US3653475A

US3653475A - Friction clutch

Info

Publication number: US3653475A
Application number: US42013A
Authority: US
Inventors: W Vincent Thelander
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-06-01
Filing date: 1970-06-01
Publication date: 1972-04-04
Anticipated expiration: 1989-04-04

Abstract

The present small diameter low cost clutch units embody improvements over those of our U.S. Pat. Nos. 1,985,301 and 2,214,789 centered in the release levers, which, while still affording the mechanical advantages of the previously patented clutches of higher engaging pressure with lighter pedal pressure for disengagement, are pivotally connected at their outer ends to the drive lugs on the pressure plate and have novel low friction oscillatable stirrup type fulcrum members to fulcrum the levers near their outer ends on the spider or back plate. These stirrup members compensate by their oscillation for the slight change in center distance between the fulcrum and pivot pin during clutch operation for not only lower friction but reduced wear, while the pivot pin tieup of the levers with the drive lugs on the pressure plate results in the levers giving added engaging pressure due to centrifugal force, which advantage can easily be augmented by adding weight to the back of the levers at their outer ends. The stirrups may be of one piece I-shaped construction, as in one of the present clutches, or of an adjustable type, as in the other clutch.

Description

United States Patent Thelander [451 Apr. 4, 1972 [54] FRICTION CLUTCH W. Vincent Thelander, P.O. Box 385, Sugar Loaf Mountain Ranch, Cave Creek, Ariz. 85331 22 Filed: June 1,1970

21 Appl.No.: 42,013

[72] Inventor:

[52] US. Cl. ..192/99 A, 192/98, 192/7029, 285/8, 267/174 [51] Int. Cl. ..Fl6d 21/00 [58] Field of Search ..192/99 A, 70.26, 70.29, 70.3, 192/89 R, 98 A, 105 C; 285/83; 267/174, 177, 178

[56] References Cited UNITED STATES PATENTS 502,620 8/1893 Fisher ..85/8.3 2,021,973 11/1935 Wenp.... ....l92/99 Primary Examiner-Mark M. Newman Assistant Examiner-Randall Heald Attorney-Andrew F. Wintercorn [57] ABSTRACT The present small diameter low cost clutch units embody improvements over those of our US. Pat. Nos. 1,985,301 and 2,214,789 centered in the release levers, which, while still affording the mechanical advantages of the previously patented clutches of higher engaging pressure with lighter pedal pressure for disengagement, are pivotally connected at their outer ends to the drive lugs on the pressure plate and have novel low friction oscillatable stirrup type fulcrum members to fulcrum the levers near their outer ends on the spider or back plate. These stirrup members compensate by their oscillation for the slight change in center distance between the fulcrum and pivot pin during clutch operation for not only lower friction but reduced wear, while the pivot pin tieup of the levers with the drive lugs on the pressure plate results in the levers giving added engaging pressure due to centrifugal force, which advantage can easily be augmented by adding weight to the back of the levers at their outer ends. The stirrups may be of one piece l-shaped construction, as in one of the present clutches, or of an adjustable type, as in the other clutch.

11 Claims, 13 Drawing Figures Patented April 4, 1972 3 Sheets-Sheet 1 m N M M E 5 Wm M a w V W if g A T TOR/V5 Patented April 4, 1972 5 Sheets-Sheet 2 ATTORNEY Patented April 4, 1972 I5 Sheets-Sheet 5 398.5 LB.X3 n75 TOTAL TRAVEL I R a M a W D mwBGAG S NEN O R IL E 4TER T J I R A T A A PR 4.A =TN F 2R3SO 0 KW 4 5 W L R E T N E. C 2 B Y M a L4 4 SHAFT l6 FIG 10' m R W 4 w a W m w a N W W ATTORNEY FRICTION CLUTCH This invention relates to friction clutches for use on automobiles and other vehicles, the new mini cars, for example, having created the need for a smaller diameter, low cost, clutch unit, and the present invention being more particularly concerned with improvements in the type of clutch disclosed in Thelander et al. US. Pat. No. 1,985,301 and my U.S. Pat. No. 2,214,789, in which, by virtue of the use of novel springpressed release levers, the back plate can be reduced to an open spider form, exposing the pressure plate for cooler operation and longer clutch plate facing life.

In the clutches disclosed in the patents referred to, the levers operated by the throw-out collar to engage and disengage the clutch are pivotally mounted so that the engaging springs have a certain mechanical advantage to obtain multiplied engaging pressure, while there is nevertheless a mechanical advantage derived in the disengaging operation of said levers by the throw-out collar so that the clutch can be disengaged with lighter pedal pressure. A clutch of that general design presents special problems in its practical applications for which it is the principal object of my present invention to provide solutions by improvements in design and construction.

One object with the present design is to provide a clutch of the type mentioned having a low friction stirrup type fulcrum between the spider and each of the spring-pressed release levers near the outer end thereof, which is pivotally connected to the pressure plate, the novel stirrup serving also by its freedom to oscillate to compensate for any slight change in center distance between its V-shaped fulcrum and the pivot pin in the pressure plate during clutch operation, the ability to compensate for the variation in center distance between the two pivots resulting in a further considerable reduction in friction and wear that would otherwise have to be tolerated, while the pivot pin tieup of the levers and spring system with the sturdy pressure plate assures sufi'icient strength to withstand the highest centrifugal effect, while the present design loses none of the important advantages of the aforementioned patented constructions, namely:

1. Exposure of the pressure plate for good heat dissipation, a cooler pressure plate giving longer facing life on the clutch plate;

2. The multiplied lever ratio inherent in the patented designs necessitating only three springs instead of the usual six or nine, and the fact that the springs are located between the levers and the spider and are therefore out of contact with the pressure plate, which is the heat dissipating member, so that the springs are not subjected to high temperatures and there is no spring pressure loss due to loss of temper;

3. The spider, being of stamped sheet metal construction and largely of channel section, provides rigid support for the lever fulcrums so that there is very little deflection and consequently very little loss of pedal travel due to deflection, and

4. It is still possible to insert shipping spacers between the outer ends of the levers and the spider, which are removed after the clutch has been mounted on the flywheel.

Another object with the present design is to impart a small amount of additional engaging pressure to the pressure plate due to .the centrifugal effect of locating the levers center of gravity above the fulcrum, the amount of this effect being variable easily by slight design changes, as for example, forming a lip on the release lever in proximity to the pivot pin and welding a weight thereto at a predetermined radius with respect to the pivot axis.

Another object is to provide for ease of assembly of the stirrups by insertion through slots in the lever and spider, and also having the pivot pins, which are easily assembled on the levers through holes in the drive lugs on the pressure plate, each provided with a groove in the middle portion through which a compressible resilient roll pin can be easily inserted in the lugs to lock the pivot pins in place without riveting or using cotter pins or lock rings.

Another object is to provide a clutch of the novel design described above in which either of two means can be used for easily setting all of the release levers at uniform engaging height:

1. An adjusting screw can be provided at the inner end of each lever having a rounded surface on the adjusting head end arranged to make point contact with the throwout bearing, or

2. Special stirrup bolts of T-design can be used, each having one pair of fulcrums on the crossbar of the T to rock on the spider and another pair of fulcrums provided on a collar slidable on the threaded shank and arranged to rock on the lever while being adjustable longitudinally relative to the bolt by means of an adjusting nut threaded on the rear end of the shank.

The invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a rear view of a clutch embodying my invention;

FIG. 2 is a cross-section on the line 2-2 of FIG. 1, indicating in dotted lines a portion of the flywheel and driven shaft along with the throwout bearing, that is, of course, operable in the usual way by means of the clutch pedal (not shown);

FIGS. 3 and 4 are views corresponding to portions of FIGS. 1 and v 2 but showing an adjustable stirrup for each release lever in lieu of the adjusting screws at the inner ends of the levers;

FIGS. 5 and 6 are two views at right angles to one another of one of the stirrups used in the clutch of FIGS. 1 and 2, showing this part on a larger scale;

FIG. 7 and 8 are two views at right angles to one another of one of the lever pivot pins, shown on a larger scale;

FIG. 9 and 10 are views at right angles to one another of one of the compressible resilient roll pins used for locking the pivot pins in place without riveting or using cotter pins or lock rings, while still facilitating assembly and reducing cost;

FIG. 11 and 12 are views at right angles to one another of one of the release levers, FIG. 11 being a section on the line 11-11 of FIG. 12 and including a showing in dotted lines of an additional feature of a rearwardly projecting lug on the back of the pivoted end of the lever having a small weight welded thereto to add a desired amount of additional pressure on the pressure plate due to centrifugal effect, this effect being variable, of course, by merely varying the amount of weight added, and

FIG. 13 is a geometrical diagram to enable a better understanding of the present stirrup fulcrum friction clutch construction, the centrifugal effect that accounts for additional pressure on the pressure plate by virtue of this novel construction being omitted from consideration in this diagram.

Similar reference numerals are applied to corresponding parts throughout the views.

Referring first to FIGS. 1, 2, and 5 to 12, the reference numeral 14 designates a flywheel mounted on the rear end of a crank shaft 15 and forming the driving element. A shaft 16 constituting the driven element extends rearwardly from the clutch into the gear box of the transmission in the usual way. At 17 is indicated the clutch throwout bearing movable in the usual way by means of the clutch pedal (not shown). The clutch comprises a disk 18 carried on a hub 19 splined on the front end of the shaft 16, and a pressure plate 20 disposed behind and in concentric relation with the matted portion of the disk 18 to cause engagement thereof with the flat face 22 on the flywheel. In accordance with the disclosure in Thelander et al. US. Pat. No. 1,985,301, a plurality of release levers 23 are provided which are arranged to be depressed against the action of compression springs 24 by clutch pedal operation of the throwout bearing 17 against the inner ends 25 of the levers to disengage the clutch. In the Thelander et al. US. Pat. No. 1,985,301, as well as in my US. Pat. No. 2,241,780, these levers 23 were pivoted on the spider 26 near the outer end to transmit pressure of the springs 24 in a multiplied degree to the pressure plate 20, and, while the pressure of the springs 24 is multiplied through the levers 23 for clutch engagement, it is nevertheless clear that there is an appreciable mechanical advantage also in the disengagement of the clutch by reason of the fact that the springs 24 are closer to the pivots than the inner ends 25 of the levers 23 where the throwout bearing 17 engages, and this mechanical advantage accordingly makes for lighter pedal action. There is still another advantage in this location of the springs 24 with respect to the pivots from the standpoint that there is very little loss of spring pressure when the clutch facings or mats 21 become worn, because there is so little expansion of the springs permitted in proportion to a given amount of wear of the facings.

In accordance with the present invention, however, I have pivotally connected the outer ends of the release levers 23 by pivot pins 27 to the drive lugs 28 that extend rearwardly from the pressure plate 20. These have flat side faces parallel to one another and to radii of the pressure plate slidably engaging the opposite sides of slots 29 provided in the vertical back wall 30 of the spider 26 so as to transmit drive through the spider 26 and pressure plate 20 to the clutch disk 18. Furthermore, in accordance with the present invention, each of the release levers 23 is fulcrumed near its outer end on an I-shaped stirrup member 31, the

cross-portions

32 and 33 at opposite ends of which provide pairs of

fulcrum surfaces

34 and 35 coined on the inner edges, as best appears in FIGS. and 6, for line contact antifriciton fulcruming of the cross-portion 32 on opposite sides of the slot 36 in the rearwardly embossed portion 37 of the spider 26, and similar fulcrum engagement of the other cross-portion 33 on opposite sides of the slot 38 of the forwardly embossed portion 39 of the web of the generally channel-shaped release lever 23 next to the pivoted outer end thereof. The

slots

36 and 38 are long enough and wide enough in relation to the

cross-portions

32 and 33 of the stirrup member 31 to permit insertion through these slots in assembling the stirrup members 31 on the spider and levers after the spring-24 for each lever has been assembled in place resting on the circular seat 40 defined for one end of the spring on the spider 26 while the other end has line bearing contact at diametrically opposite sides of the other end on a crossbar 41 defined in the semi-open end of the frusto-conical pocket 42 provided on the release lever 23 intermediate the ends thereof, a lug 43 being struck inwardly from the end of the pocket 42 on one side thereof to engage in the end of the spring 24 and assure its remaining always in centered relationship to the crossbar 41.

The pivot pin 27, for each release lever 23, is received in a hole 44 in the drive lug 28 and registering holes 45 in longitudinally extending flanges 46 provided on the release lever, and has an annular groove 47 provided at the middle thereof, as best shown in FIG. 7, which comes into register with a small hole 48 provided in the lug 28 that intersects the hole 44 at one side thereof, as seen in FIG. 2, so that when a hollow cylindrical resilient roll pin 49, shown in FIGS. 9 and 10, is compressed and pressed into place in the hole 48 it permanently secures the pivot pin 27 in place, since the slight amount of compression of the roll pin necessary for entry in the hole 48 eliminates any likelihood of this retaining pin ever coming out, and thus the construction is really reduced to its lowest terms so far as simplicity and economy is concerned, as there is no need for any riveting nor any use of a cotter pin or a lock ring. The cutout at 49' of the web of the channel at the outer end of the lever 23 enables easy access to the hole 48 in entering pin 49.

The corner portions 50 provided at the outer ends of the flanges 46 on the release levers serve as positive stops to limit forward or engaging movement of the pressure plate 20 under spring action of the levers 23 and under centrifugal force of the levers in high speed operation of the engine, but, of course, the facings 21 on the clutch plate 18 normally prevent these positive stops 50 from coming into contact with the spider 26. These comer portions 50, however, do cooperate with shipping shims, like that indicated in dotted lines at 51 in FIG. 2, inserted between each lever 23 and the spider 26 in the shipment of a clutch unit, these spacers being removed after a clutch has been mounted on the flywheel.

The spider 26, as seen in FIG. 1, is of open generally triangular form and of flanged sheet metal construction providing three mounting feet 52 adjacent the three release lever mountings, where bolts are entered at 53 to fasten the clutch unit to the back of the flywheel. After removal of the shims 51 there remains only the adjustment of the three screws 54 adjustably threaded in the extruded threaded portions 55 provided on the inner ends of the release levers. These screws, when properly adjusted, have the rounded back faces on the heads of the screws disposed in a common plane parallel to the spider 26 and pressure plate 20, and, of course, in a predetermined spaced relationship to the throwout bearing 17 in the engaged position of the clutch so that it requires only a predetermined pedal movement forwardly to disengage the clutch.

In operation, looking at the construction of FIGS. 1 and 2, and the operation diagram of FIG. 13, it is seen that I have retained the mechanical advantage of the aforementioned two patents in obtaining multiplied engaging pressure, and at the same time retained the mechanical advantage derived in the disengaging operation of the levers 23 by the throwout bearing 17 so that the clutch can be disengaged with light pedal pressure, and so that with a starting pressure of only 260 lbs. on the release bearing 17 (with much less pedal pressure) there is, in contrast to that, a pressure of 1,175 lbs. on the pressure plate holding the clutch engaged, not counting centrifugal effeet. The latter, by virtue of the present novel design, is of appreciable value because the levers 23 actually impart an appreciable amount of additional pressure to the pressure plate due to the centrifugal effect obtained by having the center of gravity of each lever above the fulcrum 31, and, as seen in FIG. 1 1, the amount of this centrifugal effect can be varied by slight design changes, a substantial effect being achieved, for example, by providing a lug 54 extending rearwardly from the pivoted end of the release lever and welding a metal weight 55 thereto by a tack weld on the line 56. The antifriction stirrup fulcrum pivots 31 for the levers 23 reduce pedal pressure in disengagement of the clutch while making the full pressure of springs 24 available for the multiplied clutch engagement spring pressure. The stirrups 31 also compensate for any slight changes in center distance between their V-shaped fulcrums 36 and the pivot pins 27 during clutch operation, and it goes without saying that this ability to compensate for variation in center distance accounts in itself for an even greater reduction in friction and wear normal in a two pin design. The present design also permits retaining the other important advantages of:

I. the exposed pressure plate 20 for good heat dissipation and resultant longer facing life for disk 18, and

2. locating the springs 24 between the levers 23 and the spider 26 to protect the springs from extremely high temperatures so that the springs suffer no loss of pressure due to loss of temper.

In closing, attention is called to FIGS. 3 and 4 in which the adjustable stirrup 31 is employed with a view to retaining most of the advantages described for the construction of FIGS. 1 and 2 while permitting the adjustment of the clutch to be taken care of at the stirrups 31 instead of at the inner ends of the levers 23' with adjusting screws 54, the levers 23' having their inner ends 56 merely rounded for line contact directly with the throwout bearing 17. Levers 23 are pivoted similarly as in the other construction by means of pivot pins 27' to the drive lugs 28' on the pressure plate 20, although in this case a lock ring 57 is shown as entered in an annular groove in one end of the pivot pin to retain it, the other end having a head as shown at 58. The lugs 28, of course, have sliding drive transmitting engagement on opposite sides of the slots 29 in the spider 26', similarly as in the other construction, but the principal difference here is the adjustable stirrups 31, each of which is in the form of a T-bolt 59, the crosshead 32 on one end of which provides diametrically opposed fulcrums 34' for line contact low-friction rocking engagement with the spider 26 in the embossed portion 37' on opposite sides of the slot 36', while a separate collar 60 having diametrically opposed V-shaped fulcrums 35' engaging in the indented portion 39' near the pivoted end of the lever 23' on opposite sides of the slot 38' is adjustably mounted on the shank of the T-bolt 59 in front of the nut 61 that is threadedly adjustable on the threaded outer end of the shank. This permits making the adjustment of the clutch at the stirrups 31', while checking gauges for lever height are in contact with the levers 23'.

A slightly different lever construction is best shown in FIG. 4 using a separate spring cup 62 that has a forked extension 63 that extends through a hole 64 in the lever 23' and has laterally projecting V-shaped fulcrums 65 on the two arms thereof that have line contact low-friction rocking engagement in the V-shaped cutouts 66 provided in the edge portions of the longitudinally extending flanges 67 of the lever 23. There is also low-friction line contact diametrically of the outer end of the spring 24 on the transverse fulcrum 41' provided on the inner side of the cap 62. The inner end of the spring 24 is seated in a circular depression 40' provided in the spider 26' similarly as in the other construction. Of course, there is no reason why the cup 62 cannot be made integral with the lever 23 similarly as the portion 42 of the lever 23 in the other construction, if that is preferred.

The operation of this adjustable fulcrum clutch construction is substantially the same as the other clutch construction first described.

it is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. While a preferred embodiment of the invention has been illustrated and described, this is only for the purpose of illustration, and it is to be understood that various modifications in structure will occur to a person skilled in this art.

I claim:

1. In a clutch comprising a driving element and a driven element, a pressure plate for holding the driving and driven elements frictionally engaged, a lever support, a lever substantially radially disposed with respect to and behind both the lever support and pressure plate pivotally connected at its outer end to a projection on the pressure plate that extends rearwardly therefrom through an opening provided therefor in the lever support to provide a driving connection between the pressure plate and lever support, spring means caged between the lever and lever support intermediate the ends of the lever and spaced radially inwardly with respect to said pressure plate projection to apply increased clutch engaging pressure to the pressure plate in a predetermined ratio to disengaging pressure, the lever support and lever having registering slots provided therein between the spring means and said projection, and a generally ,l-shaped stirrup member inserted through said registering slots and having parallel cross-portions on the opposite ends thereof, one of which has low friction line contact fulcrum engagement on the lever support on opposite sides of the slot therein, the other portion having low friction line contact fulcrum engagement on the lever on opposite sides of the slot therein, said stirrup member being oscillatable through a small angularity relative to the first mentioned cross-portion to compensate for slight change in center distance between the lever pivot and the fulcrum provided by the last mentioned cross-portion of said stirrup member.

2. A clutch as set forth in claim 1, wherein the cross-portions of the fulcrum stirrup member, which are substantially parallel to one another and in co-planar relationship have the inner edges coined to compress the metal to closer grain and define longer wearing fulcrum surfaces, one pair of these surfaces being on a common radius of small diameter in relation to the curvature of the lever support surfaces which this pair is to engage, and the other pair of these surfaces being generally V-shaped for rocking engagement with the surface on the release lever to be engaged thereby.

3. In a clutch comprising a driving element and a driven element, a pressure plate for holding the driving and driven elements frictionally engaged, a lever support, a lever substantially radially disposed with respect to and behind both the lever support and pressure plate pivotally connected at its outer end to a projection on the pressure plate that extends rearwardly therefrom through an opening provided therefor in the lever support to provide a driving connection between the pressure plate and lever support, spring means caged between the lever and lever support intermediate the ends of the lever and spaced radially inwardly with respect to said pressure plate projection to apply clutch engaging pressure to the pressure plate in a predetermined ratio to disengaging pressure, means between the pivot and the spring means whereby said lever is fulcrummed relative to said lever support for application of the pressure of said spring means to said pressure plate in a multiplied degree, the radially inner end of said lever being manually operable to release the clutch.

4. A clutch as set forth in claim 3, wherein the pivot pin connecting the outer end of the lever to the pressure plate projection has an annular groove provided therein at the middle thereof, the projection having a hole provided therein in transverse relationship to said pin and intersecting the annular groove provided therein, and a pin for locking the pivot pin in place entered in said hole, the retaining pin being of rolled resilient sheet metal construction so as to be hollow and split lengthwise of one side and being normally of slightly larger diameter than the hole in the projection that is to receive it, whereby, when compressed and entered in the hole, said pin is held resiliently against removal from said hole.

5. In a clutch comprising a driving element and a driven element, a pressure plate for holding the driving and driven elements frictionally engaged, a lever support, a lever substantially radially disposed with respect to and behind both the lever support and pressure plate pivotally connected at its outer end to a projection on the pressure plate that extends rearwardly therefrom through an opening provided therefor in the lever support to provide a driving connection between the pressure plate and lever support, spring means caged between the lever and lever support intermediate the ends of the lever and spaced radially inwardly with respect to said pressure plate projection to apply increased clutch engaging pressure to the pressure plate in a predetermined ratio to disengaging pressure, the lever support and lever having registering slots provided therein between the spring means and said projection, a T-bolt insertable through the slots so that the cross-portion of the T is disposed transversely relative to the slot in the lever support and rests against the lever support on opposite sides of said slot to serve as a fulcrum for rocking engagement of the T-bolt on said lever support, a collar adjustably received on the other end of said bolt, which is threaded, said collar having diametrically opposed fulcrum projections engaging the lever on opposite sides of the slot therein to serve as a fulcrum therefor, and an adjusting nut threaded 0n the end of said bolt against said collar.

6. A clutch as set forth in claim 5, wherein the fulcrum surfaces on the cross-portion of the T-bolt are rounded on a smaller radius than the radius of the surface on the lever support with which the same are adapted to engage, the fulcrum surfaces on the collar being generally V-shaped.

7. A clutch as set forth in claim 19, wherein all of the fulcrum surfaces are coined to compress the metal to closer grain and thus define longer wearing surfaces.

8. In a clutch comprising a driving element and a driven element, a pressure plate for holding the driving and driven elements frictionally engaged, a lever support, a release lever substantially radially disposed with respect to the lever support and pressure plate pivotally connected at its outer end to a projection on the pressure plate that extends rearwardly therefrom through an opening provided therefor in the lever support to provide a driving connection between the pressure plate and lever support, spring means caged between the lever and lever support intermediate the ends of the lever and spaced radially inwardly with respect to said pressure plate projection to apply clutch engaging pressure to the pressure plate, the spring means comprising a coiled compression spring, one end of which bears against the lever support and the other end of which bears against the lever intermediate the ends thereof, the lever having a separate cup element in which the other end of said coiled compression spring is seated, the cup element having a forked extension extending through an opening provided in the lever intermediate the ends thereof, means fulcruming the two legs of the fork relative to the lever on opposite sides of the opening therein, means between the pivot and the spring means whereby said lever is fulcrumed relative to said lever support for application of the pressure of said spring means to said pressure plate in a multiplied degree, the radially inner end of said lever being manually operable to release the clutch.

9. A clutch as set forth in claim 8, wherein the separate cup has a fulcrum projection on the inner side thereof diametrically with respect to the adjacent end of the spring and substantially parallel to the lever pivot and bearing against the adjacent end of the spring.

10. A clutch as set forth in claim 8, wherein the separate cup element is an article of manufacture for engagement with the outer end of the coiled compression spring that exerts spring pressure against the clutch release lever, said cup element comprising a one piece sheet metal generally cylindrical cup having an inwardly flanged rim portion extending toward the release lever, on diametrically opposite sides of which are extensions in substantially parallel relation for extension through an opening provided in the release lever, the ends of said extensions having diametrically opposed V-shaped outward projections thereon for rocking fulcrum engagement with the release lever on the opposite sides thereof.

11. A clutch as set forth in claim 8, wherein the separate cup element is an article of manufacture for engagement with the outer end of the coiled compression spring that exerts spring pressure against the clutch release lever, said cup element comprising a one piece sheet metal generally cylindrical cup having an inwardly flanged rim portion extending toward the release lever, on diametrically opposite sides of which are extensions in substantially parallel relation for extension through an opening provided in the release lever, the ends of said extensions having diametrically opposed V-shaped outward projections thereon for rocking fulcrum engagement with the release lever on the opposite sides thereof, the cup having an inwardly embossed transverse abutment extending diametrically thereof in parallel relationship to said V-shaped projections adapted to have engagement diametrically with the outer end of said spring to space the same from the rest of the seat member for the purpose described.

inqnan

Claims

1. In a clutch comprising a driving element and a driven element, a pressure plate for holding the driving and driven elements frictionally engaged, a lever support, a lever substantially radially disposed with respect to and behind both the lever support and pressure plate pivotally connected at its outer end to a projection on the pressure plate that extends rearwardly therefrom through an opening provided therefor in the lever support to provide a driving connection between the pressure plate and lever support, spring means caged between the lever and lever support intermediate the ends of the lever and spaced radially inwardly with respect to said pressure plate projection to apply increased clutch engaging pressure to the pressure plate in a predetermined ratio to disengaging pressure, the lever support and lever having registering slots provided therein between the spring means and said projection, and a generally I-shaped stirrup member inserted through said registering slots and having parallel cross-portions on the opposite ends thereof, one of which has low friction line contact fulcrum engagement on the lever support on opposite sides of the slot therein, the other portion having low friction line contact fulcrum engagement on the lever on opposite sides of the slot therein, said stirrup member being oscillatable through a small angularity relative to the first mentioned cross-portion to compensate for slight change in center distance between the lever pivot and the fulcrum provided by the last mentioned crossportion of said stirrup member.

5. In a clutch comprising a driving element and a driven element, a pressure plate for holding the driving and driven elements frictionally engaged, a lever support, a lever substantially radially disposed with respect to and behind both the lever support and pressure plate pivotally connected at its outer end to a projection on the pressure plate that extends rearwardly therefrom through an opening provided therefor in the lever support to provide a driving connection between the pressure plate and lever support, spring means caged between the lever and lever support intermediate the ends of the lever and spaced radially inwardly with respect to said pressure plate projection to apply increased clutch engaging pressure to the pressure plate in a predetermined ratio to disengaging pressure, the lever support and lever having registering slots provided therein between the spring means and said projection, a T-bolt insertable through the slots so that the cross-portion of the T is disposed transversely relative to the slot in the lever support and rests against the lever support on opposite sides of said slot to serve as a fulcrum for rocking engagement of the T-bolt on said lever support, a collar adjustably received on the other end of said bolt, which is threaded, said collar having diametrically opposed fulcrum projections engaging the lever on opposite sides of the slot therein to serve as a fulcrum therefor, and an adjusting nut threaded on the end of said bolt against said collar.