GB2120332A - Friction coupling device, friction plate - Google Patents

Abstract

A friction coupling device specifically a brake comprises at least one friction plate (two plates 111, 112 as seen in Figure 5) slidably secured to a rotatable shaft 38 between a stop member 117 and an axially movable member 51. The friction plate(s) 111, 112 have planar side faces, and support friction elements in the form of buttons 113, 114 which pass through the friction plates, extend beyond the planar side faces and are mounted within the friction plates 111, 112 in a snug but floating manner to provide a pair of friction surfaces at opposite ends of the friction elements. The friction surfaces simultaneously engage respective members, e.g. the stop member and the axially movable member, upon the application of an axial force to the axially movable member. As seen in Figure 2, the plates are utilized in a disc brake 39 in a rotary actuator 11 with input member 12, output member 13 and planetary gear section 31, the member 51 being acted upon during overload to apply the brake A no-back ratchet arrangement is also disclosed (see e.g. Figure 4). The buttons may be of carbon, bronze etc. The friction plate may be rectangular (see Figure 9) other than a disc. <IMAGE>

Description

SPECIFICATION Friction device The invention relates to friction coupling devices.

Rotary friction brake and clutch arrangements have shown steady technological improvement over the past century as new materials and manufacturing techniques have provided new friction materials and material bonding procedures. The creation of new friction materials with long life and desirable frictional properties has motivated the industry to find new ways to bond or secure the materials to friction plates that are typically included in rotary friction brake and clutch arrangements. Early in the history of the friction brake and clutch art the use of solid carbon friction elements was recognized as highly desirable. In fact, shortly after the turn of the century the need for a self lubricating clutch arrangement called upon the employment of graphite blocks of carbon secured within clutch face members to co-act with the metallic face of a drive or driven member.

Dion et al.'s US Patent No. 804,104 is representative of this early recognition of the utility of a form of carbon as a friction element.

The Dion et al. patent created a single overall friction surface by inserting carbon blocks in the face of a disk. It was later found that twice the frictional surface could be made available by mounting carbon buttons in a floating manner in a reaction element of a friction device.

The use of button shaped friction elements continued to find usefulness in the design of friction members. Stanley's US Patent No.

1,655,827 some twenty plus years later employed button shaped inserts in a brake member in which the buttons were made of fibrous asbestos coupled with a binder. The asbestos fibre and binder inserts 11, Figures 3 and 4 were placed in openings 1 2 in a disc 1 0. The inserts 11 were cut to a length so as to project laterally the desired distance from the faces of the disc 10 and then were subject to a longitudinal pressure on their opposite ends which upsets them into the counter sinks as shown in Figure 4 thereby securely to hold the inserts on the disc 10.

The desirability of doubling the friction surface available for each button or insert was also recognized in the clutch by Whistler et aI.'s US Patent No. 2,054,872, which it can be seen in Figure 1 a that there are provided cork friction inserts 26 in openings 25 of a disc 20. The cork inserts which have been soaked in water are compressed to allow passage through the opening 25 in the disc 20 whereafter the cork inserts expand to rigidly secure themselves to the disc 20 as shown in Figure 1 a. Although Whistler et al.

has taken cognizance of the desirability of multiple friction surfaces provided for by the cork inserts 26, there is no apparent appreciation of the dynamic advantages of employing a friction insert mounted in a snug but yieldably lovable manner in a disc as will be explained at length in the invention to be described more fully hereinafter.

Some years later Cooley in US Patent No.

2,421,925 also recognized the desirability of multiple friction surfaces. Cooley in Figure 3 of his patent calls for friction inserts 27 made of porous metal which inserts 27 are snugly fit into a disc 1 6 and then peened into a fixed relationship with a supporting disc 1 6. Again we see no suggestion of a snug but yieldably movable friction insert of the type described in respect of the subject invention.

US Patent No. 2924314 to Shepard, Jr., is of interest because Shepard provides in the intermittent drive described in his patent an electromagnetic clutch 12 and a brake 1 4 which appear at first blush to present a technique of a floating friction element 55 in a reaction disc 40 which appears to be structurally similar to the snugly but yieldably movable friction insert of the instant invention to be described. Close examination of Shepard reveals, however, that Shepard's floating friction insert 55 is made of magnetic material which is attracted to clutch electromagnetic coil 24 or brake magnetic coil 56 to provide but a single friction surface for either the clutch or brake mode of operation of the intermittent drive.Absent from Shepard is a suggestion of a floating friction insert in a reaction plate that simultaneously cooperates with a pair of friction surfaces one of which at least is brought into engagement with a movable friction insert carried by the reaction plate.

Currently popular is the idea of bonding buttons made of metallic compositions to a metal disc.

Typical of this approach is that shown in Allen et al's US Patent No. 3,937,303 in Figures 1 and 2.

The cost of bonding the buttons 1 5 to a disc 11 and the attendant mechanical problems that arise when a bonded button or buttons break free during usage mitigates away from this approach when factors such as low cost and durability are of primary concern. The invention the subject of the present Application satisfies these just noted desirable factors in an admirable fashion.

Of final interest in a review of the prior art is Kuzarov's US Patent No. 3,986,588 which is directed to a brake-clutch assembly for a winch.

Kuzarov recognizes the value of positioning friction buttons 96 in a ratchet plate 54 (Figure 2), so that they can rotate freely and are mounted in a sufficiently loose interfit with a related hole so that moderate axial shifting is possible to compensate for surface irregularities or misalignment of components. Kuzarov, however, requires of his friction buttons that each have a head portion 100 that prevents the buttons 96 from moving through the plate 54 to provide multiple friction surfaces for each of the buttons as is the case with the invention the subject of this Application.

This invention provided a friction coupling device that includes a friction plate slidably secured to a rotatable shaft between a reaction member and an axially movable member, the friction plate having planar side faces and friction means mounted within the friction plate in a snug but yieldably movable manner to provide a pair of friction surfaces at opposite ends thereof, whereby the friction surfaces simultaneously engage the reaction member and the axially movable member to cause the frictional coupling of rotary movement of the rotatable shaft to the reaction member upon the application of an axial force to the axially movable member. Advantageously the friction plate has planar side surfaces.

In a preferred embodiment the friction coupling device is a brake and the reaction member is held stationary against rotary movement.

It is a particular advantage of the invention that the friction means employed is free from the need to be bonded to the friction plate. Thus the friction coupling device of the invention is low in cost, is readily manufactured and is easily assembled.

In the friction coupling device of the invention the friction means of the friction plate comprises at least a first friction element which passes through the friction plate and extends beyond both sides of the friction plate. The first friction element is mounted within the friction plate in a floating manner to thereby provide a pair of friction surfaces at opposite ends of the first friction element. The floating first friction element friction surfaces are situated adjacent parallel planar surface of the reaction member and the axially movable member such that the relative axial movement of the components causes the friction surfaces of the opposite ends of the floating friction element simultaneously to engage the axially movable member and to be frictionally coupled to the reaction member.

In a preferred embodiment of the invention there is slidably secured to the shaft an array of two or more similar friction plates alternating with similar axially movable members, so that the axial force from each axially movable member is transmitted to a next adjacent axially movable member through the intervening friction plate, whereby the friction surfaces of all but an endmost friction means simultaneously engage the axially movable members on opposite sides thereof to assist the frictional coupling of rotary movement of the rotatable shaft to the reaction member on the application of the axial force to the endmost axially movable member, friction elements are advantageously carbon and of uniform circular cross-section.

Drawings Figure 1 is a three dimensional illustration in partial section of a rotary actuator in which the improved friction device embodying the invention finds utility, Figure 2 is a schematic drawing of the rotary actuator of Figure 1, Figure 3 is a partial cross-section of the rotary actuator of Figure 1, Figure 4 is an exploded view, in three dimensional form, of a differential planetary reduction gear in combination with a no-back ratchet arrangement that operates in conjunction with the improved friction device of the invention, Figure 5 is a partial section of a disc brake embodying the invention, Figure 6 is a front view of a friction plate embodying the invention, Figure 7 is a side view of Figure 6, Figure 8 is a front view of a stationary reaction plate, Figure 9 is another embodiment of a friction plate embodying the invention, and Figure 10 is a side view of Figure 9.

Reference is now made to Figure 1 which illustrates a three dimensional partial section of a rotary actuator 11 embodying the invention. The basic components of the rotary actuator 11 are an input member in the form of an input through shaft 12 and an output member in the form of concentrically mounted output shaft 1 3. The input shaft 1 2 is supported in a three part housing made up of a pair of housing end sections 1 6 and 18 with a central actuator housing 1 7 secured as shown to the housing end sections 1 6, 1 8. The input through shaft 12 is supported at one end in housing end section 18 by ball bearing 19. A ball bearing 21 is disposed at the other end of input through shaft 12 between the input shaft 12 and the output shaft 13.The output shaft 13 is supported in housing end section 16 by ball bearing 22.

A planetary gear section 31 , the details of which can best be understood by a study of the schematic of Figure 2, couples the output shaft 13 through a ring gear 32, compound planet gears 33, 34, 33', 34' on carrier 35', fixed to housing 17 ring gear 36, and sun gear 37 secured to concentric shaft 38. The details of the differentiai planetary gear train do not form a part of the invention and will only be described in general terms insofar as its significance to the combination of components is concerned.

Concentric shaft 38 is connected to the disc brake arrangement 39 of the subject invention.

The details of the disc brake arrangement will be detailed hereinafter in respect of Figures 3, 4, 5 and 6. At this point in the description of a mechanical application in which the invention finds utility the disc brake 39 will only be briefly described.

The disc brake 39 of the invention includes brake plates 23, 24, 25, 26 and stationary plates 41 , 42, 43 secured as shown to central housing 17 as shown in Figure 1 and schematically illustrated in Figure 2. A splined section 46 of concentric shaft 38 carries the brake or friction plates 23, 24, 25, 26. An output plate 51 is formed integrally to the splined section 46 of concentric shaft 38. An input plate 52 is shown secured to a spline 53 on the input through shaft 12. Torque transmitting means in the form of balls, one of which 55 is shown, are disposed between the input plate 52 and the output plate 51. Each of the plates have a plurality of slightly elongated recessed regions, not shown, to accommodate the balls. The input plate 52, output plate 51 and the balls, one of which is shown in Figure 1, form what is termed a ball ramp torque limiter actuator. Before the operation of the ball ramp torque limiter actuator is described, it should be noted that the output plate 51 is biased or preloaded towards the input plate 52 by means of a helical compression spring 66. The arrangement now to be described can best be appreciated by a study of Figures 2 and 3. The spring 66 abuts at one end with adjustable nut 67, which nut is fitted on a threaded portion 68 of input through shaft 12, and at the other end with shaft washer 71.

The shaft washer 71 has positioned on its other side, needle thrust bearings 72 which are fitted flush against a shaft washer 73, which in turn abuts the end 74 of concentric shaft 38. It should also be observed that the preload that is transmitted from spring 66, washer 71, needle bearing 72, washer 73, concentric shaft 38, output plate 51, ball 54, and input plate 52 is resilientiy opposed by belleville washer pair 76, 77 shown located between the input plate 52 and a snap ring 75 which abuts roller bearing 19 secured to the end housing 1 8. The belleville washer pair 76, 77 provides sufficient axial force to maintain axial running clearance during normal operation. The input plate 52 is held in its axial location with respect to the shoulder of shaft 12 formed by the spline 53.This avoids the need to transmit spring 66 preload across a rotating interface, thereby avoiding a significant loss of efficiency.

Reference is again made to Figure 3 and Figure 4 to facilitate a comprehension of the energy absorbing no-back ratchet arrangement of the combination.

In Figure 4, the output plate 51 is shown in an exploded view to the right of planetary gear section 31. The input plate 52 is shown in its relative position, vis-a-vis, a ratchet ring 81 or ring means as it may be termed. The ratchet ring 81 has on its internal surface 82, a plurality of notches 83, 84, 85 and 86. The output plate 51 has thereon a pair of pawl members 87, 88, pivotally mounted on pins 89, 90. The pawl member 87 has a ratchet ring notch engaging portion 91 and in a like manner, the pawl member 88 has a ratchet ring notch engaging portion 92.

The pawl member 87 is biased toward the ratchet ring 81 by a leaf spring 93 secured to pin 94 and flexed over pin 95. Pins 94, 95 may be secured to output plate 51 in any suitable manner. The pawl 88 is likewise biased toward ratchet ring 81 by leaf spring 96 which leaf spring 96 cooperates with pins 97, 98. Pins 97, 98 may be secured to output plate 51 in any suitable manner.

The input plate 54 has integral therewith a pair of spaced apart release pins 101, 102. The release pins 101, 102 are positioned parallel to the axis of rotation of the input through shaft 12. Broken lines 103, 104 (Figure 4) indicate the mating engagement with pawl shoulders 78, 79 of pawl members 87, 88.

In Figure 1 and Figure 3, the manner in which the energy absorbing ratchet ring 81 is slidably frictionally secured between the central housing 1 7 and end housing 1 8 is shown. A wave spring washer 80 is disposed between the ratchet ring 81 and the end housing 1 8. Housing bolts, of which only one is shown as bolt 105 having a nut 106 threaded thereon, when torqued in place apply a resilient force through wave spring washer 80 to ratchet ring 81. The ratchet ring 81 may slide with the housing 17, 18 when sudden dynamic loads are transmitted back through the actuator 11 from the output shaft 13.

In respect of the general operation of apparatus just described, the details of Figure 1 will assist the reader in following the operation to be described.

Input torque and directional rotation are transmitted into the actuator 11 by means of the spline 10 on the input through shaft 12. Most of the torque input is carried down the center of the actuator 11 by the input through shaft 12. This torque is transmitted to additional aircraft shafting by the mating output spline 1 4 on the opposite end of the input through shaft 12. A portion of the input torque is removed from the input through shaft 12 and used to perfrom work culminating in movement of the aircraft slats (not shown). This torque is removed by means of a spline 53 on the input through shaft 12, which is attached to the input plate 52 of ball ramp torque limiter.Under normal operation this input torque rotates the three balls 55, 56 and 57 in the torque limiter along a small machined flat (not shown) at the bottom of the unreferenced recess regions in plate 51, ramps 62, 63. This transfers torque to the output plate 51 of the torque limiter. Rotation of the input plate 54 allows either pin 101, 102 of Figure 4 secured to the input plate 54 to depress either of the spring loaded pawls 87, 88 out of its no-back detent position. Under normal load conditions, the balls will not travel up the ramp, but will transmit torque to the output plate 51 of the torque limiter. The output plate 51 is integrally connected to the sun gear 37 by concentric shaft 38. Rotation of the output plate 51 transmits the input torque to the planetary.The sun gear torque is transmitted to the planet carrier 35 through the planet gears 33, 34 and 33', 34'. The input side of these planet gears 34, 34' react against a fixed ring gear 36, which results in movement of this carrier 35 around the actuator centerline as a result of carrier torque. The output side of the planet gears 33, 33' then transmit torque to the output shaft 1 3. The output shaft 1 3 is connected to the driven system through integral splines 1 5 on the output shaft 1 3.

During an overload or jam condition, the balls 55, 56, 57 in the torque limiter would climb the ramp, i.e., Figure Sb ramp 62 or ramp 63, as the preload induced by helical compression spring 66 is overcome. The travel of the balls up the ramp results in translation of the output plate 51 towards the not referenced brakeplates of disc brake 39. As the rotating brakeplates of disc brake 38 contact the stationary brakeplates 41, 42 and 43, the increasing torque on the output plate 51 is grounded to the actuator housing 1 7 and to the aircraft structure. The connection of housing 1 7 and the aircraft structure is not shown. At this point, all additional input torque is reacted into the housing 17, thereby limiting the output actuator torque.

In the event the drive shafting is broken or, for other reasons, does not react against a backdriving load, the normal inefficiency of the planetary system will prevent backdriving. If the inefficiency is not adequate to sustain the aiding load, as would occur in a vibratory operating mode, the actuator 11 provides for the reaction of any backdriving load through the energy absorbing arrangement of the pawls 87, 88 and friction mounted ratchet ring 81.

Reference is now made to Figure 5 where there is shown in partial section the essential elements of the friction brake arrangement of a disc brake, generally indicated by arrow 110. The disk brake 110 embodies the invention and it is to be understood that the disc brake 39 of Figure 1 would include the basic elements of the structure shown in Figure 5. It should also be understood that for purposes of explanation, not all of the structure shown in Figures 1 to 4 are present in Figure 5. Accordingly, wherever possible the reference numerals utilized in earlier figures will be employed to designate corresponding parts in Figure 5 and where appropriate in subsequent figures.

With the foregoing understood, in Figure 5 there is shown a pair of reaction or friction plates 111,112 mounted for axial movement on splined end portion 46 of tubular shaft 38. Friction plates 111,112 would correspond with friction plates 23, 24 of Figure 2. There is also shown mounted for rotation on splined end portion 46 of shaft 38 output plate 51. Not shown in Figure 5 are the friction plates that would correspond to friction plates 25, 26 of Figure 2. The output plate 51, it will be recalled, rotates with tubular shaft 38 and the entire tubular shaft 38, splined end portion 46 and the output plate 51 are mounted for axial movement as indicated by double headed arrow 116.Mounted snugly but yieldabiy movable in the friction plates 111, 112 are friction elements such as carbon buttons 113, 114. Positioned between the friction plates 111, 11 2 is a reaction plate 118 which is also axially movable and is stationary, i.e.

secured against rotation by means of bifurcated end projections 119 (see Figure 8) which cooperate with a bolt such as bolt 105 shown in Figures 2 and 3. A stop member 117 is shown schematically secured to schematically shown bolt 105. The friction plates 111, 112 have planar side surfaces as is indicated in Figure 7 by reference numerals 11 5, 11 5'. The friction elements have at opposite ends friction surfaces 120, 121, see Figure 7. In operation the friction surfaces 120, 1 21 simultaneously engage the reaction plate 11 8 and the stop member 11 7. The friction element 114 in friction plate 112 functions as a bearing in that the surface 122 bears against the output plate 51 to transmit axial movement to the stacked arrangement of reaction plates 112,118 and 111.The surface 123 of friction element 114 frictionally cooperates with the reaction plate 11 8. Braking occurs when the force on the output plate 51 causes the friction plates 111, 112 and the reaction plate 118 to be driven to the left against stop member 117.

In the preferred embodiment of the invention the friction elements 113, 114 are comprised of short cylinders of carbon or carbon buttons as they may be termed. The carbon buttons are placed in round holes in the friction plate 111 as shown in Fig. 6. In practice the carbon button would be a few thousandths thicker than the thickness of the friction plate. The friction plate can be made from almost any material that is strong enough to take the reaction load required by the break. In most cases, this material would be aluminum or steel, but it could be made of plastic.

By utilizing snugly but yieldably movable buttons that can be characterized as floating, which buttons are pressed into the friction plates the requirement for specific diameters on the brakeplates is eliminated since the carbon buttons can be placed into any diameter that will accommodate their diameter. For example, if 20 or 30 friction plates were desired, the backing material, i.e. the plate itself could be easily machined in a conventional manner. The carbon buttons then can be machined off of standard stock carbon rod, then lapped to the proper height and pressed into the holes in the friction plate which would result in a completed brake or friction plate. This would not require any special tooling or long lead times as one will find in normal brakeplates where tooling is required for the basic brakeplate and for the bonding of the brake material.

Since carbon is relatively compatible with many different kinds of lubricants and materials, the plate for the carbon buttons can be selected not based on its inter-reaction with the carbon, but on its inter-reaction with the greases and the other materials in the area. Again, this allows a very large selection of materials including plastics or even sophisticated composites.

It should therefore be apparent that the cost of the brakeplate will go down dramatically since the number of operations to make the brakeplate has been reduced. In an actual situation there have been found cost savings which amounted to twothirds the cost of the originally selected brakeplates of the prior art.

Since there is no bonding or mechanical connections of the buttons to the holding plate, inspection is not a difficult problem. The buttons can have a wide range of tolerances on their diameter to the hole fit in the plate and the only critical diameter is the actual height of the buttons which can be controlled reasonably from a standard hyperlapping operation. This should significantly reduce the rejection rate of brakeplates and also increase the confidence level, since they can be inspected.

It should also be appreciated that brakeplates themselves can also be reduced in thickness which results in a decrease in the size and weight of the brake package. This comes about because the carbon discs or buttons pass completely through the friction plate and only stick out a sufficient amount to assure clearance between the friction plate and the adjacent reaction plate. The benefit from this is that the carbon can be thicker than you would normally expect to have if you had to bond the carbon on the surface of the friction plate. A further advantage that flows from the invention arises whenever the carbon buttons wear down to the point where they are too thin.

When this occurs, it becomes very easy to replace the carbon buttons thereby obviating the need to replace the expensive friction plate or holding plate as it is sometimes referred.

While carbon is presently used, it is appreciated that the friction button could be formed of other materials such as bronze, teflon, etc.

Figures 9 and 10 illustrate another embodiment of the invention wherein friction plate 1 25 takes on a rectangular configuration as shown with only two friction elements 126,127 employed.

It is to be understood that the friction elements may be of any desired cross-section configuration.

In Figure 9, friction element 126 has a circular cross-section, while friction element 127 has a square cross-section. The friction plate 1 25 is also provided with thermal expansion slots 128, 129.

These thermal expansion slots 128, 129 may be positioned as shown, and are intended to provide relief from constructive forces that arise when the friction plate experiences very low temperature such as those that occur in the hostile environment of high altitudes when the invention may be employed.

It will be observed that the friction plate 125 has a rectangular opening 1 30 which is intended to cooperate with a support shaft not shown. The opening 130 could as well be of a splined configuration as is shown, but not referenced in Figure 6.

Claims (19)

1. An improved friction coupling device including a friction plate slidably secured to a rotatable shaft between a reaction member and an axially movable member, the friction plate having planar side faces and friction means mounted within the friction plate in a snug but yieldably movable manner to provide a pair of friction surfaces at opposite ends thereof, whereby the friction surfaces simultaneously engage the reaction member and the axially movable member to cause the frictional coupling of rotary movement of the rotatable shaft to the reaction member upon the application of an axial force to the axially movable member.

2. A friction coupling device according to claim 1, wherein the axially movable member has a planar surface adjacent to the friction plate.

3. A friction coupling device according to claim 1 or claim 2, wherein the friction plate is provided with a plurality of the said friction means each of which passes through the friction plate and is mounted within the friction plate in a snug but yieldably movable manner.

4. A friction coupling device according to any preceding claims, wherein the friction plate, the reaction member and the axially movable member each has an annular configuration.

5. A friction coupling device according to any preceding claim wherein the axially movable member is fast to the rotatable shaft which itself is axially movable in response to the axial force.

6. A friction coupling device according to any of claims 1 to 4, wherein slidably secured to the shaft is an array of similar friction plates alternating with similar axially movable members, so that the axial force from each axially movable member is transmitted to a next adjacent axially movable member through the intervening friction plate, where by the friction means simultaneously engage the axially movable members on opposite sides thereof to assist the frictional coupling of rotary movement of the rotatable shaft to the reaction member on the application of the axial force to the endmost axially movable member.

7. A friction coupling device according to any preceding claim, wherein the friction plate is provided with a plurality of the said friction means each of which has a uniform circular button shaped configuration.

8. A friction coupling device according to claim 7, wherein each of the said friction means if made of carbon.

9. A friction coupling device according to any preceding claim, wherein the friction plate is provided with at least one slot that extends from an opening in the friction plate to an edge that receives the friction means of the friction plate to allow for the dissipation of thermaily induced stresses on the friction means whenever the friction coupling experiences a wide range of temperatures during usage.

10. A friction coupling device according to any preceding claim, wherein the reaction member is stationary and the rotary movement of the rotatable shaft is braked upon the application of the axial force to the axially movable member.

11. Any of the friction coupling devices described herein with reference to the drawings.

12. An improved friction plate arrangement for use with a pair of relatively axially movable components the first component of which is stationary with respect to a second component, said second component is mounted such that a planar surface thereof moves in a plane parallel to a planar surface of said stationary component, a friction plate being disposed between said first and said second components and coupled to said second component; said friction plate having planar side surfaces parallel to said planar surfaces of said first and said second components; and said friction plate having a first friction means which passes through said friction plate and extends beyond both sides of said friction plate, said first friction means mounted within said friction plate in a floating manner to thereby provide a pair of friction surfaces at opposite ends of said first friction means, said floating first friction means friction surfaces are situated adjacent said first component and said second component planar surfaces such that said relative axial movement of said components causes said friction surfaces to said opposite ends of said first floating friction means to simultaneously engage said first stationary component and to be frictionally coupled to said second component and provide a braking force upon said parallel movement of said planar surfaces of said first and said second components.

13. The friction plate arrangement of claim 12 wherein there is included a third axial movable component disposed between said friction plate and said second component.

14. The friction plate arrangement of claim 1 3 wherein there is included another friction plate disposed between said third component and said second component, said other friction plate having a second friction means which passes through said other friction plate and extends beyond both sides of said friction plate, said second friction means mounted within said friction plate in a floating manner to thereby provide a first and a second surface at opposite ends of said second friction means, said first surface providing a friction surface situated adjacent said third component, said second surface providing a bearing surface adjacent said second component, whereby said axial movement of said first, second and third component causes said third component to frictionally couple said friction plate to said second component via said third component and said other friction plate.

1 5. The friction plate arrangement of claim 1 4 wherein said one and another friction plates are mounted for simultaneous rotary motion.

1 6. The friction plate arrangement of claim 1 5 wherein said first and said third components while axially movable are stationary with respect to rotary motion.

17. The friction plate arrangement of claim 1 6 wherein said first and said function means each have a uniform circular button shaped configuration.

1 8. The friction plate arrangement of claim 1 7 wherein said first and said second friction means are made of carbon.

19. The friction plate arrangement of claim 12 or 1 8 wherein said friction plate is provided with at least one slot that extends from an opening that receives said friction means in said friction to an edge of said friction plate to thereby allow for the dissipation of thermally induced stress on said friction means whenever said friction coupling experiences a wide range of temperatures during usage.