FR2526900A1 - DEVICE FOR FRICTION COUPLING AND ASSEMBLY OF FRICTION PLATES - Google Patents

Abstract

THE INVENTION RELATES TO A PERFECTED FRICTION COUPLING DEVICE. THE DEVICE 110 INCLUDES AT LEAST ONE FRICTION PLATE 111, 112 THROUGH WHICH A FRICTION ORGAN 113 OR 114 IS CLOSELY MOUNTED, WHICH CAN HOWEVER BE MOVED SOFTLY. THE PLATES 111, 112 ARE MOUNTED BETWEEN A FIXED ELEMENT 117 AND AN ELEMENT 51, AXIALLY MOBILE WHICH, WHEN IT IS CLOSED TO THE ELEMENT 117, CAUSES THE TIGHTENING OF THE PLATES 111, 112 AGAINST A REACTION PLATE 118 AND AGAINST THE FIXED ELEMENT 117, SO AS TO PRODUCE A BRAKING FORCE. FIELD OF APPLICATION: BRAKES AND CLUTCHES FOR AIRCRAFT GOVERNING SHAFTS.

Description

The invention relates to an improved device

friction plate brake.

  Rotating friction clutches and brakes have been the subject of constant technological improvements over the last century, as new materials and manufacturing techniques have led to the development of new friction materials and processes. material fixation The creation of new long-life friction materials with desirable friction characteristics has prompted the industry to find new ways of bonding

  or attach the materials to general friction plates

  used in brakes and rotary friction clutches It was widely recognized that early use of friction brakes and clutches, solid carbon friction elements would be used shortly afterwards.

  the beginning of the century, the need for an automatic clutch

  lubricant has imposed the use of graphite blocks fixed in clutch linings in order to cooperate

  with the metal face of a driving or driven element.

  U.S. Patent No. 804,104 is representative of the utility recognized in the past by

  of a carbon form to form a friction element.

  As described in this patent, a simple general friction surface is produced by inserting carbon blocks in the face of a disk. The invention as described below provides an improvement to this area by doubling the surface area of the surface. friction usable by mounting carbon buttons, floating,

  in a reaction element of a friction device.

  The use of button-shaped friction elements has also found utility in the design of the friction elements. US Pat. No. 1,655,827 uses, about twenty years later, shaped inserts. of buttons mounted in a brake element, the buttons being made of asbestos fibers held by a binder to form the buttons The inserts 11 asbestos and binder wire (Figures 3 and 4 of the aforementioned patent No. 1,655,827) are placed in openings 12 of a disc 10 The attached members 11 are cut to a length such that they protrude laterally over the desired distance from the faces of the disc 10, and they are then subjected to

  longitudinal pressure exerted on their opposite ends

  which has the effect of driving them back into

  milling, as shown in Figure 4, and the

  The invention as hereinafter described achieves several friction surfaces for each insert member while at the same time eliminating the mechanical operation required in the abovementioned patent No. 1,655,827 to fix the reported organs

to the support disk.

  The fact that it is desirable to double the usable friction surface for each button or insert is also recognized in the clutch described in the patent No. 2,054,872 in the figure which can be seen that the friction members 26 reported in

  cork are placed in openings 25 of a disk 20.

  The organs reported in cork, which have been soaked in

  water, are compressed in order to pass through the openings

  tures 20 of the disk 20, after which they expand to rigidly attach themselves to the disk 20 as shown in FIG. 1a. Although it is recognized in the above-mentioned patent No. 2,054,872 that have multiple friction surfaces on the inserts

  26 cork, no dynamic advantage emerges from the use of

  the use of a mounted friction fitting mounted

  elastically, in a disk

  as described in more detail below.

  A few years later, the United States patent

  United States No. 2,421,925 also recognizes the desirability of using multiple friction surfaces. FIG. 3 of this patent shows frusting members 27 made of porous metal and tightly fitted in a disc 16, then fixed position in this disc 16 It is also not suggested the use of a friction member mounted tightly, but movable in a flexible manner, as it is

the case of the present invention.

  U.S. Patent No. 2,924,314 is interesting in that it discloses a transmission

  intermittent action in which an electronic clutch

  12 and a brake 14 seem, at first glance, to present a technique with floating element 55 of friction in a reaction disk 40 which seems to be of a structure similar to that of the friction member mounted closely, but movable However, a detailed examination shows that the reported friction floating member described in US Pat. No. 2,924,314 is made of a magnetic material which is attracted to an electromagnetic coil 24 of the present invention. clutch or to a magnetic brake coil 56 so as to have a single friction surface in one or other of the operating modes, using the clutch or the brake, of the intermittent transmission. It is not suggested in the aforementioned US Pat. No. 2,924,314, the use of a friction floating insert in a reaction plate, which co-operates simultaneously with two friction surfaces, one of which has at least one is brought into contact with a movable friction mounted member carried by the plate of

  reaction, as described more fully hereinafter.

  The idea of linking or fixing the buttons made of metal compositions on a metal disk is widespread. US Pat. No. 3,937,303 describes such a method and illustrates it in particular in FIGS. 1 and 2. fixing buttons

  to a disk 11 and the mechanical problems that

  when one or more fixed buttons are detached during service are deviating from this method when factors such as low cost and longevity are of primary importance The invention described below satisfies these desirable factors, of a

  particularly interesting way.

2526900-

  The prior art is also illustrated by US Pat. No. 3,986,588, which relates to a brake-clutch assembly for a winch. The important role of positioning friction buttons 96 in a plate 54. (snap) (FIG. 2) so that they can rotate freely and they are mounted with a sufficient clearance, with respect to the associated hole, so that a moderate axial translation is possible in order to make up for surface irregularities or defects. However, each friction button described in the latter patent must include a head 100 preventing the buttons 96 to pass through the plate 54 and thus to offer to each several friction surfaces as is the case of the invention which will now be described. An improved friction coupling device includes a reaction plate slidably mounted on a rotating shaft to frictionally couple to a

  The friction plate has lateral surfaces

  The Friction Coupling Device

  includes, in combination with the reaction plate, the

  said first side of the reaction plate, and an axially movable member disposed on the other side of the reaction plate. The latter has friction members which pass through the reaction plate and protrude from the surfaces of the reaction plate. The friction members are mounted in the reaction plate in a narrow, but resiliently movable manner, so that the opposite ends of these

  friction members have two friction surfaces.

  These last ones simultaneously bear against the first

  cited element and the axially movable element in order to trans-

  frictionally put the rotary motion of the

  to the first element when applying a force

  axial to the axially movable member.

  In the preferred embodiment, the arrangement

  The friction coupling is a brake and the first element is fixedly held so that it can not rotate. The subject of the invention is therefore a reaction plate intended to be used in a brake or in a

  a clutch, this reaction plate comprising

  friction ganes which pass therethrough and which are mounted in this plate in a narrow but flexible manner so as to present at their opposite ends two surfaces

friction.

  The subject of the invention is also a device

  improved friction coupling in which the element

  It is another object of the invention to provide a reaction brake plate having friction members,

  this brake plate being of low cost, of

  easy assembly and easy assembly.

  In order to achieve the aforementioned objectives, it is provided according to the invention that the improved reaction plate, also hereinafter referred to as the friction plate or the brake plate, is used with two members movable axially relative to one another. other The first member is fixed so as not to be rotatable relative to the second member The latter is mounted so that its

  flat surface moves in a plane parallel to an over-

  flat face of the fixed member A friction plate is disposed between the first and second members and is

coupled to the second organ.

  The friction plate has flat surfaces parallel to the planar surfaces of the first and second members. The friction plate has at least one first friction element which passes therethrough and protrudes from both sides of this plate. The first friction element is mounted inside the friction plate in a floating manner so as to present, at its The friction surfaces of the first element are adjacent to the planar surfaces of the first and second members so that the relative axial movement of the members has the effect, on the friction surfaces of the opposite ends of the floating element friction, simultaneously make them bear against the first fixed member and establish a coupling by

  friction with the second member The assembly described above

  Above exerts a braking force on the movement

  parallel plane surfaces of the first and second bodies.

  In the preferred embodiment of the invention,

  A third movable axial member is provided between the friction plate and the second member. The preferred embodiment of the invention further comprises another friction plate disposed between the third member and the second member. friction also comprises a second friction element of the same type and of the same embodiment as the first-friction element Therefore, the second friction element

  present, at its ends, first and second sur-

  friction faces The first friction surface of the second member is adjacent to the third member The second friction surface of the second member constitutes a surface

  adjacent the second member so that the movement

  of the first, second and third members causes frictional engagement of the friction plate with the second member via the

  third member and the other friction plate.

  In addition, in the preferred embodiment of the invention, the friction elements are made

  carbon and are of uniform circular section.

  The invention will be described in more detail with reference to the accompanying drawings by way of non-limitative examples and in which: FIG. 1 is a perspective view, partly in section, of a rotary actuator comprising the improved friction device according to FIG. 'invention;

  FIG. 2 is a diagram of the rotary actuator

  tif of Figure 1; FIG. 3 is a partial longitudinal section of the rotary actuator of FIG. 1; FIG. 4 is an exploded perspective view, partly in section, of a differential planetary reduction gear associated with a non-return snap which cooperates with the device; improved friction according to the invention;

  FIG. 5 is a longitudinal section through

  a disk brake according to the invention; Figure 6 is a front view of a friction plate according to the invention; Figure 7 is an elevation of the plate of Figure 6; Figure 8 is a front view of a fixed reaction plate; Figure 9 is a front view of another

  embodiment of a friction plate according to the invention.

  vention; and Figure 10 is an elevation of the plate

of Figure 9.

  Referring now to FIG.

  In perspective, with partial section, a rotary or rotary actuator 11 according to the invention. The main elements of the rotary actuator 11 comprise an input element in the form of a shaft.

  through 12, and an output element is

  in the form of a mounted output shaft 13

  The input shaft 12 is mounted in a three-part housing consisting of two end portions 16 and 18 fixed, as shown, to a central casing 17 of the actuator. end, in the end portion 18 of the housing, by a ball bearing 19 A ball bearing 21 is disposed at the other end of the input shaft 12, between

  the latter and the output shaft 13 This is worn.

  in the end portion 16 of the housing by a ball bearing z 2.

  A planetary gear 31, the details of which appear more clearly in the diagram of FIG. 2, connects the output shaft 13 to a concentric shaft 38 via a ring gear 32, compound planet gears 33, 34, 33 ', 34' arranged on a support 35 'fixed to the housing 17, a ring gear 36 and a sun gear 37 fixed to the concentric shaft 38.

  The details of the differential planet gear do not

  not within the scope of the invention and this gear is described only in a general way in the measure

  importance for the assembly of the elements of the in-

vention.

  The concentric shaft 38 is connected to the disc brake assembly 39 according to the invention. This assembly will be described in more detail below with reference to the figures

  3, 4, 5 and 6 At this stage of the description of an application

  mechanical system to which the invention is useful, the

  Disc brake 39 will be described only briefly.

  The disc brake 39 according to the invention comprises brake plates 23, 24, 25 and 26 and fixed plates 41, 42, 43 secured, as shown, to the casing

  17, as shown in FIG.

  Figure 2 A splined section 46 of the concentric shaft 38 carries the brake or friction plates 23, 24, 25 and 26. An outlet plate 51 is made in one piece with the splined portion 46 of the concentric shaft 38 An inlet plate 52 is shown as being attached to a rib 53 of the input through shaft 12. Torque transmission means in the form of balls, one of which is shown at 55, are arranged between the inlet plate 52 and the outlet plate 51 Each plate has a plurality of recessed, slightly elongated zones (not shown) for accommodating the balls. The inlet plate 52, the

  outlet plate 51 and the balls, one of which is

  1, form what is called a front-end ball-bearing torque limiting actuator

  to go on to describe the operation of the action-

  It should be noted that the output plate 51 is biased or preloaded to the input plate 52 by a compression coil spring 66. The assembly which will now be described may be better appreciated. FIGS. 2 and 3 show the spring 66 abuts at one end against an adjustable nut 67 which is mounted on a threaded portion 68 of the input through shaft 12, and at its other end against a washer 71 of Axial thrust bearings 72 are disposed on the other side of the shaft washer 71 and are arranged against a

  shaft washer 73 which, itself, stops against the end

  mite 74 of the concentric shaft 38 It can also be observed that the preload transmitted by the spring 66, the

  washer 71, the needle stop 72, the washer 73, the

  concentric head 38, outlet plate 51, ball 55

  and the input plate 52, meets an elastic resistance

  tick opposite it by two Belleville washers 76 and 77 which are represented as being arranged between

  the input plate 52 and an elastic ring 75 mounted

  in abutment against a ball bearing 19 fixed to the end casing 18 The two Belleville washers 76 and 77 exert an axial force sufficient to maintain an axial backlash during normal operation The inlet plate 52 is maintained in its axial position relative to at the shoulder of the shaft 12 formed by the

  rib 53 This avoids having to transmit the pre-

  charge of the spring 66 by a rotating interface, which

  avoids a significant loss of yield.

  Reference is now made to Figures 3 and 4 for

  an easier understanding of the functioning of the

  anti-reverse absorption of energy absorption.

  FIG. 4 shows the exploded perspective output plate 51 towards the right of the planetary gear 31. The input plate 52 is represented in FIG.

  the relative position with respect to a snap ring 81

  The inner surface 82 of the snap ring 81 has a plurality of notches 83, 84, 85 and 86. The outlet plate 51 carries two pawls 87 and 88 which pivot on pins 89 and 90. part 91 intended to engage in a notch of the snap ring and, in a similar manner, the pawl 88 has a portion 92

  intended to engage in a notch in the ring of

  The pawl 87 is biased towards the locking ring 81 by a leaf spring 93 fixed to an axis 94 and bent on an axis 95. The pins 94 and 95 can be fixed to the outlet plate 51 in any suitable manner. pawl 88 is biased in the same way towards the locking ring 81 by a leaf spring 96 which cooperates with pins 97 and 98 These can be fixed to the plate 51 output

in any suitable way.

  The input plate 52 is made of a single

  piece with two fingers spaced 101 and 102 release.

  These fingers 101 and 102 are arranged parallel to the axis of rotation of the input shaft 12 The dotted lines 103 and 104 of FIG. 4 indicate the engagement with shoulders 78 and 79 of the pawls

87 and 88.

  FIGS. 1 and 3 show how the energy absorbing snap ring 81 can slide frictionally between the central casing 17 and the end casing 18 which hold it up. A spring-loaded corrugated washer 80 is disposed between the ring 81 detent and the extreme housing 18 Crankcase bolts, only one of which is shown at 105, a nut 106 being screwed

  on this bolt, apply an elastic force, through

  middle of the wave washer 80 spring at the ring

  81 snap, when tightened in position.

  The snap ring 81 can slide with the casing 17, 18, when sudden dynamic loads are

  returned from the output shaft 13 through the actuator 11.

  With regard to the overall operation of the apparatus just described, the details of FIG. 1 help to follow the mode of operation as described below. An input torque and a determined directional rotation are transmitted in the actuator 11 by means of

  of the splined section 10 of the input shaft 12.

  The majority of the input torque is applied to the center of the actuator 11 by the input shaft 12. This torque is transmitted to other shafts of the aircraft or aircraft by the splined section 14 of the output. Coupling located at the opposite end of the input shaft 12 A portion of the input torque is taken from the input traversing shaft 12 and used for the execution of a work resulting in a movement of the flaps of the leading edges of the aircraft (not shown) This torque is taken at

  means of a splined section 53 of the through shaft of

  12, this section being connected to the input plate 52 of the ball-rail torque limiter. In normal operation, the input torque rotates the three balls 56, 57 of the torque limiter along a small distance. machined flat surface (not shown) located at the bottom of the unreferenced recessed areas of the plate 51 and on the ramps This results in a torque transfer to the output plate 51 of the torque limiter The rotation of the input plate 52 allows at one or other of the fingers 101 and 102 (Figure 4), fixed to the input plate 52, to lower one or other of the pawls 87 and 88 to recall

  by spring in order to disengage it from its

  In normal load conditions, the balls do not run through the ramps, but transmit

  a torque at the output plate 51 of the torque limiter.

  The outlet plate 51 is secured to the flat wheel

  37 by the concentric shaft 38 A rotation of the

  51 output plate transmits the input torque to the en-

  Planetary gearing The torque of the sun gear is transmitted to the carrier 35 via the planet gears 33, 34 and 33 ', 34'. The input side of the planet gears 34, 34 'reacts against a stationary gear 36, which which results in a displacement of the support 35 around the central axis of the actuator as a result of the support torque. The output side of the planet gears 33, 33 'then transmits a torque to the output shaft 13 which is connected to the mechanism led by the splined section 15 made in one piece with the shaft

13 out.

  In case of overload or jamming, the balls, 56 and 57 of the torque limiter rise on one or the other of the ramps when the preload of the coil spring 66 of compression is overcome The movement of the balls rising along the ramps results in a translation of the output plate 51 to the brake plates, not referenced, of the disc brake 39. When the disc brake rotatable plates 39 bear against the fixed plates 41, 42 and 43 of the brake, the torque increasing, applied to the output plate 51, is transmitted to the mass of the casing 17 of the actuator and the structure of the aircraft The connection with the casing 17 and with the structure of the aircraft is not shown A at this stage, the housing 17 reacts to the entire input torque, thus limiting

  the output torque of the actuator.

  In the case where a drive shaft is broken, or if, for any other reason, it does not react to a

  charge back, the normal inefficiency of the planetary system

  not pay for any training in return If the inefficiency

  cited is not suitable for maintaining the assistant load, as can occur in a vibratory mode of operation, the actuator 11 opposes the reaction to any return charge by the energy absorbing device

  constituted by the pawls 87 and 88 and the ring 81 of

ratcheting frictionally mounted.

  Referring now to FIG.

  partially cut through the essential elements of the friction brake device of a disc brake

  110 in all. The corresponding 110-disc brake is

  to an embodiment of the invention and it should be noted that the disc brake 39 of FIG.

  includes the basic elements of the structure

  It should also be noted that FIG. 5 does not completely represent the structure shown in FIGS. 1 to 4, for the sake of clarity. Therefore, the same reference numerals as those used in the preceding figures are used. in

  wherever possible, to designate elements corresponding to

  of Figure 5 and the following figures when

this is appropriate.

  Given the above explanations, FIG. 5 represents two reaction or friction plates

  111 and 112 mounted so as to be able to move axially-

  on an extreme fluted section 46 of a tubular shaft

  The friction plates 111 and 112 correspond to the friction plates 23 and 24 of Fig. 2. Fig. 5 also shows an output plate 51 rotatably mounted with the fluted end portion 46 of the shaft 38 on which it is mounted The friction plates corresponding to the plates 25 and 26 of Figure 2 are not shown in Figure 5 It should be remembered that the output plate 51 rotates with the tubular shaft 38 and the whole of the tubular shaft 38, the fluted end portion 46 and the outlet plate 51 is mounted so as to be able to perform a

  axial movement as indicated by the double arrow 116.

  Friction elements such as carbon buttons 113 and 114 are mounted tightly, but resiliently, in the friction plates 111 and 112. A reaction plate 118, disposed between the friction plates 111 and 112, can also move axially and is fixedly held, that is to say so as not to be able to rotate, by means of projections

  fork-shaped extremities 119 (see Figure 8) which co-

  with a bolt such as the bolt shown at 105 in Figures 2 and 3 A stop 117 is shown schematically as being fixed to the bolt 105, also shown schematically The friction plates 111 and 112 have flat side surfaces as indicated by the references 115 and 115 'in FIG. 7 The friction elements have, at their opposite ends, friction surfaces 120 and 121 (FIG. 7). In operation, the friction surfaces and 121 simultaneously bear against the reaction plate 118 and against the abutment 117 The friction element 114 of the plate 112 assumes the function of a support in that the surface 122 bears against the outlet plate 51 in order to transmit the axial movement to the surface.

  The surface 123 of the friction element 114 frictionally engages with the reaction plate 118. Braking occurs when the force applied to the outlet plate 51 causes the drive plates to be driven. friction 111 and 112 and the reaction plate 118 to the left, to make them

bear against the stop 117.

  In the preferred embodiment of the invention,

  The friction elements 113 and 114 consist of short carbon cylinders, also known as carbon knobs. These are placed in round holes in the friction plate 111 as shown in FIG. carbon has a thickness greater than a few hundredths of a millimeter to the thickness of the friction plate The latter

  can be carried out in practically any

  resistant to withstand the reaction load imposed by the break In most cases, this material is aluminum or steel, but it can

be a plastic material.

  By using closely but elastically movable buttons which can be considered as floating, which buttons are force-fitted into the friction plates, the need to give the brake plates of the determined diameters disappears, since the carbon buttons can be placed in any hole suitable for their diameter For example, if one wishes twenty or thirty friction plates, the support material, that is to say the plate itself, can be machined in a conventional manner. carbon can then be machined by cutting into a normal carbon bar, then lapped at the appropriate height and press-fitted into the holes of a friction plate to obtain a completed brake or friction plate.

  does not require any special tools or

  aunt as is the case with normal brake plates for which tooling is necessary for the realization of the base plate and the binding of the material

braking.

  Since carbon is relatively

  tible with many different types of lubricants and materials, one can choose which plate to wear

  the carbon buttons, not according to its

  action with carbon, but depending on its

  action with grease and other materials in the vicinity As before, this allows to choose from a very wide range of materials, including plastics or even sophisticated composite materials. It therefore appears that the cost of the brake plate decreases significantly due to the decrease in the number of

  of operations involved in the manufacture of the plate.

  In the current situation, cost savings amounting to two-thirds of the cost of

  brake chosen initially in the prior art.

  Due to the absence of mechanical connections or fastenings of the buttons to the plate carrying them, the inspection does not pose any difficult problems The tolerances concerning the diameter of the buttons for their adjustment in the hole of the plate can be wide and the only diameter critical is the actual height of the knobs, which can be reasonably adjusted by a conventional burn-in operation. This significantly reduces the rejection rate of the brake plates and also increases the level of

  trust because they can be inspected.

  It should also be noted that the brake plates themselves can also have their thickness

  reduced, resulting in a decrease in the

  This results from the fact that the carbon disks or knobs pass completely through the friction plate and protrude only a sufficient distance to ensure clearance between the friction plate and the reaction plate. This has the advantage of allowing the carbon to have a greater thickness than it would normally have if it were to be bonded to the surface of the friction plate. Another advantage of the invention appears when the carbon buttons are use to the point of becoming too thin

  it is very easy to replace the buttons on the

  bone, which avoids having to replace the expensive plate

  friction or support, as it is sometimes referred to.

  Although carbon is currently used, it should be noted that the friction button may be formed of any other material such as bronze, "Teflon", etc. Figures 9 and 10 show another embodiment of the invention in which a friction plate has a rectangular configuration as shown, with only two friction elements 126

and 127.

  It should be noted that the friction elements

  may have, in section, any desired configuration.

  In FIG. 9, the friction element 126 has a circular section, while the friction element 127 has a square section. The friction plate 125 also has thermal expansion slots 128 and 129. These slots 128 and 129 can be located as

  represented and they are intended to

  The internal forces that occur when the friction plate is subjected to very low temperatures such as those existing in the hostile environment of high altitudes, where the invention can be used. It can be seen that the friction plate 125 has a rectangular opening 130 which is intended to

  to cooperate with a support shaft not shown

  vertex 130 might as well have a configuration

  fluted, as shown, without reference, in FIG.

Claims (14)

  A friction coupling device comprising a reaction plate (111 or 112) mounted to   able to slide on a rotating shaft in order to be accom-   frictionally adhered to a member (117), said reaction plate having planar side surfaces (115, ') and the friction coupling device being characterized in that said member is disposed on a first side of the reaction plate and an axially movable member (51) is disposed on the other side of the reaction plate, the latter carrying friction members (113, 114) therethrough and protruding from its flat lateral surfaces, friction being mounted tightly in the reaction plate but   in order to be able to move elastically, in order to   ter two friction surfaces (120, 121) at their opposite ends, these friction surfaces carrying simultaneously   against said element (117) and said axial movable element   for frictionally coupling rotational motion of the rotating shaft to said member (117) upon application of an axial force to said member axially movable.   2 Device according to claim 1, characterized in that the movable element has a flat surface   adjacent to the reaction plate.   3 Device according to claim 2, characterized in that the reaction plate comprises a plurality of friction members each passing through said plate and mounted: closely in the latter, but in a movable manner elastically -   4 Device according to claim 3, characterized in that the reaction plate has an annular shape which corresponds to an annular shape of said element (117)   and said axially movable member.   5 Device according to claim 4, characterized in that the rotating shaft to be braked can be moved   axially and is connected to the movable element, the rotating shaft   reacting to said axial force by effecting a motion corresponding to that of the movable member   when the axial force is applied.   6 Device according to claim 5, characterized in that the friction members each have a uniform circular button configuration. Device according to claim 6, characterized   in that the friction members are made of carbon.   8 Device according to one of claims 1   and 7, characterized in that the reaction plate 125 pre-   at least one slot (128, 129) which starts from an opening   formed in the plate and which terminates at an edge, this opening being intended to receive a friction member (126 or 127) and the slot for the dissipation of heat-induced stresses in the friction members when the friction coupling is subjected during service, at temperatures varying wide beach.   9 Device according to one of claims 1   and 7, characterized in that said element (117) is stationary and in that the rotational movement of the rotating shaft is braked upon application of an axial force to the moving element.   A friction plate assembly for use with two axially movable members relative to one another, the first member (117) being fixed relative to the second member (51) which is mounted to have a flat surface moving in a plane parallel to a flat surface of the fixed element,   a friction plate (111) being disposed between the first and second   first and second elements and being connected to the second element, the assembly being characterized in that the friction plate has plane lateral surfaces (115, 115 '), parallel to the plane surfaces of the first and second   elements, the friction plate comprising a first   a friction shaft (113) extending therethrough and protruding on both sides of said plate, the first friction member being mounted in the plate in a floating manner   so that its opposite ends have two surfaces-   friction members (120, 121) adjacent to the planar surfaces of the first and second members so that said movement   The relative axial axis of the latter has the effect of   friction faces at opposite ends of the first   first floating friction member simultaneously causing them to come into contact with the first fixed element and their friction coupling with the second element, and producing a braking force during said parallel movement of the plane surfaces of the first and second elements.   Assembly according to claim 10, characterized   characterized in that it comprises a third axially movable element (118) arranged between the friction plate and the second element.   Assembly according to claim 11, characterized   in that it comprises another friction plate (112) disposed between the third element and the second element and comprising a second friction member (114) which passes therethrough and which projects on both sides of this friction plate the second friction member being mounted in the friction plate in a floating manner to present, at opposite ends thereof,   first and second surfaces which constitute a   a friction surface adjacent to the third member and a bearing surface adjacent to the second member so that axial movement of the first, second, and third members acts on the third member to frictionally couple the friction plate to the second member by the second member; intermediate of said third element and the other friction plate.   Assembly according to claim 12, characterized   in that the first mentioned friction plate and the other friction plate are mounted so as to rotate simultaneously.   Assembly according to claim 13, characterized   rised in that the first and third elements, well   that mobile axially, can not rotate.   Assembly according to claim 14, characterized   rised in that the first and second friction members   each have a uniform circular button configuration.   Assembly according to claim 15, characterized   rised in that the first and second friction members are made of carbon.   Assembly according to one of the claims 10   and 16, characterized in that the friction plate (125) has at least one slot (128, 129) which extends from an opening receiving the friction member (126, 127) to an edge of said plate to allow the dissipation of thermally induced stresses in the friction member when the friction coupling is subjected, during operation, to temperatures varying in a wide beach.