatively interconnected with provision for limited endwise play: and means operative to take up the end play between said components during a portion of one revolution of the rotatable component.

12. In a lock stitch sewing machine, a reciprocating needle; cooperative stitch-forming mechanism including a non-rotatable component, and a rotatable component making several rotations for each reciprocation of the needle during each stitch-forming cycle, said components being operatively interconnected with provision for limited endwise play; and means operative to take up the end play between said components during a portion of the first revolution of the rotatable component during each stitch-formin 13. In a lock stitch sewing machine, feed mechanism; stitch-forming mechanism including two relatively rotating components, said components being operatively interconnected with provision. for limited endwise play; and means deriving motion from the feed mechanism operative to take up the end play between said components during a portion of each stitch-forming cycle.

14. In a lock stitch sewing machine, feed mechanism; stitch-forming mechanism including two relatively rotating components, said components being ratively interconnected with provision for i ted endwise play; and means deriving motion from the feed mechanism operative to take up the end play between said components during the initial portion of each stitch-forming cycle. l5. Ina lock stitch sewing machine, a feed dog and means for reciprocating it once for each stitch-forming cycle; stitch-forming m'echanism including a non-rotatable component, and s. rotatable component making several rotations during each stitch-forming cycle, said components being operatively interconnected with provision for limited endwise play: and means connected to the feed mechanism and operative to take up the end play between said components during a portion of one of the revolutions of said rotatable component during each stitch-forming cycle.

.. 16. In a lock stitch sewing machine, a feed dog and means for reciprocating it once for cash.

stitch-forming cycle; stitch-forming mechanism. is

including a non-rotatable component and a rotatable component making several rotations during each stitch-forming cycle, said components being operatively interconnected with provision for limited endwise play; and means connected to the feed mechanism and operative to take up the end play between said components during a portion of the first revolution of said rotatable component during each stitchi-forming cycle.

17. In a lock stitch sewing machine, a needle; cooperating stitch-forming means including a rotary hook with an internal circumferential groove, a non-rotatable bobbin case holder within the rotary hook having an external circumferential rib corresponding in diameter to the groove of said hook but of a lesser width, whereby the bobbin case holder normally has limited axial play, and a bobbin case within the holder; a retractable element for maintaining the bobbin case in place within the holder; and means for periodically actuating said element to press against the bobbin case so that the back wall of the circumferential rib of the bobbin case holder bears upon the contiguous wall of the hook groove during a portion of each stitch-forming cycle.

18. In a lock stitch sewing machine, stitch loop forming mechanism including two relatively rotating coaxial components normally out of endwise bearing contact; and means for bringing said components into endwise bearing contact during a portion of each stitch loop forming cycle to insure against entry and pinching of the loop thread between them.

19. In a lock stitch sewing machine, stitch loop forming mechanism including two relatively rotating coaxial components, one having a circumferential rib and the other a circumferential rib receiving groove which is somewhat wider than the rib for allowance of a limited amount of endwise play between said components normally; and means for bringing said components into endwise bearing contact during a portion of each stitch loop forming cycle to insure against entry of the loop thread and pinching thereof between contiguous side faces of the rib and the groove.

20. In a lock stitch sewing machine, stitchforming mechanism including a rotary hook, a non-rotating bobbin case holder within the rotary hook, and a bobbin case within said holder, said hook and bobbin case holder being interconnected with provision for limited endwise play; a steadying element adapted to coact with the front face of the bobbin case in taking up the end play between the' bobbin case holder and the rotary hook during a portion of each stitch-forming cycle; and actuating means supporting said steadying element with capacity to be retracted out of the way for freedom of access to the bobbin case for the purpose of thread replenishing.

21, In a lock stitch sewing machine, stitchforming mechanism including a rotary hook, a non-rotating bobbin case holder within the rotary hook, and a bobbin case within said holder, said hook and bobbin case holder being interconnected with provision for limited endwise play; a steadying element adapted to coact with the front face of the bobbin case in taking up end play between the bobbin case holder and the rotary hook during a portion of each stitch-forming ing cycle; and actuating means pivotally supporting said steadying element with capacity to be swung to a retracted position for freedom of access to the bobbin case for the purpose of thread replenishing,

22. In a lock stitch sewing machine, stitchforming mechanism including a rotary hook, a non-rotating bobbin case holder within the rotary hook, and a bobbin case within said holder, said hook and bobbin case holder being interconnected with provision for limited endwise play; a steadying element adapted to coact with the front face of the bobbin case in taking up the end play between the bobbin case holder and the rotary hook during a portion of each stitchforming cycle; actuating means supporting said steadying element with capacity to be retracted out of the way for freedom of access to the bobbin case for the purpose of thread replenishing; spring means tending to move the steadying element to its retracted position; and latch means to'normally maintain said element in its operative position.

23. Lock stitch mechanism for a sewing machine comprising a pair of relatively rotating components normally out of endwise contact; a bobbin case within one of said components; and means for retaining the bobbin case in the last mentioned of said components and operative to intermittently bring the two components into endwise bearing contact so as to prevent entry of thread between their contiguous side faces.

24. Lock stitch mechanism for sewing machines comprising a rotating component and a non-rotating component normally out of endwise bearing contact; a bobbin case within the nonrotating component; and means for retaining the bobbin case within the non-rotating component and operative to intermittently bring the two components into endwise bearing contact so as to prevent entry of thread between their contiguous side faces.

25. In a lock stitch sewing machine, stitch loop forming mechanism including two coaxial components, one of which rotates in relation to the other without constant endwise bearing contact and means for establishing such an endwise bearing contact between the relatively rotating elements once during each cycle of stitch formation.

26. In a lock stitch sewing machine, stitchforming mechanism including a rotating component with a circumferential shoulder; a nonrotating component with a circumferential rib which is'interrupted to provide a needle loop detaining horn; and a member for limiting outward axial play of the non-rotating component so that its rib is normally out of contact with the circumferential shoulder of the rotating component; said member having a single spot projection between which and the non-rotating component, one limb of the needle loop is adapted to pass.

2'7. In a lock stitch sewing machine, stitchforming mechanism including a rotating component with a circumferential shoulder; a nonrotating component with a circumferential rib which is interrupted to provide a needle loop detaining horn; and a member for limiting outward axial play of the non-rotating component so that its rib is normally but of contact with the circumferential shoulder of the rotating component, said member having a single spot projection lying substantially in the vertical plane of the axis of the rotating component, between which projection and the non-rotating component, one limb of the needle loop is adapted to pass.

28. In a lock stitch sewing machine, stitchforming mechanism including a rotating component with a circumferential shoulder; a nonrotating component with a circumferential rib which is interrupted to provide a needle loop detaining horn; a member for limiting outward axial play of the non-rotating component so that its rib is normally out of contact with the circumferential shoulder of the rotating component, said member having a single spot projection between which and the non-rotating component, one limb of the needle loop is adapted to pass; and means for imparting orbital movement to said projection in a plane parallel to that of the non-rotating component.

29. In a lock stitch sewing machine, stitchforming mechanism including a rotating component with an internal circumferential groove; a non-rotating component with a circumferential rib engaging the groove of the rotating component, said rib being interrupted to provide a needle loop detaining horn and being narrower than the groove so that it is normally out of contact with both sides of said groove; and a member for limiting outward axial play of the non-rotating component, said member having a single spot projection between which and the non-rotating component, one limb of the needle loop is adapted to pass.

80. In a lock stitch sewing machine, stitchforming mechanism including a rotary hook with an internal circumferential groove; a non-rotating bobbin case holder with a circumferential rib which is interrupted to provide a needle loop detaining horn and which is narrower than the groove; a bobbin case within the bobbin case holder; and a member for limiting outwlard axial play of the bobbin case holder so that the rib of the latter is normally out of contact with both sides of the groove in the rotary hook, said member having a single spot projection between which and the front face of the bobbin case, one limb of the needle loop is adapted to pass.

81. In a lock stitch sewing machine, stitchforming mechanism including a rotating component with an internal circumferential groove: a non-rotating component with a circumferential rib which is interrupted to provide a needle loop detaining horn and which is narrower than the groove: a member for limiting outward axial play of the non-rotating component so that its rib is normally out of contact with both sides of the groove in the rotating component, said member having a single spot projection between which and thenon-rotating component one limb of the needle low is adapted to pass: and means for im-' 82. In a lock stitch sewing machine, stitchv forming mechanism including a rotary hook with an internal circumferential groove; a rotating bobbin case holder with a circumferential rib which is interrupted to provide a needle loop detaining horn and which is narrower than the groove a bobbin'case within the bobbin case holder having a cam surface on its front face; and a member for limiting outward axial play of the bobbin case holder so that the rib of the latter is normally out of contact with both sides of the groove in the rotary hook, said member having a single spot projection between which and the cam surface on the bobbin case, one limb of the needle loop is adapted to pass.

88. In a lock stitch sewing machine, stitchforming mechanism including a rotary hook with an internal circumferential groove; a non-rotating bobbin case holder with a circumferential rib which is interrupted to provide a needle loop detaining horn and which is narrower than the groove; a bobbin case within the bobbin case holder having a cam surface on its front face; a member for limiting outward axial play of the bobbin case holder so that the rib of the latter is normally out of contact with both sides of the groove in the rotary hook, said member having a single spot projection between which and the cam surface on the bobbin case, one

limb of the needle loop is adapted to pass; and

means for imparting orbital movement to said member in a plane parallel to that of the bobbin case holder.

34. In a lock stitch sewing machine, a reciprocating needle; complemental stitch-forming.

means including a rotating component adapted to revolve twice for each reciprocation of the needle and having a circumferential shoulder, and a non-rotating component with a circumferential rib which is interrupted to provide a needle loop detaining horn; and a member for limiting outward axial play of the non-rotating component, said member having a single spot projection-between which and the non-rotating component, one limb of the needle loop is adapted to pass, said spot projection lying in a vertical plane through the axis of the rotating component at a level above the latter.

35. In a lock stitch sewing machine, a reciprocating needle; complemental stitch-forming means including a rotating component adapted to revolve twice for each reciprocation of the needle and having a circumferential shoulder, and a non-rotating component with a circumferential rib which is interrupted to provide a needle loop detaining horn; a member for limiting outward axial play of the non-rotating component, said member having a single spot projection lying in a vertical plane through the axis of the rotating component at a level above the latter between which spot projection and the non-rotating component, one limb of the needle loop is adapted to pass; and means for imparting orbital movement to said member in a plane parallel 4 to that of the non-rotating component.

36. In a lock: stitch sewing machine, a reciprocating needle; complemental stitch-forming means including a rotary hook adapted to revolve twice for each reciprocation of the needle and having a circumferential groove, a non-rotating bobbin case holder with a circumferential rib which is interrupted toprovide a needle loop detaining horn and which is narrower than the groove, and a bobbin case within the bobbin case holder having a cam surface on its front face;

a member for limiting outward axial play of v the bobbin case holder so that the rib of the latter is normally out. of contact with both sides of the groove in the rotary hook, said member having a single spot projection between which and the cam surface on the bobbin case, one limb of the needle loop is adapted to pass; and means for forming mechanism including a hollow rotary hook component and a non-rotating bobbin holder component within the hook component, said components having opposing circumferential shoulders normally out of contact; and periodically actuated abutment means operative upon one of said components to cause light momentary contact between the shoulders at a time in each stitch-forming cycle when the tendency of the needle thread to enter between said forming mechanism including a hollow rotary hook component and a non-rotating bobbin holder component within the hook component, said components having opposing circumferential shoulders normally out of contact; and intermittently actuated abutment means operative upon one of-said components to cause rapidly recurring light momentary contacts between the shoulders, said abutment means occupying a retracted position relative to said one component at the time when 'the needle thread passes between the contact surfaces of said abutment means and said one component.

40. A look stitch sewing machine with stitchforming mechanism including a rotary component and a non-rotating component having capacity for relative axial play; and moving means for periodically reducing the axial play between said components.-

41. A look stitch sewing machine including a reversible feeding mechanism; stitch-forming mechanism comprising a rotary component and a non-rotating component having capacity forrelative axial play; and means deriving motion from the reversible feeding mechanism for pcriodically reducing and substantially taking up the axial play between said components.

42. A look stitch sewing machine comprising a needle; feeding mechanism including a moving member, means for actuating the moving member, and means whereby the movements of the member may be adjusted for ariation of stitch length without change in the timing thereof in respect to the movements of the needle; complemental stitch forming mechanism including two relatively rotatable components which have capacity for limited axial play; and means connected to the moving member of the feeding mechanism for taking up the axial play between the aforesaid components during a portion of each stitch forming cycle.

43. A look stitch sewing machine comprising a needle; feeding mechanism including a moving member, means for actuating the moving member, and means whereby the movements of the member may be reversed without change in the timing of said member in respect tothe movements of the needle; complemental stitch forming mechanism including two relatively ro=- tatable components which have capacity for limited axial play; and means connected to the moving member of the feeding mechanism for taking up the axial play between the aforesaid components during a portion of each stitch forming cycle.

CHARLES F. RUBEL.

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