GB2249595A - A method and apparatus for manipulating a friction clutch sub-assembly - Google Patents

Abstract

A clutch sub-assembly comprising a friction plate (2) and a clutch mechanism, which have been stored together, is manipulated so that it can then be assembled with the rest of the clutch. The friction plate (2) has friction pads (23) and a hub (21) with an internal bore, while the clutch mechanism comprises a cover (31) having a fastening flange (39), a declutching means (32, 41) and a pressure plate (33). The sub-assembly is supported in apparatus comprising a jig in the form of a support member (55) and a centring mandrel (80). The friction plate (2) and the clutch mechanism are mounted successively in the support member (55), which has an abutment surface (58) against which the fastening flange (39) of the cover member (31) bears. The mandrel (80) has a portion which engages in the bore of the hub (21) and the mandrel cooperates with a locking or support tool (70). A tool (50) is subsequently used to centre the cover and mount the mechanism on a reaction plate. <IMAGE>

Description

2249595 1 A METHOD AND APPARATUS FOR MANIPULATING A CLUTCH SUBASSEMBLY

COMPRISING A FRICTION WHEEL AND CLUTCH MECHANISM This invention relates to methods and apparatus for manipulating a clutch sub-assembly comprising a friction wheel and a clutch mechanism, during the manufacture of a motor vehicle, the apparatus comprising a jig for holding the components of the sub-assembly, and the method being a method in which such a jig is used.

In order to understand the background of the invention, it will first be convenient to describe a motor vehicle clutch of a conventional type. In this connection reference is made to Figures 1 to 3 of the accompanying drawings. Brief introductions explaining what these Figures represent are given later in this description.

With reference therefore to Figures 1 to 3, a motor vehicle clutch includes a reaction plate 1, which is fastened by means of suitable fasteners 5 (usually screws or studs) to the crankshaft 6 of the internal combustion engine of the vehicle; together with a clutch friction wheel 2 and a clutch mechanism 3. The mechanism 3 includes a pressure plate 33 (see Figure 2), and a cover member 31 having a fastening flange 39 by which the clutch mechanism 3 is adapted to be secured to the reaction plate 1 by means of suitable fasteners 7 (again, usually screws or studs) which extend through holes formed in the flange 39, with centring pins or dowels 8, carried by the reaction plate 1, being interposed.

The clutch mechanism 3 in Figure 1 is of the "Push to disengage" type, and includes a diaphragm 132 which is part of the declutching means of the clutch, and which is mounted for tilting movement in the cover member. A clutch 2 release bearing 4 is arranged to act in a thrust mode on the ends of the fingers of the diaphragm, so as to actuate the declutching means from its position in which the clutch is engaged to that in which the clutch is disengaged.

The clutch mechanism may equally well be of the "pull to disengage" type, and Figure 2 illustrates such a mechanism at 30. In this case, the outer periphery of the diaphragm, 32, engages on the cover member 31, and the clutch release bearing 40 is arranged to act in traction on the declutching means of the clutch so as to change the latter from its position in which the clutch is engaged to that in which the clutch is disengaged.

As can be seen in Figure 3, the friction wheel 2 commonly includes a hub 21 with a splined internal bore 28 for coupling the hub in rotation with the input shaft of the gearbox of the vehicle. The friction wheel also carries friction pads 23 which are arranged to be gripped between the reaction plate 1 and the pressure plate 33, so that the clutch can then transmit rotary"motion from the crankshaft to the gearbox input shaft.

When the clutch mechanism 3 or 30 is being fitted on the reaction plate 1, the clutch mechanism is initially in its warehousing or storage configuration. In order to secure the fasteners 7 to the reaction plate 1, it is necessary to constrain the diaphragm 32 or 132, with the pressure plate 33 coming into contact with the friction wheel 2. This causes parasitic frictional effects between the fasteners 7 and the cover member, such that (and particularly when the fasteners 7 are in the form of screws or studs), the heads of the fasteners are not always necessarily at the same height when they are screwed into place with a given torque. It follows that the cover member 31 may become i 3 deformed, and that the ends of the fingers of the diaphragm are not always necessarily in the same plane. This leads to the occurrence of vibrations, which are then transmitted through the clutch release bearing to the clutch pedal of the vehicle.

In order to overcome this drawback, it is possible to conceive of manoeuvring the declutching means of the clutch so as to put the latter into its "clutch disengaged" position. This leads to the use of a press tool or anvil, which enables the cover member to be applied to the reaction plate 1, and which also enables the diaphragm to be constrained as required. However, the applied force is transmitted through the crankshaft bearing of the vehicle, which can be detrimental. In no case is any arrangement provided for the purpose of manipulating the sub- assembly that consists of the friction wheel and clutch mechanism into any kind of special configuration such that this subassembly can then be fitted in its declutched O'clutch disengaged") position. Fitting is conventionally carried out using a suitable centring device, with the clutch mechanism and the friction wheel being stored separately prior to being fitted.

An object of the present invention is to overcome these drawbacks, and to provide a manipulating apparatus or jig which then enables the declutching means of the clutch to be manoeuvred in such a way as to assemble the cover member to the reaction plate without having to exert significant forces, thus, in particular, avoiding the application of such forces to the crankshaft bearing.

According to the invention in a first aspect, there is provided a jig for use during manufacture of a motor vehicle to manipulate a sub-assembly comprising a clutch 4 friction wheel and a clutch mechanism, the friction wheel having friction liners and a hub defining an internal bore, and the clutch mechanism being a unit comprising a cover member having a fastening flange, a declutching means engaging on the cover member, and a pressure plate coupled to the cover member for rotation therewith but being movable axially with respect thereto, wherein the jig comprises a support member adapted for the friction wheel and clutch mechanism to be successively inserted therein, together with a centring member or mandrel for centring the friction wheel in the said support member, the said support member having an abutment surface for engagement of the fastening flange of the cover member therewith, and the centring mandrel being adapted to cooperate with a locking tool and comprising a first portion for engagement in the bore of the said hub.

According to the invention in a second aspect, there is provided a method of manipulating a sub-assembly comprising a clutch friction wheel and clutch mechanism, using a jig according to the invention in its said first aspect, wherein a press tool is engaged on the cover member of the clutch mechanism so as to press the fastening flange of the cover member into contact with the abutment surface of the support member of the jig, and wherein an actuating tool is applied on either the centring mandrel or the declutching means of the clutch, whereby to manoeuvre the declutching means so as to shift it from its storage configuration to its declutching configuration.

Using the method and/or apparatus in accordance with the invention, the fitting of the clutch cover member is greatly simplified, and parasitic frictional effects between the fasteners and the cover member are reduced, as are any deformations of the cover member. In addition, the length of the fasteners is able to be reduced, and storage problems are simplified because the friction wheel and the clutch mechanism are handled together. Also, the various tools used may all be part of a single head for a robot, so that automated handling and fitting of the assembly is facilitated.

It will be appreciated that, besides the advantage of sparing the crankshaft bearing from the application of unwonted applied forces, the friction wheel is centred in contact with the pressure plate through the centring mandrel after the declutching mechanism of the clutch has been put into its declutching configuration.

The robot head preferably includes a locking tool, which is preferably of an expandable type and which in all cases centres the friction wheel in contact with the pressure plate, through the centring mandrel.

According to a preferred feature of the invention, the centring mandrel further includes a second portion for acting on the declutching means of the clutch, whereby the centring mandrel also acts as a declutching means.

The centring mandrel can be made very simple in shape, and can be so arranged that it acts during assembly as a false clutch release bearing. It is preferably slotted for cooperation with the actuating tool.

Preferably, the support member of the jig is in the form of a cradle having a contact surface against which the friction pads of the friction wheel are engaged.

Preferred embodiments of the invention will now be described, by way of example only and with reference to the accompanying drawings, in which:- 6 Figure 1 is an exploded perspective view of a conventional motor vehicle clutch of the "push to disengage" type, already described above; Figure 2 is an exploded perspective view of a friction wheel of the clutch, associated with the conventional clutch mechanism of the "pull to disengage" type which, again, has already been described; Figure 3, also referred to above, is a view in axial cross section of a conventional clutch of the Opull to disengage,, type; Figure 4 is a diagrammatic view showing a press tool and an associated locking or support tool for use in the method of manipulating the sub- assembly, in a jig in accordance with the invention; Figure 5 is a diagrammatic view in axial cros.s section, showing one stage in the method according to the invention, in which the sub-assembly consisting of the friction wheel and the clutch mechanism is manipulated in the apparatus comprising a jig in accordance with the invention; Figure 6 is a view in cross section, on a larger scale, of the central part of the jig in accordance with the invention; Figure 7 is a view in cross section showing part of a conventional clutch release unit comprising a clutch release bearing fitted on to a coupling member of a clutch of the "pull to release" type; Figure 8 is a view similar to Figure 6, showing a second embodiment of the jig in use; and i 7 Figure 9 is a view similar to Figure 3 but with the friction wheel omitted, and illustrates a modification to the method of the invention.

In the embodiment shown in Figures 4 to 6, the sub-assembly consisting of the clutch mechanism 30 and the friction wheel 2 of the clutch comprises the mechanism 30 of the "Pull to release" type already partly described with reference to Figure 3. This mechanism 30 comprises an assembly of annular members, namely the cover member 31, the diaphragm 32, the pressure plate 33, and a coupling member 41.

The cover member 31 is in the form of a hollow dish, and in this example its radial fastening flange 39 is discontinuous, so as to comprise a plurality of elements. The flange 39 has openings 9 through which fastening screws 7 (which can be seen in Figure 1) pass in order to secure the cover member 31 to the reaction plate 1.

The flange 39 extends around the outer periphery of the cover member 31, and is joined to the base portion of the cover member, which is open in the centre, through a skirt portion which is orientated generally axially, a radius 37 being formed in the zone in which the axial skirt portion joins the base portion of the cover member. This base portion has an integral, annular, seating ring 36, which in this example is discontinuous and is formed by a pressing operation on the base portion of the cover member close to the radius 37. In a modification, this seating ring may be in the form of a separate ring carried by the base portion.

The diaphragm 32 bears at its outer periphery on the seating ring 36, and, radially inwardly of this, on an annular fulcrum 35 formed on the pressure plate 33. In 8 this example, the annular fulcrum 35 is also discontinuous, and is in the form of projecting pips. By engagement against the seating ring 36 and fulcrum 35, the diaphragm 32 biasses the pressure plate 33 towards the reaction plate 1, so that the plates 1 and 33 grip between them friction pads 23 carried by the friction wheel, so that the clutch can transmit torque.

The pressure plate 33 is mounted for axial movement with respect to the cover member 31, and in this example it is mounted inside the latter. The pressure plate 33 is coupled in rotation to the cover member 31, here by means of a plurality of tangential tongues 34, each of which is fixed at one of its ends to the cover plate 31 by means of fastening lugs (see Figure 2), while at its other end each tongue 34 is secured to a radial tab or ear of the pressure plate 33.

The diaphragm 32 comprises a peripheral portion in the form of a Belleville ring, which bears externally on the seating ring 36 and internally on the fulcrum 35. This Belleville ring is extended in a central, discontinuous, portion consisting of a number of radial fingers. separated by gaps, which are enlarged in the region of the Belleville ring portion so as to define apertures. The friction wheel 2 (Figure 3) includes a support element 22 on which the friction pads 23 are fastened. The support element 22 is coupled to a hub 21 having a splined internal bore 28. In this example, the friction pads 23 are arranged on either side of the support element 22, to which they are fastened by riveting, and the support element 22 is resiliently coupled to the hub 21. More precisely, the support element 22 is fixed by means of spacing bars 26 to guide rings 25 which extend axially on either side of a damper plate 27, 9 through which the spacing bars 26 extend with a clearance around them.

Helical springs 24 are mounted in windows which are formed facing each other in the damper plate 27 and in the guide rings 25. The damper plate 27 is rotatable with the hub 21, after a circumferential clearance has been taken up in this example. To this end, the damper plate 27 has a set of teeth which are engaged, with a circumferential clearance, in complementary teeth of the hub 21, with springs of low stiffness interposed. It will be understood that the damper plate 27 may be rigidly fastened to the hub 21, for example by deformation, or in another modification, the support element 22 may be secured directly to the hub 21, for example by riveting.

Figure 7 shows the connection between the clutch release bearing 40 and the coupling member 41. The coupling member 41 is in the form of a curved collar, for cooperation with the inner ends of the fingers of the diaphragm 32. This collar is extended in an axial locating element which passes through the fingers of the diaphragm 32 via the central opening of the latter. The coupling member 41 carries a coupling ring 42 which is resiliently deformable in the radial direction, and which has radial tabs (not shown) for centring it with respect to the coupling member 41, the coupling ring 42 being retained in a cage. This cage is defined by a radial flange which is directed towards the axis of the assembly and which is formed on the locating element of the coupling member 41 at its free end, and by a retaining member 43. In this example, the latter is secured on the collar of the coupling member 41 by deformation, namely by means of tabs 44 of the member 43 which are bent over into complementary slots formed in the collar.

The coupling member 41, carrying the retaining member 43, is joined to the diaphragm 32 through a corrugated ring 45 which lies on the other side of the diaphragm 32 from the collar of the coupling member 41. This corrugated ring 45 is in contact, through its corrugations, with the diaphragm 32, and has a plurality of lugs 46 which pass through complementary apertures formed in the coupling member 41 and the retaining member 43. The lugs 46 have hooked portions on their ends, such that the ring 45 is hooked on to the coupling member 41 and retaining member 43. It will of course be understood that alternative types of fastening are possible, for example by the use of a Belleville ring bearing on the locating element of the coupling member 41, as is shown in Figure 9.

The clutch release bearing 40 comprises a manoeuvring element 48 having a sleeve for sliding on a declutching horn, together with a radial ring portion which is fixed to this sleeve. The bearing 40 also includes an actuating element, which is here in the form of a ball bearing 49 carried by the radial ring portion of the manoeuvring element 48, in which it is press-fitted.

It will be understood that the coupling member 41 is prefitted on to the diaphragm 32, using the ring 45, so that the declutching means of the clutch consist of this subassembly. In addition, the clutch release bearing is secured by snap-fitting, for which purpose the inner ring of the ball bearing 49 is extended so as to define a groove for receiving the coupling ring 42. The clutch release bearing 40 is fitted after the clutch mechanism 30 has been fitted to the reaction plate 1, and before the gearbox is offered up to the engine of the vehicle.

11 An apparatus comprising a jig is provided for manipulating the subassembly consisting of the friction wheel 2 and the clutch mechanism 30, and in particular for the purpose of actuating the declutching assembly consisting of the diaphragm 32, the clutch release bearing and the other components shown in Figure 7, in order that this declutching assembly can assume a declutching or "clutch disengaged" configuration. This configuration is seen in the upper part of Figure 3, with the clutch being shown in the lower part of that Figure in the locked up or "clutch engaged" configuration. Transition from one of these configurations to the other is achieved by exerting a tractive force in the direction of the arrow F in Figure 3.

The jig is Shown in Figures 4 to 6. It comprises essentially a support 55 and a centring member in the form of a mandrel 80. The support 55 is designed to receive, in succession, the friction wheel 2 and the clutch mechanism 30, and has an abutment surface 55 against which the fastening flange 39 of the cover member 31 of the mechanism 30 then lies. The main purpose of the mandrel 80 is to hold the friction wheel 2 centrally in the jig. The mandrel is arranged to cooperate with a locking or support tool 70, and has a first portion 81 engaged in the bore 28 of the hub 21 of the friction wheel 2. The mandrel 80 also acts as a declutching member, and has a second portion 82 for acting on the declutching assembly mentioned above and comprising the diaphragm 32 and coupling member 41.

The support 55 acts as a cradle, with the friction pads 23 interposed between a contact surface 57 of the cradle 55 and the pressure plate 33 (Figure 5). In greater detail, this contact surface 57 is offset both axially and radially from the abutment surface 58, so as to accommodate and engage the friction pads 23 of the friction wheel 2. The 12 cradle 55 also has a central portion 56 which is joined to the contact surface 57. The central portion 56 has a central nose which protrudes in line with the hub 21 of the friction wheel 2. The cradle extends generally transversely, with the generally transverse abutment surface 58 at its outer periphery and lying in a plane parallel to that of the contact surface 57. The abutment surface 58 is delimited at its outer periphery by a shoulder 59 for centring the cover member 31 of the clutch mechanism 30.

In a preferred arrangement, the cradle 55 is a single component made by hot forging, and is common to a plurality of sub-assemblies, each comprising a friction wheel 2 and a clutch mechanism 30.

Referring in particular to Figure 5, there exists in practice, between the outer periphery of the fastening flange 39 of the cover member 31 and the shoulder 59, a radial clearance J. The axial offset between the contact surface 57 and the abutment surface 58 is a function of the thickness of the friction liners 23 and of the position assumed by the pressure plate 33 when the diaphragm 32 is in its warehousing or storage configuration seen in Figure 5. A slight axial allowance is preferably provided between the pressure plate 33 and the contact surface 57, such as to ensure that the cover member 31 is in contact with the abutment surface 58. In the storage configuration, the coupling member 41 lies closer to the friction wheel 2 than when the mechanism is mounted on the reaction plate 1 of the clutch (compare Figure 5 with the lower half of Figure 3), because of the ability of the diaphragm 32 to deform. It will be realised that the contact surface 57 thus enables the length of the mandrel 80 to be reduced, and that the friction wheel 2 may be pre- centred by the 13 shoulder which joins the contact surface 57 to the abutment surface 58.

The centring and clutch disengaging mandrel 80 is annular in shape, and its first portion 81 is externally splined for cooperation with the splined internal bore 28 of the hub 21. It will be seen that this first portion 81 acts as a kind of false guide spindle. The second portion 82 of the mandrel acts as a false clutch release bearing, and is divided into a plurality of tongues, separated by slots 88 (see Figure 6) which also extend partly into the first portion 81 of the mandrel. Each of these slots 88 terminates in an open end at the free end of the second portion 82, and terminates at its other end in a blind orifice disposed in the first portion 81, close to the root of the latter. A groove 86, for receiving the coupling ring 42, is formed in the outer periphery of the second mandrel portion 82. The free end of the latter is formed with a collar which defines a shoulder 85.

The mandrel 80 is preferably made of a semi-rigid plastics material. As will be seen from the foregoing it acts to centre the coupling member 41 with the friction wheel 2. The mandrel 80 is hollow in the middle, and its second portion 82 has a frusto conical internal engagement portion 83 at its free end, which is extended in a cylindrical guide surface. The latter is itself extended radially by a groove, one of the flanks, 84, of which constitutes a shoulder on which an actuating or control tool 60 (which will be described below) acts.

The jig described above simplifies storage of the assembly, and a number of friction wheels and clutch mechanisms can be stored in a single case or container or the like, with a common cradle 55. The description that follows will make

14 it easy to understand how automatic assembly is carried out.

The sub-assembly consisting of the clutch mechanism 30 and the friction wheel 2 mounted in the support 55 and centred by the mandrel 80 of the jig, is gripped in the jig by means of a press tool 50, which is applied on the cover member 31 so as to urge the fastening flange 39 of the latter into contact with the abutment surface 58 of the cradle 55. Using the actuating tool 60, a force is exerted on either the centring mandrel 80 or the declutching assembly comprising the diaphragm 32 and coupling member 41 (also referred to here as the "declutching means"), so as to manoeuvre the declutching means in such a way as to move it from its storage configuration to its delcutching configuration.

In the embodiment seen in Figures 5 to 8, the mandrel 80 is actuated so as to manoeuvre the declutching means, while in Figure 9, it is the clutch release bearing 140 of the declutching means which is actuated. The mandrel, indicated in Figure 9 at 280, then constitutes only a centring means. In every case, centring and retention of the friction wheel 2 in contact with the pressure plate 33 is achieved by the use of the mandrel and the locking tool 70, after the declutching means of the clutch has been displaced and put into its declutching configuration.

In one mode of operation, the locking tool 70 is expandable. Thus, and with reference to Figures 4 to 7, in a subsequent step in the process, with the declutching means in is declutching configuration, the locking tool 70 acts on the first portion 81 of the declutching mandrel 80, so as to engage the friction wheel 2 with the pressure plate 33 of the clutch mechanism 30, and then to displace the sub-assembly into its declutched position, so that the latter can then be mounted on the reaction plate of the clutch. As will be understood from the foregoing, during this operation the assembly leaves the cradle 55, and the locking tool 70 immobilises the friction wheel 2 in centred contact with the pressure plate 33.

More precisely, the press tool 50 is mounted in a floating state, and has a frusto conical portion 52 for contact with the cover member 31 of the clutch mechanism 30. In a later stage of the process, the press tool 50 is caused to float in order to engage the fastening flange 39 of the cover member on the centring pins 8 (Figure 1) which are conventionally provided on the reaction plate of a clutch. This movement is represented in the lower part of Figure 5, and is made possible due to the fact that the mandrel 80 centres the coupling member 41 with respect to the friction wheel 2. In this connection, with a radial clearance existing between the inner end of the fingers of the diaphragm 32 and the locating element of the coupling member 41, it thus becomes possible to displace the diaphragm and the cover member with respect to the coupling member 41.

The press tool 50 is part of the working head of a robot (not shown) for the automatic fitting of the sub-assembly 2, 30 on the reaction plate 1. To this end, the tool 50 is provided with holes 51 through which can pass tools for securing fasteners 7 (Figure 1) for securing the cover member 31 to the reaction plate 1. In this example, these holes 51 provide passages for screwdriver heads for securing fastening studs through holes 9, Figure 3, the axis of symmetry, or pitch circle, of which is indicated by the reference numeral 100 in Figure 5. The fastening flange 39 also has calibrated apertures (the axis of 16 symmetry or pitch circle of which can be seen in the lower part of Figure 5), through which the pins 8 previously mentioned pass; while the press tool 50 has passages (not shown) through which retractable drifts can be passed for cooperation with these calibrated passages so as to obtain initial pre-centring of the cover member 31. In Figures 4 and 5, the movement of the tool 50 is represented by the arrows 91 and 92, the tool 50 being displaced axially in the direction of the arrow 93 as it moves from its Figure 4 position to its Figure 5 position.

It will be noted that the frusto conical portion 52 of the press tool enables the cover member 31 to be centred, and that this portion 52 cooperates with the radius 37 of the cover member 31. The tool 51 thus makes contact with the outer surface of the cover member 31 (i.e. the surface facing away from the pressure plate 33), and the flange 39 bears against the abutment surface 58, in locations at which an ample reaction force is available.

The actuating tool 60 is movable axially, and has a shoulder 61 at its free end, which is adapted to engage in the groove of the second portion 82 of the mandrel for contact with the shoulder 84. The shoulder 61 is formed in a collar, the size of which is adapted to that of the frusto conical portion 83 of the mandrel. This collar enables the mandrel end portion 82 to expand outwardly due to the slots 88, until the collar comes into engagement with the shoulder 84, whereupon the portion 82 relaxes once more into its normal state as seen in Figure 6. Subsequently therefore, in order to disengage the clutch, a tractive force is exerted on the mandrel 80 in the direction of the arrow 94 in Figure 4. During this operation, the second mandrel portion 82 being in engagement with the coupling ring 42 via its groove 86, the 1 17 coupling member 41, and thus the diaphragm 32 which pivots about its seating ring 36, are both moved. It will be noted that this is made possible due to the frusto conical portion 52 of the press tool 50 holding the fastening flange 39 against the abutment surface 58.

Of course, before the frusto conical portion 52 makes contact with the radius 37 of the cover member 31, the latter is initially centred by means of the drifts, mentioned above, cooperating with the calibrated holes, the cover member 31 then being preferably in engagement against the cradle 55. In a modification not shown, the tool 50 may be so shaped as to come intoengagement with the recesses in the back of the cover member 31 that define the rear of the seating ring 36.

The actuating tool 60 surrounds the locking tool 70. The latter is expandable radially, and comprises a plurality of axial spring fingers 71 for this purpose, together with a mandrel 72, of varying thickness, for expanding the spring fingers 71 radially. The expansion mandrel 72 is annular in shape and has a pointed end, joined through a frusto conical portion to the main part of the tool 70. This main part extends into the interior of the spring fingers 71, with the point of the mandrel 72 projecting axially beyond the latter. Thus, after the declutching means 32, 41 has been disengaged using the actuating tool 60, the first portion 81 of the centring mandrel 80 being displaced along the bore 28 of the hub during that operation, the spring fingers 71 are then expanded by displacing the expansion mandrel 72 towards the cover member 31 in the direction of the arrow 94 in Figure 4. Previously, the locking tool 70 has been introduced into the interior of the first portion 81 of the centring mandrel 80.

18 The locking tool 70 is part of the head of the robot mentioned above, as is the press tool SO. It is accordingly possible to displace the subassembly consisting of the clutch mechanism 30 and friction wheel 2, so as to present it at the level of the friction wheel 2 in order to proceed with the fitting of the threaded fasteners. It will be noted that the diaphragm 32 is unable to relax, because the friction wheel 22 cannot be displaced axially due to the hub 21 being blocked by the locking tool 70, this in turn being due to the expansion of the spring fingers 71 causing the first mandrel portion 81 to be expanded radially.

Thus the locking tool 70 engages the friction wheel 2 on the pressure plate 33, and locks these two components together by virtue of the radial expansion of the centring mandrel 80. It will be noted that the locking tool 70 centres the mandrel 80 itself, and therefore also centres the friction wheel 2 with respect to the cover member 31 and pressure plate 33, before the friction wheel 2 is locked in contact with the pressure plate 33.

Therefore, the fastening flange 39 having been introduced by means of the floating tool 50 on to the locating pins 8, all that is then necessary is to introduce and fasten the studs 7. Once this threaded fastening has been effected, the expansion mandrel 72 is then displaced in the opposite direction in order to allow the spring fingers 71 to relax. Finally, using a suitable extraction tool (not shown) acting on the shoulder 85, the mandrel 80 is withdrawn from the hub 21 and coupling member 41. This extraction is carried out by unclipping the coupling ring 42, that is to say the mandrel 80 is first displaced towards the friction wheel 2 so that the coupling ring 42 then comes into 19 engagement on the retaining member 43, after which displacement in the opposite direction can take place.

After the clutch mechanism 30 has been secured in the manner described above, the gearbox is offered up to the engine, whereupon the clutch release bearing can be snapfitted into the coupling member 41.

The present invention is of course not limited to the particular embodiment described above. In particular, the clutch may be of the "push to disengage" type, for example as seen in Figure 8. Accordingly, and with reference now to Figure 8, the centring and declutching member or mandrel 180 has a generally radial shoulder 1821 joined to a generally axial surface 183. The shoulder 1821 and the surface 183 are formed on the second portion 182 of the mandrel 180, the shoulder 1821 being arranged to cooperate with the inner end of the fingers of the diaphragm 132 of the clutch release mechanism. In this case, the actuating tool 60 is always engaged in the groove, and it bears on the flank of the latter that is opposed to the flank 84 in such a way that it causes the diaphragm 132 to pivot in response to an axial thrust.

After the clutch has been manipulated and the first portion 81 of the mandrel 180 has slid along the bore of the hub 21, the friction wheel 2 is adjusted by means of the locking or support tool 70 into centred contact with the pressure plate 33.

It will be noted that in the case of a clutch of the "push to release" type, the actuating tool 60 is displaced axially in the opposite direction from the tool 70 when the latter is expanded so as to immobilise the hub 21.

It will be recalled that in a clutch of the "push to release" type, the diaphragm is mounted so as to tilt between a primary point of engagement carried by the clutch cover member, and a secondary point of engagement which is also fixed with respect to the cover member through connecting means, for example spacer bars or lugs passing axially through the diaphragm and having a free end which is bent back radially away from the axis of the assembly, so as to hold a crown ring in contact with the diaphragm.

In Figure 8, tongues 181 are provided to prevent the mandrel 180 accidentally escaping from the diaphragm 132 before the assembly has been gripped together. It will also be noted that the centring mandrel 180 of Figure 8 again has the groove 86, this being universal and equally applicable to use of the jig with a clutch of either the "pull" or "push" type.

Referring now to Figure 9, this shows a modification in which, as already indicated, the mandrel, 280, has only a centring function. In this case, the head of the robot includes an actuating tool which is arranged to act on the collar 144 of a cap 141 of the clutch release bearing 140. This support for the coupling member 41 and coupling ring 42 includes, in the conventional way, a manoeuvring element 48 of U-shaped cross section, having at its outer periphery an axial flange with resiliently deformable hooked lugs 142, each of which cooperates with the edge of an opening 143 formed in the cap 141.

In the Figure 9 arrangement, the actuating tool acts in traction on the clutch release bearing 140 as indicated by the arrows. In this case, the mandrel 280 extends through the sleeve of the manoeuvring element 48, so as to come into engagement with the splined internal bore 28 of the 21 hub 21 of the friction wheel 2. It is only after the clutch release bearing 140 of the declutching mechanism of the clutch has been manipulated that centring takes place. This centring is obtained by means of the expansion mandrel 72 of the same locking tool as has been described above with reference to Figure 4.

It will be noted that in Figure 9, the mandrel 280 is centred by the internal bore of the sleeve of the manoeuvring element 48. This is however not necessarily so. As in the preceding Figures, the mandrel 280 has a collar defining a shoulder 85. In all the embodiments described above, this mandrel has a second portion (82 or 182) which extends through the declutching means of the clutch.

The clutch mechanism may of course, instead of a diaphragm, be equipped with declutching levers and coil springs. The extraction tool may extend through the declutching means of the clutch in order to be able to grip the mandrel, for example by means of a groove formed in the latter. The cradle 55 may, instead of having the central portion 56 (Figure 5), consist of a simple support element, hollow in the centre. In all cases, however, this support element is offset to accommodate the projecting mandrel 80, 180 or 280.

Finally the spring fingers 71 may be made as part of the centring member or mandrel 80, 180 or 280. In that case, this mandrel has resiliently deformable lugs level with the free end of its first portion 81, i.e. projecting beyond the hub 21. These lugs are formed with hooks such that, after the clutch has been manipulated, the lugs are caused to expand by means of the expansion mandrel 72. The latter, cooperating with the centring mandrel 80, 180 or 22 280, thus effects centring of the friction wheel 2, and then locks the latter into contact with the pressure plate 33, with the hooks of the resilient lugs immobilising the friction wheel and being locked in this position by means of the expansion mandrel 72.

23

Claims (20)

1. A jig for use during manufacture of a motor vehicle to manipulate a sub-assembly comprising a clutch friction wheel and a clutch mechanism, the friction wheel having friction liners and a hub defining an internal bore, and the clutch mechanism being a unit comprising a cover member having a fastening flange, a declutching means engaging on the cover member, and a pressure plate coupled to the cover member for rotation therewith but being movable axially with respect thereto, wherein the jig comprises a support member adapted for the friction wheel and clutch mechanism to be successively inserted therein, together with a centring member or mandrel for centring the friction wheel in the said support member, the said support member having an abutment surface for engagement of the fastening flange of the cover member therewith, and the centring mandrel being adapted to cooperate with a locking tool and comprising a first portion for engagement in the bore of the said hub.

2. A jig according to Claim 1, wherein the support member is in the form of a cradle which has a contact surface offset axially and radially from the said abutment surface, for contact with the friction pads of the friction wheel.

3. A jig according to Claim 2, wherein the cradle has a central portion joined to the said contact surface and having a protruding nose located so as to be aligned with the hub of a friction wheel located in the cradle.

4. A jig according to any one of the preceding Claims, wherein the abutment surface is delimited at its outer periphery by a shoulder for precentring the cover member of the clutch mechanism.

24

5. A jig according to any one of the preceding Claims, wherein the said first portion of the centring mandrel is splined for cooperation with corresponding splines in the bore of the hub.

6. A jig according to any one of the preceding Claims, wherein the centring mandrel further includes a second portion for acting on the declutching means of the clutch, whereby the centring mandrel also acts as a declutching means.

7. A jig according to Claim 6, wherein the said second portion of the centring mandrel is interrupted by a plurality of slots extending partly into the said first portion of the mandrel.

8. A jig according to Claim 7 wherein, the declutching mechanism of the clutch including a coupling member carrying a coupling ring, the said second portion of the centring mandrel has a groove for receiving the said coupling ring.

9. A jig according to Claim 8, wherein the free end of the said second portion of the centring mandrel has a shoulder for engagement of an extraction tool thereon.

10. A jig according to Claim 7 or Claim 8, wherein the said second portion of the centring mandrel has a shoulder for action of an actuating tool thereon.

11. A method of manipulating a sub-assembly comprising a clutch friction wheel and clutch mechanism, using a jig according to any one of the preceding Claims, wherein a press tool is engaged on the cover member of the clutch mechanism so as to press the fastening flange of the cover member into contact with the abutment surface of the i i i support member of the jig, and wherein an actuating tool is applied on either the centring mandrel or the declutching means of the clutch, whereby to manoeuvre the declutching means so as to shift it from its storage configuration to its declutching configuration.

12. A method according to Claim 11 wherein, the declutching means of the clutch being in its declutching configuration, a locking tool is engaged on the said first portion of the centring mandrel, so as to apply the friction wheel to the pressure plate of the declutching mechanism and then to displace the sub-assembly for fitting of the latter on the reaction plate of the clutch.

13. A method according to Claim 12 wherein, the said press tool being floatingly mounted and having a frusto-conical portion for contact with the cover member of the clutch mechanism, the press tool is caused to float whereby to engage the fastening flange of the cover member on to centring pins of a reaction plate of the clutch.

14. A method according to Claim 13, wherein, the press tool having apertures for passage of fastening tools therethrough, the said fastening tools are passed through the said apertures so as to secure fasteners whereby to fasten the cover member of the clutch to its reaction plate.

15. A method according to any one of Claims 11 to 14 wherein, the locking tool being an expandable gripping tool comprising a plurality of spring fingers and a central expanding mandrel for expanding the spring fingers, the expanding mandrel is operated so as to expand the spring fingers, whereby to cause the friction wheel of the clutch to be held to the clutch mechanism.

26

16. A method according to any one of Claims 11 to 15, wherein the centring mandrel is extracted after the clutch mechanism has been fastened to the reaction plate.

17. A jig for use during manufacture of a motor vehicle in manipulating a sub-assembly comprising a clutch friction wheel and a clutch mechanism, constructed, arranged and adapted to operate substantially as described in the foregoing description with reference to Figures 4 to 6 of the accompanying drawings.

18. A jig according to Claim 17, modified substantially as described in the foregoing description with reference to Figure 8 of the accompanying drawings.

19. A jig according to Claim 17, modified substantially as described in the foregoing description with reference to Figure 9 of the accompanying drawings.

20. A method of manipulating a sub-assembly comprising a clutch friction wheel and a clutch mechanism using a jig according to any one of Claims 17 to 19, the method being substantially as described in the foregoing description.