US2129402A - Sewing machine - Google Patents

Description

Sept. 6, 1938. L. s. BOWMAN ,1

SEWING MACHINE Filed Sept. 27, 1955 15 Sheets-Sheet l Q PB:

INVENTOR. 1702a; G. aowmazu.

ATTORNEY Sept. 6, 1938. 1.. G. BOWMAN- 2,129,402

7 SEWING MACHINE Filed Sept/2'7, 1955 15 Sheets-Sheet 2 IN VEN TOR.

A TTORNEY Sept. 6, 1938. G. BOWMAN SEWING MACHINE Filed Sept 27, 1955 15 Sheets-Sheet 5 INVENTOR.

Z0242 G-Jowmam ATTORNEY L. G. BOWMAN SEWING MACHINE Sept. 6, 1938.

Filed Sept. ,27, 1955 15 Sheets-Sheet 4 INVEN'TOR. lZzzzJ 6- Jawmam I ATTORNEY Sept. 6, 1938.

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. ATTORNEY Filed Sept. .27, 1935 Sept. 6, 1938. L. G. BOWMAN.

SEWING MACHINE Filed Sept. 27, 1935 15 Sheets-Sheet e INVENTOR. lauds G. @owman. BY'

A TTORNEY Sept. 6, 1938. L. G. BOWMAN SEWING MACHINE Filed'Sept. 2'7, 1935 15 Sheets-Shee '7 gWQ A I INVENTOR. I Iouw aowmm.

TTORNEY A 22/ lm L. G. BOWMAN SEWING MACHINE Sept. 6, 1938.

Filed Sept. 27, 1935 15 SheetS-Sheet 8 kkwu E INVENTOR. IOZZ J G. owmam.

ZZTTORNEY SEWING MA NE Filed Sept. 27, 1935 15 Sheets-Sheet 9 I NTOR. Iaui G. :Zawm

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ATTORNEY Sept. 6, 1938. G. BOWMAN SEWING MACHINE Filed Sept. 27, 1955 15 Sheets-Sheet 10 INVENTOR. Iouzli G. owmm BY 18? "7Z3:

A TTORNEY L. G. BOWMAN SEWING MACHINE Sept. 6, 1938.

Filed Sept. 27, 1935 15 Sheets-Sheet 11 INVENTOR. 02428 6. 5owmam l BY 5 j ATTORNEY- Sept. 6, 1938. 1.. G. BOWMAN 2,129,402

SEWING MACHINE Filed Sept. 27, 1935 15 Sheets-Sheet 12 i I I i i l l l INVENTOR Zouw 6. czowman.

ATTORNEY Sept. 6, 1938.

| G. BOWMAN SEWING MACHINE Filed Sept. 2'7, 1935 15 Sheets-Sheet l3 1N VEN TOR. 17020.5 61. czawmam.

BY Ta l-fm A TTORNEY Sept. 6, 1938. L. G. BOWMAN I SEWING MACHINE File d Sept. 27, 19:55

15 Sheets-Sheet 14 i INVENTOR.

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BY ATTORNEY 15 Sheets-Sheet 15 Sept. 1938. G. BOWMAN} SEWING MACHINE Filed Sept. 27; 1935 IN V EN TOR. $0 wmam' "7325- A TTORNE Y I 5 w. IN T M. m 1 R Ida BY 5* Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE SEWING MACHINE Application September 27, 1935, Serial No. 42,547

31 Claims.

This invention relates to new and useful improvements in sewing machines generally, although more particularly to those of the blind stitch type.

Sewing machines have heretofore been devised which are capable of forming anchor and skip stitches in alternation. In the Mueller Patent 2,018,186, Oct. 22, 1935, there is disclosed a machine in which is embodied means for forming blind stitches, means for normally projecting the hem fold and body fabric and then the hem fold only into position for needle penetration whereby alternate anchor and skip stitches will be formed. There is provided also manually controllable means for causing the formation of successive anchor stitches without forming any skip stitches.

An object of my invention is to provide novel and improved mechanisms for forming anchor and skip stitches, there being included adjustable devices by employment of which the operator is enabled to effect the formation of a succession of anchor stitches; or alternated anchor and skip stitches, there being one skip stitch intervening each pair of anchor stitches; or alternated anchor and multiple skip stitches, there being a multiple of skip stitches intervening each pair of anchor stitches.

With this and other objects in view which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

In the drawings:-

Figure l is a front elevation of the machine.

Figure 2 is a right end elevation.

Figure 3 is a left end elevation.

Figure 4 is a rear elevation.

Figure 5 is a top plan View.

Figure 6 is a horizontal section through the standard at the point of pivot of the work support or table, portions of the latter being shown broken away and in section.

Figure '7 is a face View of the larger gear of the l-to-Z ratio set of gears.

Figure 8 is a face view of the larger gear of the l-to-4 ratio set of gears.

Figure 9 is a detail vertical longitudinal section through the axis of the gear ratio selecting mechanism. Figure 10 is a detail perspective View of the pivoted lever by which the gear ratio selection is made.

Figure 11 is a detail vertical sectional view illustrating the dual spring mounting of the work support or table.

Figure 12 is a somewhat diagrammatic vertical cross sectional View illustrating the ridge forming element shifting devices shifted to position 5 for causing the formation of an anchor stitch during each needle operation or main shaft rotation, the 1-to-2 gear ratio being shown as effective.

Figure 13 illustrates the position of the ridge forming element and operating cam effected by the position of theparts as shown in Figure 12.

Figure 14 is a detail vertical longitudinal section taken along the axis of the pivot pin shifting means shown in Figure 12. 15

Figure 15 is a somewhat diagrammatic vertical cross sectional view illustrating the ridge forming element shifting devices shifted to position for causing the formation of a single anchor stitch during each fourth needle operation or main shaft rotation, skip stitches alone being formed during intervening needle operations or main shaft rotations, the l-to-4 gear ratio being shown as effective.

Figure 16 illustrates the position of the ridge formingelement and operating cam effected by the position of the parts as shown in Figure 15.

Figure 17 is a detail horizontal section taken along the axis of the spring pin which yieldably retains the adjustment of the pivot pin shifting lever.

Figure 18 is a somewhat diagrammatic vertical cross sectional view illustrating the ridge forming element shifting devices shifted to position for causing the formation of a single anchor stitch during every other needle operation or main shaft rotation and skip stitches during the intervening alternate needle operations or main shaft rotations, the 1-to-2 gear ratio being shown as effective.

Figure 19 illustrates the position of the ridge forming element and operating cam effected by the position of the parts shown in Figure 18.

Figure 20 is a detail vertical longitudinal section through the ridge forming element support cam plate and its mounting.

Figure 21 is an enlarged detail plan view illustrating the work clamp and the supportingtable extension end.

Figure 22 is an inverted plan view of the parts shown in Figure 21, the protective casing member being shown removed. v

Figure 23 is a detail sectional view illustrating the transverse pivot mounting and spring support of the work clamp.

Figure 24 is a somewhat diagrammatic sectional view illustrating the feature of automatically releasing thread tension by depression of the work support or table.

Figure 25 is a detail view illustrating the driving connections for the needle.

Figure 26 is a detail inverted plan view of the sewing head and the parts supported thereon.

Figure 27 is a detail plan View of the rigid presser foot and thread looper removed from their support.

Figure 28 is a detail cross section taken on the line 28-28 on Figure 27.

Figure 29 is a detail cross section taken on the line 29-29 on Figure 27.

Figure 30 is a detail longitudinal section taken on the line 3030 on Figure 27.

Figure 31 is a detail view illustrating the driving connections for the thread looper.

Figure 32 is a detail perspective view of the needle shaft take-up bearing.

Figure 33 is a detail perspective View of the extension bearing for the main shaft.

Figure 34 is a diagrammatic plan view illustrating the formation of a series of anchor stitches, the thread arm or looper being shown in the process of laying the needle thread over the edge of the hem fold.

Figure 35 illustrates the completion of the thread laying movement shown in Figure 34, the needle being shown in the process of carrying the needle thread through the loop laid by the thread looper fingers. I

Figure 36 illustrates the continuation of the stitch formation shown in Figures 34 and 35, the needle having receded and left a slack needle thread which has been taken up by the hook and is being passed around the bobbin thread, and the thread looper being shown as starting toward formation of its function shown in Figures 34 and 35.

Figure 37 is a detail view of the thread looper end and illustrates the manner in which the yieldable thread looper finger clears the needle in receding from the thread laying function shown in Figure 35.

Figure 38 is a detail end elevation of the thread looper.

Figure 39 is an enlarged somewhat diagrammatic plan View of a portion of a seam showing a plurality of anchor stitches at each end and alternate skip and anchor stitches intermediate said ends.

Figure 40 is a View similar to Figure 39 and illustrates the seam embodying anchor stitches at the beginning or left hand end and a single anchor stitch spaced by three skip stitches or one anchor stitch in each four needle operations ormain shaft revolutions following said initial anchor stitches.

Figure 41 is a detail crosssectional View taken on the line 4l-4l on Figure 39.

Figure 42 is a detail cross sectional view taken on the line 42--42 on Figure 39.

Like reference numerals designate corresponding parts throughout the several figures of the drawings.

My improved machine embodies a main frame including a base 5, a standard 6, an overhanging or laterally extending arm I, and a sewing head 8 which is secured to the free end of said arm.

A main shaft 9 equipped with the usual handwh-eel Ill and drive pulley H is journaled in the arm and sewing head in bearings I2 and [3, the latter being in the nature of a long hub mounted wear appearing at the thrust end first.

in the abutting walls of the arm and head and having a U-shaped extension l4 providing an auxiliary bearing portion l spaced from said hub. See Figures 4, 5 and 33.

Considering the direction of feed of the fabric as being away from the operator, the head 8 is equipped with a forward extension providing a needle shaft bearing support portion 16, a complemental stitch forming mechanism support portion I! and a drive housing portion l8.

Rigidly secured as at l9 to the under face of and projecting from the support portion I1 is a. horizontal presser foot 20 having formed therein a longitudinal opening 2| effective during the sewing operation to receive a ridge of material, and a hem guide 22; the latter being removably secured as at 23 to said foot.

The stitch forming mechanism includes a reciprocatory needle 24 which is oscillatable angularly across the opening 2| as shown in Figures 5 and 27. The needle is attached to a needle arm 25, and the latter is clamped as at 26 to the forward end of an oscillatory needle shaft 21 which is journaled in a bearing sleeve 28 supported in the bearing support portion I6. It will be observed by reference to Figures 1, 5 and 32 that the sleeve 28 has its end formed in the nature of a split clamp which facilitates the taking up of undesirable shaft clearance and thus tends to assure very accurate needle action. It will be understood that bearings with a thrust motion at one end wear unevenly, the y taking up slightly at the split clamp end of my improved bearing sleeve 28 wear can be compensated for and the life of the bearing materially prolonged. The bearing sleeve 28 being only partially split, the desired wear take-up adjustment may be effected without danger of binding the needle shaft 21. The needle shaft 2'! is held against end play by a collar 30.

The crank arm 3| is secured to the needle shaft and is link-connected as at 32 to one end of a forked bell crank lever 33 which is pivoted as at 34 in the sewing head 8, the fork embracing a block and eccentric equipment 35 as shown in Figures 5 and 25 so that the rotary motion of the main shaft 9 will be transmitted in, the form of oscillatory motion to the needle.

Cooperating with the needle 24 is a complementary stitch forming mechanism for forming a line of lock stitches and which in this particular disclosure includes a rotary hook 36 carried by a driven shaft 31. The shaft 31 is rotated through the means of bevel gear unit 38 from a driver shaft 39 rotatably supported in the housing portion l8 and which is in turn driven by bevel gear unit 40 with the main shaft 9. It will be observed by reference to Figures 4 and 5 that the hook driving gear unit 40 is disposed in close relation to the extended bearing portion l5, and consequently all tendency toward undesirable fiexure or freedom of the main shaft at this point is thus avoided.

A work support or table 4| is pivotally supported at 42 on a horizontal shaft 43 supported in and extending laterally from the frame standard 6 in parallelism with the main shaft 9. The support 4| includes an upstanding guard flange portion 44 and a slightly depressed portion 45 which extends laterally from said support beneath the presser foot 20 as shown in Figure 1.

A vertically yieldable work clamp 46 is carried by the lateral extension 45 and includes a downwardly-turned receiving end 41, openings 48 for accommodating a feed dog, and an opening 49 for permitting vertically reciprocatory movement of a ridge forming element.

The work clamp 46 is pivotally supported as at 50 for fore and aft tilting movement on a carrier 5| which is in turn pivotally supported at 52 for lateral tilting movement on a post 53. The post 53 is vertically reciprocable in a bore 54 formed in the lateral extension 35 and is yieldably pressed upwardly in opposition to the presser foot 20 by retractile springs 55 anchored in bores 56 and connected to the cross pin 51 secured to the lower end of the post. It will be noted that the pivot 52 of the work clamp is off center and a cushioned spring 58 is provided to balance the position of said clamp. See Figures 6, 21, 22 and 23.

The function of the work clamp 46 is to hold the material securely during the sewing operation. When the feed dog has descended, the ridge forming element rising at this time and coming in contact with the material would draw it unevenly if it were not held securely on all sides, causing the needle penetrations to vary. Therefore the work clamp is permitted to rock laterally to take care of uneven thicknesses at the right and left hand sides of the ridge forming element, and also to rock fore and aft to take care of the same conditions in front as W811 as in back of the ridge forming element, and

to allow the seam to feed freely. To further accommodate the conditions stated the work clamp is pivoted off center as shown at 52 in Figure 23. The positioning of the post 53 offcenter also avoids the necessity of otherwise placing it too far forward, and the coil spring 58 compensates for tilting tendencies of the clamp by reason of its off-center mounting and tends to hold the clamp level.

A feed dog 59 is of the usual l-motion type and for effecting this movement I employ a feed travel shaft 60 and a feed lift shaft 6|, said shafts being supported beneath the work support 4| in parallelism with each other and with the main shaft 9. The shaft 66 is provided at its left hand end with a crank 62 and the shaft 6| -with a similar crank 63, the former being link-connected as at 64 with the feed dog and the latter being connected as at 65 to one end of a lever 66 which is connected at its other end with a lower extremity of the post 53 and intermediately of its ends, by a link 68, with said feed dog. See Figures 3, 6, 22 and 23.

At their right hand ends the shafts 60 and 6| are respectively equipped with cranks 69 and 10, the former being connected by a link H with one arm of a bell crank lever l2 and the latter by a link 13 with one arm of a bell crank lever '14 both of said bell crank levers being pivotally supported on the shaft 43. The other arms of the bell crank levers l2 and M are connected by pitman and eccentric connections 15 with the main shaft 9.

It will be readily understood that as the cranks 62 and 63 oscillate the usual l-motion movement will be imparted to the feed dog 59, and that by reason of the connectionof the link 68 intermediately of the ends of the lever 66, each time the feed dog is engaged in the feeding of the fabric, the post 53 will be depressed slightly and the work clamp 46 relieved from tight engagement against the fabric and presser foot. The springs 55 associated with the work clamp 46 are independent of the plunger. As the feed dog comes up into contact with the material under the presser foot, the work clamp recedes, allowing the material to be fed through freely. When the feed dog has completed its feed travel and moves down, the springs 55 lift the work clamp against the material to hold it in position with enough pressure to allow the ridge forming element to stretch the material slightly as it rises to the needle penetration receiving position.

A ridge forming element or plunger 16 is vertically reciprocable through the opening 49 in the work clamp and the opening 2| in the foot for projecting a ridge or node of hem and body fabric into needle penetrating position. The ele-' ment i6 is provided with a needle accommodating notch TI and is adjustably supported on a cam slide or plunger 18 slide guided as at 19 in the work support extension 45 as shown in Figures 20 and 22.

The slide l8 includes a cam receiving cutout portion defined above by an elevation control shoulder 6| and below by a downward movement effecting shoulder 62. Operable in the cutout 36 is a 3-point wiper cam 83 which is secured at the left hand end of a. shaft 84 rockably supported beneath the work support or table 6E. The cam 83 includes a lifting surface 85 terminating in a nose 86 merging with a con.- centric dwell portion 61 and downward movement effecting surface 88. See Figures 3, 1-3, 16 and 20.

At its other end the shaft 84 is equipped with a crank 89 which is link-connected as at 90 to. one end of a lever 9i rockably pivoted intermediate its ends on a shiftable pivot pintle 92. The shiftable pintle is in the nature of a reduced end extending eccentrically from a stud shaft 93 rockably supported at 94 beneath the work support ll and having av shifter crank or lever 95 secured thereto. The crank 95 includes a handle portion 96 projecting above the work support 4i through a suitable aperture therein and adapted for association with an indicator scale 91 mounted on said support. A spring pin 98 carried by the work support 4| cooperates with notches 99 in the crank 95 for yieldably securing said clamp in its positions of adjustment. See Figures 6, 12, l4, l5 and 17.

The other end of the lever 9! is connected'by toggle links I06 pivoted together as at Hll 'to one arm of a bell crank I02, the other arm of the bell crank being pitman connected as at I63 with an eccentric Hi4 mounted on the main shaft 9. See Figures 4, 6 and 12.

A crank disc I65 mounted on a sleeve hub N16 is rotatably supported in the frame bearing I01 and has a crank pin Hi8 projecting therefrom in spaced relation to the axis of rotation thereof. The crank pin is link-connected as at I69 to the pivotal connection ID! of the toggle links I00 so that upon rotation of the disc H15 the toggle links will be alternately broken and straightened out. See Figures 9 and 18.

A small gear H0 and a larger gear lllare mounted side by side on the main shaft 9 and respectively mesh constantly with the large and smaller gears H2 and H3 secured on the hub sleeves I I4 and I I5 rotatably nested on the sleeve hub I66 as shown in Figure 9. The ratio of the gears is such that for each two revolutions of the main shaft 9 the sleeve hub H5 will be rotated once and for each four revolutions of said main shaft the sleeve hub H4 will be rotated once.

The sleeve hub H4 is equipped with a looking or clutching notch H6 and the hub H5 is equipped with a looking or clutching notch Ill.

In order to provide for eifectively'coupling one or the other of the hub and gear combinations I I2, H4, or H3, H5, I provide a shuttle pin IIB which is equipped with a cam end II9 projecting from the end of the sleeve hub I06, said pin being opposed at its inner end by a spring I20 which constantly tends to project the pin from the sleeve bore in which it is mounted. A clutch pin I2I projects radially from the shuttle pin and a shifter lever I22 shown in detail in Figure 10 is pivoted at I23 to the frame standard between limiting pins I24 and provided with a cam surface I25 for engaging the projecting end of the pin II8 to cooperate with the spring I20 for shifting the clutch pin I2I into locking engagement in one or the other of the notches H6 and H1.

It is my purpose in devising the present machine to enable the making of (1) a succession of anchor stitches passing through both the hem and the body fabric being worked upon, or (2) a plurality of such anchor stitches at the beginning and end of the formation of the hem with alternate skip and anchor stitches intervening the end sets of anchor stitches, or (3) a plurality of such anchor stitches at the beginning and end of the hem operation with intervening anchor stitches formed only at each fourth needle operation, there being between each pair of such intervening anchor stitches three skip stitches which pass through the turnedover or hem fabric only and not through both the hem fabric and the body fabric. These operations are made possible by employment of the shiftable pivot pintle 92 and the toggle link and selective gear ratio equipments illustrated in Figures 9, 12, 15 and 18. Although I have shown and described my invention as being particularly adapted in seaming hems, it will be understood that the machine may be employed in other sewing operations wherein a line of successive anchor stitches may be formed, or a line of alternate anchor and skip stitches may be formed, or a line of spaced anchor stitches with three skip stitches therebetween may be formed.

It should be understood that each time the cam nose 86 advances far enough to render any portion of the concentric or dwell cam portion 86 effective, the plunger I6 will have been elevated to a point for projecting a ridge of the hem and body fabric through the opening 2I of the foot into needle penetrating position whereby the needle 24 will penetrate the hem fabric and also the body fabric to form a resultant anchor stitch. When the plunger I6 is elevated to a lesser degree the needle will penetrate the hem fabric only, to form a resultant skip stitch which does not pass through the body fabric. Whenever the lever 95 is shifted to the position shown in Figures 15 and 18 the pivot pintle 92 will have been retracted causing a slight counterclockwise movement of the shaft 84 as viewed in Figures 15 and 18. The maximum cam advancement movement or lifting of the plunger I6 is accomplished when the toggle links I00 are broken to the maximum degree as illustrated in Figures 12, 15 and 18 and when the cooperating eccentric and strap connectionsIM, I03 are at the maximum throw position illustrated in these figures, these conditions serving to bring about a maximum of movement of the link 90 toward the left as viewed in Figures 12, 15 and 18;

In other Words, the maximum lift of the element I6 necessary in the formation of an anchor stitch ordinarily is accomplished'only when the maximum throw of the eccentric and strap connection I04, I03 and the maximum lift of the crank pin I08 and link I09 coincide. Thus when the shuttle pin I I8 is shifted to the position shown in Figure 9 causing the large gear I I2 and smaller gear IIO to be effective, the maximum eccentric throw and link lift illustrated in Figure 15 will occur only once during each four revolutions of the main shaft 9. During the intervening revolutions of the main shaft 9 the plunger I6 will be only partially lifted and will result in the needle penetrating the hem fabric alone and therefore three skip stitches will be formed between each spaced pair of anchor stitches.

When the shuttle pin I I8 is shifted to the right as viewed in Figure 9 so as to render effective the gears III, H3, the maximum eccentric throw and link lift will coincide once during each two revolutions of the main shaft and consequently maximum lift will be imparted to the plunger I6 at alternate revolutions of the main shaft and during the intervening alternate revolutions the element will be only partially lifted resulting in the formation of alternate anchor and skip stitches.

Whenever it is desired to form a succession of anchor stitches, it is only necessary to shift the lever 95 to the position illustrated in Figure 12 of the drawings at which time the pivot pintle 92 will be projected toward the left causing the link 90 to rotate the shaft 84 a slight bit in the clockwise direction thus slightly advancing the cam 83. In this adjustment regardless of the driving ratio of the gears selected at the moment, the ridge forming element I6 will be lifted the maximum degree at every revolution of the main shaft 9. This is possible because the shifting of the pivot pintle 92 brings about an overthrow of the cam 83 as shown in Figure 13 at the intervals, during which the maximum throw of the eccentric and pitman connection I04, I03 and lift of the link I09, coincide, and during each intervening revolution of the main shaft the movement of the cam 83, while less than the maximum, will still be sufficient to bring the dwell surface 8! into effect causing the necessary maximum lift of the plunger element I6. Thus it should be clear that with the lever 95 adjusted to the position illustrated in Figure 12, the element I6 will be lifted the maximum degree at each revolution of the main shaft 9 regardless of the gear ratio effective at the time thus causing the needle and complemental stitch forming mechanism to form a succession of anchor stitches which engage both the hem and the body fabric.

As illustrated in Figure 39 a plurality of anchor stitches may be formed at the beginning of the hem and then the lever 95 may be shifted to the position illustrated in Figure 18 and a series of alternate skip and anchor stitches made, after which the lever may be returned to its initial position and the hem operation concluded by a progression of anchor stitches. It will be observed that in the formation of the hem in Figure 39 the l-to-2 ratio gear unit III, H3 is employed.

In Figure 40 I have shown a fragment of a hem in which three skip stitches are formed intervening each pair of anchor stitches. In the formation of this seam, the lever 95 is shifted to the position illustrated in Figure 12 and a plurality of anchor stitches formed, after which the lever is shifted to the position shown in Figure 15 and with the 1-to-4 ratio gear unit IIO, I I2 in use the operation is continued forming three skip stitches in advance of each anchor stitch, and at the end of the hem the lever 95 may be shifted back to the original position and without any change of gear ratio the hem may be concluded by the formation of a succession of anchor stitches.

A lug I26 depends from the work support M and to this lug a latch dog I21 is pivoted as at I28. The dog I21 includes an eccentric lock-sur- 'face I 29 and a release lug extension I30. The lock surface I29 normally rests on one horizontal leg I3I of a bell crank lever pivoted at I32 on the frame lug I33, the remaining leg I34 of the bell crank extending downwardly and engaging a strong cushioned spring I35 seated in a frame socket I36. The contact between the leg I34 and the spring I35 is made by an adjustable abutment screwI31.

By reason of .the direct contact between the parts I29, I3I, I31, I35 downward movement of the work support M is strongly resisted by the spring I35 and the tendency of the spring I35 to force the support upwardly is suitably resisted by an adjustable stop screw I38 threaded through the guard wall 44 and abutting a'stop I39 se-' cured on the frame standard. By provision of this equipment a downwardly yieldable work support is provided and yet the spring I35 is much too strong to permit undesirable downward movement thereof.

When it is desired to lower the support M to insert or remove the work, the operator should not be subjected to the severe labor and strain necessary to oppose the relatively stronger spring I35 and for this reason I haveprovided a relatively lighter spring and means whereby the strong spring may be rendered ineffective and the weaker spring brought into play simultaneously with the effort of lowering the support.

It will be observed by reference to Figure 11 that a coil spring I40 connected to the support M and the dog I21 serves normally to retain the dog in the position illustrated in Figure 11. The relatively weaker spring above referred tois in the nature of a coil spring I4I coiled about the stud I42 projecting from the frame lug I33 and. having one end thereof anchored as at I43 to the frame and the other end I44 engaging under the work support M as shown in Figure 11. A trip lever I45 is pivoted intermediate its ends as at I46 to a lug depending from the support 4|. One end of the lever projects under the release lug I30 and to the remaining end a pull chain I41 is secured. By pulling downwardly on the chain I41 the dog I21 will be tripped to the position illustrated in dotted lines in Figure 11, thus releasing the support 4| from the influence of the relatively stronger spring I35 and permitting the operator-to lower the support by use of the chain I41 resisted only by the relatively weaker spring I4I. Upon release of the chain the spring I40 will return the dog' I31 to the position illustrated in full lines in Figure 11, the eccentric surface I29 facilitating the return to normal engagement with the bell crank leg I3I.

The strong spring I35 is essential to the attainment of even needle penetrations because the needle travels in a fixed path and consequently the same depth of the ridge of material must be always presented to the needle. Thus in the formation of anchor stitches it is necessary that the ridge forming element rise to the same high position in relation to the needle, and the work support which carries the element must be substantially rigid when heavy seams are encountered. The resistance to upward movement of the element must not be solid, however, because if the element could not push the material up through the opening in the presser foot something must yield or break. The spring I35 provides the desirable strong yet yieldable resistance.

When the operator desires to insert work, a slight pull on the chain I41 will release the toggle I45, I21. With the parts in this position the light spring I4I alone is effective to hold the work support against depression and only a slightforce is necessary to be exerted by the operator to depress the work support 4I sufficiently for inserting the work under the presser foot, or removing work therefrom. In this manner the depression of the work support or table 4I may be said to be opposed by a primary means and a secondary means of varying degree, and that said means may be rendered selectively effective.

A safety stop screw I48 may be provided to supplement the function of the stop screw I38 and assure against the exerting of excessive pressure contact between the work clamp and presser foot at any time.

The usual thread tensioning means is indicated at I 49 and includes the usual opposed tensioning plates or discs I50. In order to automatically release the thread tension whenever the work table or support M is depressed, I provide a release lever I5I which is pivoted at I52 on the machine frame. The lever includes a crank arm I53 which overlies the guard wall or flange 44 of the support and is equipped with an adjustable abutment screw I54 for engaging said wall. The lever also includes a releasearm I55 which projects into position for engaging between the tension plates I50. A coil spring I56 encircles the lever and has its end extended for engagement with the frame release arm I55 for holding the abutment screw I54 in engagement with the support wall 44. Each time the support is depressed as shown in dotted lines in Figure 24 V of the drawings, the release arm I55 will effect a separation of the tension plates I 50.

It is desirable to seam a hem with the cross stitch formation as shown in Figures 34 to 36, 39 and 40. In order to make this cross stitch, it is necessary to take the thread from a position above the hem on the right hand side and lay it in the form of a loop in a position under the needle point on the left hand side of the hem where the needle point penetrates the loop as shown in Figures 34 to 36. A novel form of thread looper is employed for this purpose. To this end a bracket member I51 is secured as at I58 to the presser foot 20 and a pivot block I59 is pivotally supported as at I60 to swing about a vertical axis on said bracket. The block is cross-grooved to receive a thread looper IBI, said looper being pivoted intermediate its ends as at I62 in the groove to swing about a horizontal axis. At one end the looper carries a cam block I63 provided in its under surface with a guiding cam surface I64 adapted during horizontal swinging movements of the looper to ride over a roller I65 journaled on the bracket member I51 and at its other end the looper rides over a stationary ridge cam I66 secured as at I61 on the presser foot 20. At its end beyond the ridge cam I66 the looper I6I terminates in an integral downturned front finger I68 and also carries a cooperating .similiarly shaped rear finger I69 yielda

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