US3020865A

US3020865A - Sewing machine for producing variable stitches

Info

Publication number: US3020865A
Application number: US549785A
Authority: US
Inventors: Forster Jakob; Grunke Erich
Original assignee: FORSTER GEB
Current assignee: FORSTER GEB; Gebr Forster
Priority date: 1954-11-30
Filing date: 1955-11-29
Publication date: 1962-02-13
Anticipated expiration: 1979-02-13
Also published as: DE1049676B; CH338348A; BE543000A; FR1139752A; CH327236A; US3089444A

Description

Feb. 13, 1962 SEWI Filed Nov. 29, 1955 J. FORSTER ETAL 3,020,865 NG MACHINE FOR PRODUCING VARIABLE STITCHES '7 Sheets-Sheet 1 INVQVTORS Jaws l'FmrrR 571 716701111 Feb. 13, 1962 SEWING Filed NOV. 29, 1955 J. FORSTER ETAL 3,020,865

MACHINE FOR PRODUCING VARIABLE STITCHES 7 Sheets-Sheet 2 3o as 1 5 ,9 a2

33 23 Z 50 F 26 as 47 45 27 2a 25 I 39 z I! 1 0 L /o 1 ll 2 i /Z 22 2 I3 I; 5 4 37 75 I 6 4 33 W 41 1c Z 44 I7 2 r hz wv h Feb. 13,1962 J. FORSTER ElAL 3,020,865

SEWING MACHINE FOR PRODUCING VARIABLE STITCHES Filed Nov. 29, 1955 '7 Sheets-Sheet s V 3 Z 4 l k l\ K I \Q Q Ygfil a f I I I I V M/l/[A/TOIFS Java/57:22? [ha/Gram? Feb. 13, 1962 J. FORSTER ETAL 3,020,865

SEWING MACHINE FOR PRODUCING VARIABLE STITCHES Filed Nov. 29, 1955 7 Sheets-Sheet 4 [fills/Wok; JAKOBEA'JCER Ear/16 3 Mark Feb. 13, 1962 3,020,865

SEWING MACHINE FOR PRODUCING VARIABLE STITCHES Filed Nov. 29, 1955 J. FORSTER ET AL '7 Sheets-Sheet 5 INVfNIOIU \hms/a'imrm Earl! 6WNKE BY A, M 1% Feb. 13, 1962 J. FORSTER ETAL- 3,020,865

SEWING MACHINE FOR PRODUCING VARIABLE VSTITCHES Filed Nov. 29,- 1955 I 7 Sheets-Sheet s Ill I25 I20 I21 DIVE/V7065. Jaws Ewan-R 1571c GRl/NkE ZZMM Feb. 13, 1962 J. FORSTER ETAL 3,020,865

SEWING MACHINE FOR PRODUCING VARIABLE STITCHES Filed Nov. 29, 1955 7 Sheets-Sheet '7 2 24 m u 1 Minimum INV EN TORS' @(aa fmesrae By [re/c 6'2 (IA/ME 3,020,865 SEWING MACHINE FGR PRODUCING VABLE STlTCHES Jakob Forster and Erich Griinlre, Hinwil, Switzerland, assignors to Gehr. Forster, Hinwil, Switzerland, a firm Filed Nov. 29, 1955, Ser. No. 549,785 Claims priority, application Switzerland Nov. 30, 1954 1 Claim. (Cl. 112-159) The invention relates to a sewing machine for producing variable stitches, having at least one stitch-forming element (needle, loop taker) moveable transversely of the direction of movement of the fabric to be sewn, to which element an oscillation of variable amplitude from centre position can be imparted.

In the known sewing machines of this kind, the maximum amplitude of the oscillation, which amounts for example to 2-5 millimetres, can only be utilized when the centre of this oscillation is in the middle of the field of operation. Accordingly the stitch patterns of the kind illustrated in FIG. 1 may be produced, the width of the field of operation amounting here to 4-5 millimetres.

The object of the present invention is to increase the stitch characteristics and especially the formation of stitches. This is attained according to the invention by providing a sewing machine that comprises means which permit the utilization of the maximum amplitude of the oscillation even when the centre of oscillations is displaced from the middle of the field of operations.

The width of the field of operation may for example amount according to FIG. 2 to a +2a =9 millimetres, wherein a is the distance of the two extreme positions of the centre of oscillations, and a is the maximum amplitude of oscillations of the. stitch forming members which may amount for example to 2.25 millimetres. In the case of FIG. 2 has been selected equal to 211 because this is favourable for certain operations. The variation of the width of stitches as well as the displacement of the stitches is effected steplessly inall practical embodiments of the machine. Of course the width of the field of operation need not be fully employed during use, and one may operate in a narrower range than that available, if desired, owing to the design of the machine. Preferably the Width of the field of operation amounts to at least 9 millimetres.

In certain known sewing machines both stitch forming elements, i.e. needle and loop taker, perform the same oscillation of variable amplitude and centre position. This is the case in the embodiment of the invention described by Way of example with reference to FIGS. 3 to 12, whereas in the embodiment illustrated by way of example in FIG. 13 this oscillation is performed by the needle only.

Another important object of the present invention is to provide means conducive to a positive control of the stitch patterns as to their length, width, field and similar characteristics.

These and other objects of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawings showing preferred embodiments of the invention.

In the accompanying drawings:

FIG. 1 shows the pattern of stitches as it may be produced with the usual sewing machines.

FIG. 2 shows a stitch pattern capable of being produced by means of the sewing machine according to FIGS. 3 to 12.

FIG. 3 is a front elevation of a sewing machine embodying the invention, the machine being depicted partly broken away and partly in section, to expose to view ice the main drive of the machine, and the drive for producing the lateral amplitude of the stitch forming elements. 1

FIG. 4 is a fragmentary cross section taken on line 33 of FIG. 3 and drawn on a larger scale.

FIG. 5 is a part-cross section taken on line 4-4 of FIG. 4.

FIGS. 6 to 8 show diagrammatically respective variations of amplitude and centre positions during oscillation.

FIGS. 9 and 10 show a loop taker assembly in elevation and section.

FIGS. 11 and 12 show another loop taker assembly in two sections.

FIGS. 13a and 13b, taken together, show a diagram matic side elevation of the components most essential in connection with a second embodiment of the invention.

FIG. 14 is an exploded view of the bifurcated lever and associated displacement mechanism.

According to a preferred embodiment of the invention there is disclosed a housing 1, which accommodates a shaft 2 which is set in rotary motion by a wheel 3. The shaft 2 comprises a cam 4 which rotates with said shaft, and sets a rocker 5 into a uniformly oscillating motion about a pivot axis 0. The rocker 5 carries at its extreme rocking end a slider block 7 rotatably mounted on a pin 6, which block likewise is made to oscillate and is embraced laterally by a forked guide 8 of the bifuracted lever 9 (FIG. 3).

An arcuate guide 10 (FIG. 4) provides for the guiding of a segment-shaped slider block 11 which through a guide pin 12 connects the slider block 11 and the bifurcated lever 9 While providing a limited freedom for horizontal rotation. The bifurcated lever 9 is secured in its strictly horizontally moveable position by means of a guide 13. By displacing the slider block 11 in the guide 10, the position of the bifurcated lever 9 is varied in such a manner that by the oscillation of the slider block 7 in the forked guide 8, the bifurcated lever 9 is set into an oscillating horizontal motion about the guide pin 12 which motion may be increased, or reduced to zero amplitude. A pin 14 partakes in the motion described hereinbefore, and performs in this manner a variable adjustable amplitude.

A guide head 15 is moveably mounted on the guide pin 12, and can be displaced by means of a crank 16 through a control shaft 17 having a knob 18 to be operated from outside, whereby the pin 12 with the slider block 11 and accordingly the pivot point of the bifurcated lever 9 is displaced.

The purpose of the mechanism described is that the pin 14 of the bifurcated lever 9 may: be set in an oscillating motion of an amplitude which is variable at will, forming the basic motion for the width of the sewing stitches which can be displaced as will be described hereinafter and described summarily with reference to FIGS. 6 to 8.

On the pin 14, a second lever 19 is mounted which is also horizontally tiltable and which partakes in the movement of; the bifurcated lever 9 and of the pin 14. The lever 19 is articulated at one end to the lever 22 by means ofa joint 20 and connecting link 21, and this lever is in turn articulated to the vertical shaft 23. The vertical shaft 23 serves, as a means for the transmission of the movements generated by the bifurcated lever 9 and the displacement lever 19 on to the stitch forming members, namely the needle and the loop taker. The joint 24, of the lever 19 serves for the mounting of a moveable head 25 the position of which is controlled from the knob 26 through the control shaft 27, the control lever 23 and the slider block 29. By the movement of the head 25 the lever 19 is turned about the pin 14,

whereby a displacement of the components 20 to 22 is effected. This displacement has the effect of turning the vertical shaft 23 in one direction or the other while the pin 14 is in a rest position. The said vertical shaft 23 is set into corresponding oscillations about the rest position when the pin 24 oscillates, the position of the center of its oscillations is adjustable by means of the knob 26, while their amplitude can be adjusted by means of the knob 18 as explained hereinabove.

FIGS. 6 to 8 illustrate once more diagrammatically how the oscillations of the vertical shaft 23 are brought about:

According to FIG. 6 the slider block 7 rocks at .a constant amplitude in the direction of the double arrow. The slider block 7 imparts to the lever 9 by means of the forked guide 8, an oscillation the extreme positions of which are indicated in dotted lines and the amplitude of which depends on the pin 12. The pin 14 mounted on the lever 9 carries along the lever 19, the pivot point 24 of which is adjustable by means of the control shaft 27. In FIG. 6 the pivot point 24 is in its middle position, in FIG. 7 it is displaced to the left, and in FIG. 8 to the right. The oscillation transmitted by the pin 14 on to the lever 19 is transmitted by the

elements

21 and 22 to the vertical shaft 23. In FIG. 7 the center of the oscillations of the vertical shaft 23 and lever 22, respectively, is displaced to the right, in FIG. 8 to the left. The center position is shown in full lines, while the extreme positions are indicated in dotted lines.

The vertical shaft 23 carries at each of its ends levers 30 and 31, respectively, which partakes at any time in the displacement of the vertical shaft 23. The angular deflections of the

levers

30 and 31 thus produced olfer possibilities for the articulation of the stitch forming members, which then together generate sewing stitch patterns transversely of the direction of sewing. The knob 18, when operated determines the width of the stitch, whereas the displacement of the stitches is determined by the knob 26. In order to be able to use an automatic control alternatively to the manual operation of the

knobs

18 and 26, the drive of a control spindle 33 is effected through a worm wheel 32, on which spindle the control cams A and B required-two not shown in the drawingare mounted. On one of these control cams A rests the cam follower lever 36 which positively transmits its movement prescribed by the control cam through a slider block 37 to a projection of a knob 18 a compression spring 4-4 is mounted which secures the knob 18, which is rotatable about a pin 45, in a rest 42 of the rest ring 43. When now the manual control is to be started from this position, the knob 18 is gripped and lifted out of its rest by slightly turning the same, whereafter the said knob becomes freely rotatable.

The control movement of the knob 26 for the alternative manual or automatic control of the lever 19 for the displacement of the sewing stitches is effected in a manner similar to the control described hereinbefore. The bore of the control lever 28 is provided with a key way. The control shaft 27 is provided with a key 47 which couples the control lever 28 to the control shaft 27.

sleeve 38. The longitudinal bore of this sleeve 38 serves as a bearing for the aforesaid control shaft 27 when the knob 18 is operated by hand. For the automatic control, the sleeve 38 is provided with a clutch which permits coupling the same to the control shaft 17. For

"this purpose a key way 39 may be provided in the bore of the sleeve 38. The control shaft 17 is provided with a coupling key 40. When the automatically controlled transmission is to be operated by means of the cam disc, the knob 18 with its control shaft 17 and the key 40 are moved in the bore of the sleeve 38 in the direction of the arrow, until the key is inserted into the key way 39 of the sleeve 38 and the control shaft 17 with its fixedly mounted components is made to partake likewise in the movements of the projection of sleeve 38. In this position a detent (not shown), for example a spring biased ball, engages a rest groove 41 of the control shaft 17, in order to secure the latter against unintentional displacements. When it is, however, desired to interrupt the automatic control, the knob 18 is moved on a control path in the direction opposite to the arrow. Then the aforesaid detent engages a second rest groove and thereby secures the control shaft 17 in a position in which the key 40 no longer engages the key way 39, and the sleeve 38 is therefore declutched from the control shaft 17. The knob 18 is then engaged with a locking nose in a rest ring 43, and is in this manner restrained from rotating. In the grip portion of the The control cam follower lever 48 is mounted on the control shaft 27 ahead of the control lever 28 and is provided with a key way 49. The cam follower lever 48 receives its motion from a second control cam B adapted to be pushed over the shaft 33.

By moving the knob 26 and control shaft 27 in the direction of the arrow until a detent 50 engages a rest groove 51 provided for this purpose, the key 47 partly enters into the key way 49, and thereby rigidly couples the control lever 28 with the cam follower lever 48 so that the movement of the control lever 28 is effected by the associated control cam. When now the rigid connection is to be disconnected and the operation of the lever 19 for the displacement of the sewing stitches is to be effected by hand, the knob 26 with the control shaft 27 and the key 47 are moved in the direction opposite to that of the arrow, whereby the key way 49 of the cam follower lever 48 is cleared again. Alternatively one may for example make the control cam effective for the amplitude only, and control the displacement of the stitches by hand, or conversely effect only the displacement of the stitches automatically and control their width by hand.

The operation described above of the aggregates for the width of the sewing stitches as well as for the displacement of the stitches permits a manual control, at will, an automatic control and a combined control, whereby numerous variations of the stitches can be attained in a convenient manner.

From FIGS. 3 and 4 it can be seen how the articulation of the stitch-forming elements to the vertical shaft 23 is effected by means of the

levers

30 and 31. The pull rod 52 is connected on one end to the bearing 53 of a pin 54 which engages an eye of the lever 30 mounted on the vertical shaft 23. The pull rod 52 has on the other end an articulated connection to the frame 55 which takes in the needle bar 56. A chuck 57 secures the needle 58 in its position. The transmission of motion to the loop taker is effected in a similar manner. The

lever 31 mounted on the vertical. shaft has a bifurcated aperture wherein two mutually opposite slider blocks 59 are rotatably mounted on two guide pins 60. The slider blocks 59 engage a guide sleeve 62 fixedly mounted on the driving shaft 61 of the loop taker and in this manner let the driving shaft 61 with the loop taker 63 fixedly connected to it partake in its motion. Since the choice of the loop taker system can be adapted to the actual requirements, three loop taker systems of different kind are illustrated in FIG. 3.

According to FIG. 3, the main drive of the sewing machine comprises various spur gears, namely a spur gear 64 fixedly mounted on the shaft 2 which is driven by the hand wheel 3. From there the transmission is effected to the main shaft 65 and to the shaft 61 of the loop taker. The spur gear 67 serves merely as an intermediate gear for the transmission between the spur gear 64 and 68. The spur gear 68 fixedly connected to the worm 69 sets the latter forcibly in rotation. The worm 69 drives the worm wheel 32. The spur gear 70 serves for driving the loop taker shaft 61. The non-circular bore of this spur gear is adapted to the cross section profile of the loop taker shaft in order to carry the latter along in rotation, and serves at the same time as a guide for the longitudinal movements thereof.

The support bracket 71 serves as an intermediate hearing for the shaft 2, and for receiving the carrier pin 72 of the rocker arm 5. The knob 73 with the rest ring 74 is provided for the operation of the lever (not shown in the drawing) controlling the length of the stitches.

FIGS. 9 and show respectively a loop taker assembly withthe axis of the loop taker lying in the direction of sewing.

The rotary driving shaft 77 which like the shaft 61 of FIG. 3 forcibly partakes in the control movement of the needle bar, makes the entire loop taker assembly partake in this motion.

The bearing 75 of the axle 87" of the loop taker 86 is attached to the guide pins 76 which are moveable in guide sleeves mounted in the base of the sewing machine. A couple of helical gears 79 transmits the rotary motion from the driving shaft 77 onto the axle of the' loop taker 86. A flap 81' with a holder spring 82 are likewise connected to the moveable bearing 75.

The components '75, 76, 79, 81, 82 and 86 are connected to the driving shaft 77 by means of the block 83, this block 83 being secured laterally in its position by two adjustable collars 85 arranged on the driving shaft 77, and consequently being forced to followthe to-and-fro movements of the shaft 77. The block 83 has a bearing 84 in" which the shaft 77 performs its rotary motion.

To the FIGS. 11 and 12, in which the components and their motions correspond to those of FIGS. 9 and 10', the same description applies as to those figures. The only difference is that the loop taker 86, which otherwise is In order to be able to shift the casing 102 to-and-fro in the sense of the double arrow 103 the same is articulated at 115 to the top end of bar 116 which extends substanti'ally in the vertical direction, and at half the height of which a horizontal pin 117 is rigidly mounted, which is guided for horizontal movement in a guide 118 provided on the machine casing 100. The bar 116 is articulated at 111? on a coupling member 120, which is in turn articulated at 121 to a rocker arm 123 pivoted about the fixed fulcrum 122. This rocker arm carries a feeler 124 which contacts the control earn 125. When, under the action of a spring (not shown), the feeler 124 follows the control cam 125, the coupling link 120 performs a horizontal movement in the direction of the double arrow 126 which is transmitted to the casing 102 of the mechanism and accordingly to the support point 107 of the needle bar guide 108 whereby the centre of the zig-zag oscillation is displaced. The amplitude of the oscillation is independent of this displacement of the centre, any desired amplitude being capable of being adjusted to any position of the centre of oscillations, up to the maximum amplitude as determined by the known mechanism. The toand-fro movement is transmitted from the lower point of articulation 127 of the bar 116 also on to the loop taker 128 (diagrammatically indicated by a circle) which is accordingly displaced in the same manner as the centre of the zig-zag oscillation.

The bar 116 is articulated at 127 to a bushing 130 which is rotatably mounted on the gripper shaft 129 between two not shown in detail, has a vertical axis 87,. in both cases the axle of the loop taker stands at right angles to the driving shaft 77 instead of coinciding therewith as in FIG. 3. Such loop takers which for many operations are better suited than the loop taker 63 according to FIG. 3 have been made hitherto only stationary. The new loop taker assemblies according to FIGS. 9, 1'0 and 11, 12 respectively, are used with great advantage in the sewing machine described.

In the second embodiment to be described hereinafter the loop taker undergoes merely a translation c'orresponding to the actual centre position of the needle.

In the combined FIGS. 13a and 13b the outline of the casing is indicated in quite a diagrammatic way in chain dotted lines. Likewise in chain-dotted line's some components of the machine are indicated, the design and tune tion of which are well known in the art. These components which hereinafter are scarcely mentioned have been shown in order to facilitate the visualizing of the machine.

The main shaft 101 journalled in the usual manner in the machine casing 100 is moreover journalled' in a shiftable casing 102, which contains amechanism for generating the zig-zagging movement of the needle and a mechanism for producing a deflection of the needle to the right or to the left, both of which mechanisms are known in themselves and accordingly do not require a detailed explanation. What is novel is that the casing 102 containing these mechanisms can be moved to-and-fro according to the double arrowltld, which will be described in more detail hereinafter. A horizontal rod 104 fixedly connected to the shiftable casing 102lis guided in the machine casing 100 by means o fthe diagrammatically indicated bearings 105 and 106 On a transverse pin 107 fixed to the rod 104 a needle bar guide 108 is suspended til't'abiy 'in which the needle bar 109 can be moved up and down in the usual manner, the needle chuck "110, the heedle 111 and the fixing screw 112 for the latter partaking in this movement. On the lower portion of the needle bar guide 103 the end of the known zig-zag deflector rod 114 is articulated at 113, the other end of which receives its motion for the zigzag amplitude from a rocker component (not shown) which is arranged in the casing 102.

adjustable collars 131 fixed to said shaft 129. The gripper shaft 129 is journalled in the

bearings

132, 133 and 134 provided on the machine casing 100, and is driven by the gear wheels 135 and 136. The gear wheel 135 is mounted on a shaft 137 which is driven from the main shaft 101 by means of a transmission pulley 138 and a transmission belt 139.

The gear wheel 136 is mounted readily slidably 0n the key 140 which couples it for rotation with the gripper shaft, and when the shaft is shifted, this gear wheel is restrained from partaking in this shifting by abutments (not shown) designed as rollers.

The loop taker assembly corresponds substantially to that according to FIGS. 9 and 10. Its casing 141 is provided' with guide pins 142, 143 which are guided in

bearings

144, 145 provided in the machine casing 100. The guide pin 143 is screwed fast on the bracket 146, which is mounted on the shaft 129 between two adjustable collars 147 and accordingly takes part compulsorily in the lateral shifting of the shaft 129. The adjustable collars 147 are fixedly connected to the shaft 129 and partake in the rotary as well as in the reciprocating movement thereof.

From the foregoing description it is clear that the loop taker 128, the axle of which crosses the shaft 129 at right angles, and the needle 111 receive a common displacement derived from the control cam 125. Alternatively control cams may be provided for the control of the right hand side-left hand side mechanism and of the zig-zag mechanism as well as for the forward-and-backward stitch.

In the usual machines always the same number of stitches is required for the completion of an ornamental stitch pattern. Some recent attempts at overcoming this limitation have not been quite successful from the structural point of view. The machine illustrated on the other hand comprises a very convenient regulator for the length of the stitch pattern with which the pitch of the stitches does not vary with the length of the stitch pattern.

, Referring to FIG. 2 it will be noted that hollow shaft 148 (FIG. 13b) on which the control cam125, or a whole set of control cams, is mounted, a switching pin 149 is coaxially arranged which is pivotally mounted on the machine casing 100 and is fixedly connected to a lever 150 on which a connecting rod 151 is articulated. To this connecting rod 21 vertical up and down motion is imparted in a manner whereby the stroke thereofcan be freely selected within certain limits.

The switching pin 149 is provided at its circumference with three recesses152 designed as champing guides for rollers, wherein for example three clamping. rollers 153 are arranged. When the pin 149 is turned in the anticlockwise direction, the clamping rollers 153 jam between the wedge face 154 and the inner wall surface of the holw shaft 148 so that the latter is compelled to partake in the rotational movement of the pin. In the subsequent rotational movement of the pin in the clockwise direction the jamming is released in that the rollers come to lie freely rotatably on the surfaces 155 of the recesses 152. Upon an up and down movement of the connecting rod 151 accordingly the hollow shaft 148 and the set of control cams mounted thereon is turned onward stepwise and this the faster, the larger is the stroke.

It may be also mentioned that the stepwise feed of the set of control cams takes place at the moment when the needle is outside the fabric, whereas the return stroke of the parts or components 149 to 151 takes place in the moment when the needle is in the fabric for the formation of the stitch.

On the axle 156 a slider block 157 is mounted on which the guides 158 of the connecting rod 151 are guided. In the upper portion of the connecting rod 151a ring 159 is mounted having a spherical outer surface which is fitted on an eccentric 160 of variable effective eccentricity. The eccentric 160 has the shape of a circular cylinder the end face of which is inclined to its axis, and is fixedly connected to a flanged sleeve 161 which is slidably mounted on the main shaft 101 but is carried along by the same in rotation. A double lever 163 pivoted at 162 on the ma-, chine housing 101 has at its lower end (which is bifurcated in a manner not shown) two dogs 164, (only one stepwise by the pawl always inthe same direction when the lever 150 is turned to-and-fro, namely at any time one tooth, or two or more teeth, depending on the amplitude of the oscillation. The effect would be the same as with the regulator illustrated, the switching pin 149 and the;

clamping or clutch means 152-155 obviously being dispensed with.

While we have herein described and illustrated in the accompanying drawing considered typical and particularly useful examples of our said invention we wish it to be understood that we do not limit ourselves to the particular details and dimensions described and illustrated, for obvious modifications will occur to a person skilled in the art.

What we claim as our joint invention and desire to secure by Letters Patent, is:

In a zig-zag' type sewing machine having a vertically reciprocating needle bar for mounting and moving a needle at the lower end of said needle bar, a rotating loop taker disposed below and spaced from the lower end of the needle bar, a main drive shaft including transmissions connected to the needle bar and to the loop taker to operate the same in unison, a vertical shaft, a first displacement lever at the top portion of said vertical shaft, means connecting said first lever to the needle bar to control transverse movement thereof, a second displacement lever at the lower portion of said vertical shaft, means connecting the second lever tothe loop taker to control transverse movement thereof; the improved mechanism for controlling the transverse movement of i the needle bar and of the loop taker through said vertibeing shown) which engage an annular groove 165 from opposite sides of the sleeve 161. The upper arm of the lever 163 is designed as an adjustment dialsector 166 which is adjustable by hand with respect to fixed markings 167.

In the position illustrated the effective eccentricity of the eccentric 160, namely the eccentricity at the location of the ring 159, is very small. When the lever 163 is turned in anticlockwise direction, the eccentric is displaced to the right, on the main shaft 101, and thereby the effective eccentricity is increased which has the consequence of an increased stroke of the connecting rod and accordingly of a quicker rotation of the control cams.

Since the main shaft 101 is connected in a known manner (not shown) to the feeder device for the cloth the pitch of the stitches remains always constant, while the length of the decorative stitch pattern becomes larger, the slower the rotation ofthe control cams. Of course it is not absolutely necessary to effect the formation of the decorative pattern automatically with the aid of the control cams and alternatively, the control cams can be made inoperative in any wayfor example by adjustment of the feeler-so as to control the formation of decorative stitches manually. The decorative stitch patterns illustrated in FIGS. 14 and 15 show that, as in the first embodiment of FIGS. 28, the maximum amplitudea of the cal shaft comprising a first control member mounted for reciprocation, cam means mounted on said main drive shaft for reciprocating said first control member, a second control member mounted about a pivot for horizontal re.- ciprocation, said second control member having one portion thereof spaced from said pivot being connected to said first control member, another portion of said second control member spaced from said pivot being connected to said vertical shaft, means fOr displacing said pivot of said second control member so that the center points of the oscillating movement of the needle bar and of the loop taker are commensurately displaced, and means for automatically changing the amplitude of reciprocation of the first control member, driving gears on said main shaft, an'anxiliary cam shaft, speed reducing means connecting the auxiliary cam shaft to one of said gears connected to said main drive shaft, a first and a second cam mounted on said auxiliary cam shaft, first cam follower means connecting said first cam to said means for changing the amplitude of reciprocation of said first control member, second cam follower. means connecting said means for displacing said pivot of said second control member for displacing the center points of oscillation of the needle bar and loop taker whereby both of the amplitude and the center points of the oscillating movement of the needlebar and loop taker are displaced automatically in a predetermined manner,

References Cited in the file of this patent UNITED STATES PATENTS 2,003,879 De Spain June 4, 1935 2,045,340 Bolter June 23, 1936 2,579,248 Austlid Dec. 18, 1951 2,623,487 Marasco Dec. 30, 1952 2,653,557 Casas-Robert Sept. 29, 1953 2,684,649 Scarpa July 27, 1954 2,690,723 Hidenori Sudo Oct. 5, 1954 2,755,754 Urscheler July 24, 1956