US3580199A - Embroidery stitching sewing machine - Google Patents

Abstract

The disclosure relates to an embroidery stitching sewing machine in which a laterally oscillatable needle-bar can be selectively connected to any cam of a plurality of cams for providing zigzag and ornamental stitching, and in which a work fabric feeding device can be automatically controlled by cam means for providing a feeding sequence including forward and rearward steps. Said cam means comprise one cam of such cam track profile to provide a sequence comprising two steps forward and one step backward to produce a stitching wherein in any stitch pitch three sewing stitches are present, the cams of said plurality providing ornamental and utility embroidery and zigzag patterns compatible with said sequence.

Description

United States Patent [72] Inventor Luigi Vigorelli 80, Viale Partigiani, 27100 Pavia, Italy [21 Appl. No. 822,862

[22] Filed May 5,1969

[45] Patented May 25, 1971 [32] Priority May 8, 1968 [3 3 Italy [54] EMBROIDERY STITCHING SEWING MACHINE 8 Claims, 13 Drawing Figs.

[52] US. Cl 112/158, 1 12/102 [51] Int. Cl D05b 3/02 [50] Field ofSearch 112/98, 102, l 5 8 [56] References Cited UNITED STATES PATENTS 2,653,557 9/1953 Casas-Robert et 112/98 2,976,830 3/1961 Vigorelli 112/158 3,065,716 ll/1962 Vigorelli 112/158 3,221,687 12/1965 Hayashi et al. 112/158 3,253,559 5/1966 D'Amico 112/158 3,433,092 3/1969 I-Ianyu ll2/158X Primary ExaminerAlfred R. Guest Attorney-Michael S. Striker ing forward and rearward steps. Said cam means comprise one cam of such cam track profile to provide a sequence comprising two steps forward and one step backward to produce a stitching wherein in any stitch pitch three sewing stitches are present, the cams of said plurality providing ornamental and utility embroidery and zigzag patterns compatible with said sequence.

PATENTED HAY25 l97| SHEET UF 4 WIN WIN mg a INVENTOR.

EMBROIDERY STITCHING SEWING MACHINE BACKGROUND OF THE INVENTION This invention relates to sewing machines, and more particularly to sewing machines capable of selectively producing automatically a wide variety of utility and ornamental embroidery stitch patterns.

More detailedly, this invention concerns the art of sewing machine comprising a laterally oscillatable needle-bar, cam means for oscillating said needle-bar according a predetermined cycle comprising a rather large plurality of stitches, such as stitches, a feeding mechanism for progressing the work fabric in longitudinal direction on a machine worktable and cam driven means for actuating said feeding mechanism so that rearward feeding of work fabric steps are included in a feeding cycle comprising a greater number of forward feeding steps. Such machines can also comprise a slide plate forming a part of said work plate, laterally shiftable together with the work fabric progressing feed-dog means, and cam means for reciprocating said slide plate and feed-dog transversally to the direction of progression of said work fabric.

A number of machines as above have been proposed and produced. In the U.S. Pat. No. 2,976,830 issued on Mar. 28, 1961 to late Arnaldo Vigorelli, there had been described an ornamental stitch sewing machine including the above features, and wherein the needle-bar oscillating means comprise a plurality of coaxial carns each one of which could individually and selectively be engaged by one cam follower for selection of the automatically produced zigzag and embroidery pattern.

In my U.S. Pat. No. 3,065,716 another machine of the above considered type has been described as comprising coaxial needle-bar oscillating cam means, feed-dog driving cam means and slide plate shifting cam means, together with movement amplitude adjusting means and various features.

Broadly speaking, such and other prior art machines have been proved to be subject to certain objections and disadvantages. Such machines are of complicated and therefore costly manufacture, require careful handling and constant maintenance, as proper indexing and phase of the great number of components is to be carefully maintained. Such machines have an exceptional flexibility to the most various embroidery stitching because they are provided with adjusting means. Thus, in the prior machines there are comprised operator-controllable means for varying the zigzag stitching width, the slide plate shifting amplitude, the mean line of stitching relatively to the middle of needle-bar oscillation, and so on, in addition to conventional adjustment of the work fabric feeding pace, that is of the stitching longitudinal pitch.

While it is fully acknowledged that the ability of producing a substantially infinite variety of ornamental embroidery patterns, by the use of a number of such prior art machine, is still unsurpassed, such machines cannot provide certain stitchings in demand, such as expansible stitching, that is stitches which can adapt themselves to a substantially large stretching of the work fabric, namely of knitted fabrics, of fabrics woven with resilient polyamide or other synthetic filamentary material, and the like.

In addition, such machines require a very skilled operator for properly and safely operating same. A not proper action on the numerous control means can spoil the work and even cause damage to the mechanisms. In general, a part and even a small part only of the abilities of such over capable machines are enjoyed and actually made use of by the most of operators, in particular by housewives part.

Upon a consideration of the above and other factors, I have found that a number of modes of producing embroidery stitching are essential and critical for profitably making use of such machines, while a great number of potential abilities are actually superfluous and undesired, and while other stitches, namely the expansible" ones, are on the contrary desirable. Further, I have found that a fully automatized embroidery stitching sewing machine would be very desirable if of drastically simplified construction and operation.

SUMMARY OF THE INVENTION It is therefore an object of this invention to provide a new and improved machine as above defined, and which comprises a plurality of coaxial cams each adapted for cooperation with one cam follower drivingly connected to the needle-bar oscillating support means and each of such cam track to impart to said needle-bar a cycle of oscillation providing an embroidery pattern, different from the patterns provided by other cams, a first cam follower shiftably supported for selective engagement with any of said cams, and operator-controlled means for selectively shifting said first cam follower, the improvement comprising a second cam follower, drivingly connected to the machine's feeding mechanism control means, detachably engageable with a cam track with which one feeding controlling cam is provided, said latter cam track being such to impart to the feed-dog means a sequence of motions causing the work fabric to move forward for a given plurality of steps and then move backward for number of steps corresponding to that of such plurality minus one.

The most preferred sequence is two steps forwardone step backward, and the said feeding controlling cam has a cam track such to provide such sequence.

According to a most preferred feature of the invention, said feeding controlling cams is one component of said plurality of coaxial cam and it is selectively engageable by the said first cam follower also.

The machine can be also provided with a slide plate for lateral reciprocation of the feed-dog means, a third cam follower connected to said slide plate, and a particular cam not forming part of said plurality for engagement with said third cam follower.

According to another aspect of the invention, the first-cam follower is mechanically linked to the needle-bar oscillatable support to impart to said support a lateral reciprocation the amplitude of which is a function solely of the cam track profile of the cam actually engaged by the said first cam follower, no adjusting means being provided for adjusting said amplitude. As a matter of fact, I have found that ornamental embroidery stitchings are actually produced only at the greatest width that the sewing machine can provide and that, therefore, a relevant structural simplification and a safer operation can provided by unadjustably linking said first cam follower to said oscillatable support.

According to a further aspect of the invention, the greatest part or preferably all cams comprised in said plurality are provided with cam tracks of such profile to provide a first attractive ornamental or a utility stitching pattern when the sole needle-bar oscillating means are activated, and a second quite different ornamental or utility stitching pattern is also provided when both needlebar oscillating means and the work fabric feeding control means are activated, whereby the number of stitch patterns selectively available is twice that of cam comprised in the said plurality, the said aspect of the invention being dependent from a compatibility of the cam track profiles with the said sequence of stepped forward and backward motions.

These and other useful objects, advantages and features of the invention will be apparent from the following detailed disclosure of a preferred embodiment thereof, as shown in the accompanying drawings, forming and essential component of this disclosure.

THE VIEWS OF THE DRAWINGS FIG. 1 is a perspective diagrammatical illustration of the machine, having parts broken away for showing the essential components and mechanisms thereof;

FIG. 2 is a fragmentary perspective view of same machine, for illustration of its simplified control means;

FIG. 3 is partly a side view and partly a sectional view, taken substantially along line III-IIIIIIIII of FIG. 5, of the mechanisms including the cams;

FIG. 4 illustrates part of the mechanisms of FIG. 3, upon deactivation of the feeding automatic control means;

substantially along line v-v-v v of FIG. 3;

FIG. 6 is a top plan view of cam selectively engaging mechanism and first cam follower;

FIG. 7 is a fragmentary greatly enlarged side view of the cam track selectively engageable with either first and second cam followers;

FIG. 7A is an enlarged plan view of the stitching produced by engaging the first cam follower only with the cam of FIG. 7;

FIGS. 7B and 7C illustrate two ornamental and utility stitching patterns obtained by simultaneously engaging (in different phase relationship) both first and second cam followers with same cam of FIG. 7;

FIG. 7D diagrammatically illustrates the utility stitching produced by engaging the second cam follower only with same cam of FIG. 7; and

FIGS. 8A and 8B diagrammatically illustrate a plurality of ornamental and utility stitching patterns obtained by differently activating and deactivating the cam controlled and driven mechanisms.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In general, as shown in FIG. 1, the machine comprises a needle-bar 10 supported for lengthwise reciprocation (pro- 'vided by conventional means, not shown) in an oscillatable support 11, pivoted at 12 to the machine structure, the lateral oscillation being imparted by a conventional pitman 13, in directions AB. The work fabric feeding is provided by conventional up-and-down and back-and-forth motion of a feeddog 14, driven by a mechanism comprising a conventional link 15 and a rotatively reciprocatable shaft 16.

As known by those skilled in the art, the actual prevalent forward progressing in direction C of the work fabric, or the temporary backward motion thereof, in direction D, and the pace at which such motions occur, are provided by adjusting the phase relationship between up-and-down and back-andforth motions of feed-dog 14 and respectively the amplitude of rotary reciprocation of shaft 16.

The machine comprises a group of coaxial cams, and first cam follower 21 supported either for reciprocation in direction AB" and for shifting in direction E-F, parallel to the cam axis. Such first follower is linked (for example as hereinbelow described) to the pitman 13 for driving such pitman in direction A'-B and therefore oscillating the needlebar, at an amplitude determined solely by the cam track According to the fact that generally the production of zigzag stitchings of two different widths is desirable for utility purposes, preferably at least two cams of such profile for selectively providing such desired stitchings are comprised in the group 20.

An operator-controlled knob 30 (FIG. 2) is provided for selectively shifting the first cam follower 21 in direction E-F, by displacing such knob in direction EF'. The mechanism is designed so that at one end position of displacement EF of knob 30, the first cam follower 21 will be shifted outside the span covering the cam group 20, to deactivate the needle-bar oscillating mechanism.

A second cam follower 22 is provided for engaging, at operators command, one given cam in said group 20. Such given cam will be discussed below and it is indicated at 20A in FIGS. 3 to 5 and 7. The motion C"D of said second cam follower 22, when engaged with said given cam, controls the said phase relationship and amplitude of motions of feed-dog 14.

Upon deactivation of second cam follower 22, the said phase relationship (to provide backward motion of work fabric) is under operator control, as conventional, by acting on a control lever 34 in direction IL, and the said amplitude is also conventionally adjustable by acting upon a knob 33, in direction G, the motion in said direction G leading to an increasing of pace, or length of stitches. Preferably, the same knob 33 is made use of for operators activation and deactivation of the automatic feeding, that is the mechanism having said second cam follower as this prime mover. The activation of such mechanism is provided by further rotating the knob 33 in direction H, beyond the position of zero stitch length.

The machine is preferably but not necessarily provided with a third cam follower 23, and with a slide plate 24 which can be laterally reciprocated in direction OP upon reciprocation ()-P"of said third cam follower, provided by a particular cam preferably of such cam track profile to provide a path for the stitching including a plurality of arcs or curves, each including a number of stitches corresponding to a complete revolution of the cam group 20, that is to a complete recurring embroidery pattern as provided by any of the cams of group Activation and deactivation of said third cam follower 23 can be provided by action exerted in direction MN on a small knob 31.

The simplicity of operation by the operators part is evident from a consideration of FIG. 2. The machine, while fully automatized and capable of providing a wide variety of stitch patterns, includes an exceedingly small number of knobs. No incompatible or erroneous manuevering can be made by an even unskilled operator. Upon deactivation of all mechanisms, the machine provides the plain straight stitching at a pitch adjustable by acting in direction G on knob 33. By acting on knob 30, a selection between a plurality of zigzag or embroidery pattern can be made, having the best predetermined width and the pitch adjusted at will by acting on knob 33.

By rotating the same knob 33 in direction H, the feed of work fabric is placed under automatic control to provide new and useful stitchings, as discussed below. By further acting on the knob 31, any of the straight, embroidery and utility stitching can be combined with the effect resulting from lateral reciprocation of the work fabric.

The preferred construction on the various mechanisms related to the invention will be evident from a consideration of FIGS. 3 to 6, wherein the other conventionally constructed means, such as the drive means, the stitch forming means and so on, have been omitted as not forming part of this invention.

The group 20 of cams is supported and driven by a shaft 40 (FIGS. 3 and 5) connected by worm gears 41 and 42 to the machine main shaft 43. The first cam follower 21 is secured to or integrally made with a sleeve 44 (FIG. 6) slidably supported in direction E-F in an oscillating structure 45, oscillatable, together with the cam follower 21, about shaft 46 (FIG. 3). The structure comprises a triangular lever 47 to which a pitman portion 48 is pivotally connected. Such pitman portion 48 is adjustably connected, by conventional means, to pitman 13 of FIG. I. As far as the scope and the objects of the invention are concerned with, the lever 47, which is oscillated by the first cam follower 21, can be assumed to be rigidly connected to the oscillatable support 11 of the needle-bar 10 (FIG. I) by a pitman member comprising the portions 13 and 48 The knob 30 (FIGS. 5 and 6) is secured to a lever 49 pivoted at 50 and which can be selectively secured in any position of a plurality of positions defined by a rack 51 (see FIG. 3), each one of which corresponds to engagement of the first cam follower 21 with a given one cam of group 20. An arm 52 (FIG. 6) provides the shifting E--F of sleeve 44 and of cam follower 21 upon action exerted upon knob 30.

The second cam follower 22 is located coplanarly with one given cam 20A of group 20. It is formed by the end portion of a lever 53 journaled about the shaft 54 of the knob 33. Another lever 55 is also journaled about shaft 54 and has a pin 56 secured to its free end. Such pin abuts from above on one end of a two-armed lever 57 (FIG. 5) the other end of which is pivotally connected to a pitman 58 which is connected to a conventional device, generally indicated at 59, for phase and amplitude adjustment of the motion C'D of shaft 16, that is of work fabric feeding. The operation of the device, as shown in FIG. 5, is well known in the art and it will not be described.

Such device is also conventionally operator controlled by acting on the knob 33, when the automatic feeding control means are deactivated. The operator control is provided by a conventional device 69 engaging within a conventionally shaped groove (indicated at 68 in FIG. 3 in dot-and-dash lines) provided into a disclike component 66 secured to the shaft 54 and rotatively connected to knob 33. The said device 69 is also connected to pitman 58 by means of a second twoarmed lever 70. The manual adjustment of the stitching pitch is provided when the knob 33 is rotated as indicated at G in FIG. 2.

The outer or peripherical face of said disclike component 66 forms however a cam track having a protruding arc portion 66, which engages a pin 65 (FIG. 3), when the knob 33 is rotated in direction H of FIG. 2, supported at one end of a small two-armed lever 62 oscillatable about a pivot pin 61 secured to said another lever 55, causing the opposite end 63 of said small lever 62 to abuttingly engage a notch 64 of the lever 53, and thus maintaining the two coaxially swingable levers 53 and 55 at a given angular relative displacement, against the force exerted by a spring 60, connected between said levers and biasing such levers towards each other.

Therefore, when the said small lever is in the position shown in FIG. 3, the device is activated because the motion of the second cam follower 22, that is of lever 53, causes a corresponding motion of lever 55 and of link 58, thus a control of device 59. Such activation is provided by rotating in direction H said knob 33, that is by causing the part 66' of the camming periphery of component 66 to urge (by means of pin 65) the small lever 62 to said position.

If the knob 33 and hence the component 66 is rotated in direction G (FIG. 2), the part 66 of said camming periphery will no more engage the pin 65 and will disengage the end 63 from notch 64, so that the spring 66 will space the second cam follower 22 from the camming track of cam 20A, as shown in FIG. 4, therefore providing deactivation of the automatic feeding control.

The third cam follower 23 is formed at one end of another two-armed lever pivotally supported by a pivot pin at 28, and the other end 26 of which is pivotally connected to a link or pitman 27 which is conventionally connected to the slide plate 24, urged in direction by a spring 29. This latter mechanism is conventional in the art, and it can be deactivated at operator command by acting of the small knob which by means of a lever 32 (FIG. 5) conventionally spaces the third cam follower from the track of its particular cam 25.

As shown in FIG. 3, wherein said cam 25 is mostly shown by a phantom line, as being concealed by cams of group 20, the periphery of such cam is shaped according to a cardioid configuration, for cyclically imparting to the slide plate 24 a lateral reciprocation such to provide a stitching path formed by a number of curved portions.

The important to configuration of cam A will be now discussed with reference to FIGS. 7 and 7A-7D. In FIG. 7 the angular displacement of the cam, between any second stitch formation and step of progression of the feeding means, is indicated at P. The cam track comprises a sequence of protruding and recessed parts 80 and 81, the protruding parts 80 spanning each one circular pitch P", while the recessed parts span two circular pitches P.

Said cam 20A can simultaneously engage both first and second cam followers 21 and 22, as shown. As conventional, as first cam follower 21 is concerned, the engagement with parts 80 and 81 causes a stitch crossing the mean stitching line. As the second cam follower 22 is concerned, engagement on a recessed part leads to regular forward feeding of work fabric, while when a protruding part is engaged, the feeding mechanism will move one step rearwards the work fabric.

Assuming now that the first cam follower 21 only is active, that is engaging cam 20A, a stitching pattern such as shown in FIG. 7A is provided. Such pattern is a "modified zigzag, wherein between any two subsequent pair of zigzag stitches p' and p", a straight stitch p is provided, all said straight stitches p being aligned along a line at one side of the zigzag basic stitch pattern.

The cam 20A provides a sequence of feeding one back and two forth," when acting on second cam follower 22. When both cam followers'21 and 22 engage the cam, one of the stitches p, or p, or p will be made in backward motion of the work fabric, according to the relative angular position of cam followers with respect to the cam track profile. In the pattern of FIG. 7 B the stitches p are made in backward motion of the fabric, while in FIG. 7C the straight stitches p are backwardly made.

The novel stitching of FIG. 7C is of particular interest. It is a crossed zigzag of attractive design and of relevant utility for joining fabrics, sail cloths and so on. It is longitudinally expansible as a conventional zigzag stitching is.

By the activation of second cam follower 22, the above sequence provides that, in any longitudinal pitch P of the stitching, three stitches are present. Such feature provides a new and useful straight stitching such as shown in FIG. 70, when the second cam follower 22 alone is active. For clarity of illustration, in FIG. 7D the stitching apparently comprises two straight laterally spaced lines and diagonals therebetween. It must be imagined that actually all stitches present in any pitch P' are superimposed so that a triple" straight seam is made which is also expansible as a zigzag stitching is. In addition, it is a soft, relieved stringlike attractive stitching.

The effects resulting by activating and deactivating the second cam follower operated mechanism, while the first cam follower operated one is active, can be readily understood by a comparison of the stitching patterns of FIGS. 8A and respectively 88. For example:

the conventional zigzag pattern 82b will become a triple" zigzag such as at 82a, upon activation of second cam follower 22;

the stepped zigzag 83b (that is a stitching wherein the complete zigzag reciprocation comprises six 'stitches) will provide the very attractive embroidery stitching indicated at 83a, comprising a plurality of small adjacent diamonds;

among the others, the lowest pattern of FIG. 8B, which is a further modified zigzag of interest, provides the very attractive lowest stitching of FIG. 8A, which is similar to the so called Turkish stitch" in demand and which can be provided by special purely professional embroidery machines.

Any pattern either straight and zigzag or embroidery can be modified into a curves path by activating also the slide plate mechanism, if the machine is provided with. The patterns indicated at 83b and 83a are examples thereof.

Iclaim:

1. In a zigzag sewing machine, in combination, an embroidering device comprising a needle-bar having a needle; drive means for effecting up and down movements of said needie-bar so that said needle makes successive penetrations of a fabric; first rotary cam means and first cam follower means operatively connected with said needle-bar for oscillating the same in opposite transverse strokes between two extreme positions for making transverse opposite strokes in synchronism with said up and down movements so that said needle makes a fabric penetration at the beginning and at the end of opposite transverse strokes and produces transverse stitches; reversible feeding means for feeding the fabric under said needle; and second rotary cam means and second cam follower means operatively connected with said feeding means for effecting cyclical operation of said feeding means so that the fabric is moved in a plurality of steps forward, and then one step rearward during each cycle, said first and second cam means being synchronized so that a step of the fabric takes place between two opposite transverse strokes and between two successive fabric penetrations by said needle.

2. An embroidering device as claimed in claim 1 wherein said first cam means has an axis of rotation and includes cam track portions concentric with said axis and having such a circumferential extension that a straight line stitch is made between two fabric penetrations, and other rising and falling cam track portions by which said opposite transverse strokes are effected.

3. An embroidering device as claimed in claim 2 comprising adjusting means for circumferentially.adjusting at least one of said first and second cam follower means in circumferential direction of the respective cam means so that either a straight line stitch or a transverse zigzag stitch is made during the rearward step of the fabric.

4. An embroidering device as claimed in claim 1 wherein said feeding means is controlled by said second cam means to move the fabric two steps forward and one step rearward during each cycle.

5: An embroidering device as claimed in claim 1 wherein said first cam means include a stack of pattern cams; and wherein said first cam follower means cooperates with any selected one of said pattern cams.

6. An embroidering device as claimed in claim 1 wherein said second cam means includes a feed controlling cam located in said stack and adapted to be selected for engagement with said first cam follower means while being also engaged by said second cam follower means.

7. An embroidering device as claimed in claim 1 wherein said second cam means include a feed controlling cam having a cam ftrac'k with projecting and recessed portion, each recessed portions having twice the circumferential extension than each projecting portion so that said fabric moves two steps forward and one step rearward during each cycle.

8. An embroidering device as claimed in claim 1 wherein said feeding device includes adjusting means for adjusting the length of said stitches and including a manually operable knob; comprising means connecting said knob with said second cam follower means so that the same is spaced from said second cam means and inoperative in one position of said knob; and wherein said knob has other positions for operating said adjusting means and for placing said second cam follower means in engagement with said second cam means.

Claims (8)

1. In a zigzag sewing machine, in combination, an embroidering device comprising a needle-bar having a needle; drive means for effecting up and down movements of said needle-bar so that said needle makes successive penetrations of a fabric; first rotary cam means and first cam follower means operatively connected with said needle-bar for oscillating the same in opposite transverse strokes between two extreme positions for making transverse opposite strokes in synchronism with said up and down movements so that said needle makes a fabric penetration at the beginning and at the end of opposite transverse strokes and produces transverse stitches; reversible feeding means for feeding the fabric under said needle; and second rotary cam means and second cam follower means operatively connected with said feeding means for effecting cyclical operation of said feeding means so that the fabric is moved in a plurality of steps forward, and then one step rearward during each cycle, said first and second cam means being synchronized so that a step of the fabric takes place between two opposite transverse strokes and between two successive fabric penetrations by said needle.

2. An embroidering device as claimed in claim 1 wherein said first cam means has an axis of rotation and includes cam track portions concentric with said axis and having such a circumferential extension that a straight line stitch is made between two fabric penetrations, and other rising and falling cam track portions by which said opposite transverse strokes are effected.

3. An embroidering device as claimed in claim 2 comprising adjusting means for circumferentially adjusting at least one of said first and second cam follower means in circumferential direction of the respective cam means so that either a straight line stitch or a transverse zigzag stitch is made during the rearward step of the fabric.

4. An embroidering device as claimed in claim 1 wherein said feeding means is controlled by said second cam means to move the fabric two steps forward and one step rearward during each cycle.

5. An embroidering device as claimed in claim 1 wherein said first cam means include a stack of pattern cams; and wherein said first cam follower means cooperates with any selected one of said pattern cams.

6. An embroidering device as claimed in claim 1 wherein said second cam means includes a feed controlling cam located in said stack and adapted to be selected for engagement with said first cam follower means while being also engaged by said second cam follower means.

7. An embroidering device as claimed in claim 1 wherein said second cam means include a feed controlling cam having a cam track with projecting and recessed portion, each recessed portions having twice the circumferential extension than each projecting portion so that said fabric moves two steps forward and one step rearward during each cycle.

8. An embroidering device as claimed in claim 1 wherein said feeding device includes adjusting means for adjusting the length of said stitches and including a manually opErable knob; comprising means connecting said knob with said second cam follower means so that the same is spaced from said second cam means and inoperative in one position of said knob; and wherein said knob has other positions for operating said adjusting means and for placing said second cam follower means in engagement with said second cam means.

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