GB2338767A

GB2338767A - Clutch release bearing retainer arrangement.

Info

Publication number: GB2338767A
Application number: GB9906391A
Authority: GB
Inventors: Frederic Ponson; Benoit Arnault; Herve Girardin
Original assignee: SKF France SAS
Current assignee: SKF France SAS
Priority date: 1998-03-25
Filing date: 1999-03-20
Publication date: 1999-12-29
Anticipated expiration: 2019-03-20
Also published as: FR2776727B1; DE19913167A1; GB2338767B; FR2776727A1; GB9906391D0

Abstract

The arrangement comprises a guide tube 2 having a tubular 24 and a radial attachment 25 parts, a release bearing 1 having an operating element 5 mounted slidably on the tubular part, and a release fork 3 for acting on the release bearing. To facilitate assembly of the clutch, the operating element is aligned and temporarily retained on the guide tube by retaining means which may comprise a helical spring 29 mounted (press-fitted Fig. 6) on a bearing surface 27, one end 31 of which spring engages the operating element and the other being retrained by a tab 28 on the radial part. Alternatively the retaining means may comprise a conical helical spring attached to the tubular part (Fig. 7) or tagged 51 and tabbed 52 washers (Figs. 10, 13). The fork is clipped to the operating element which is released from restraint by operating the fork.

Description

C is 2338767 Device for controlling a clutch

The present invention relates to the field of clutch control units, particularly for motor vehicles.

Such clutch control units generally comprise a guide tube attached to the gearbox housing, a clutchrelease bearing mounted so that it can slide along the guide tube and capable of acting on the clutch-release device of the clutch, and a clutch-release fork subject to the action of control means and capable of acting on the clutch-release bearing.

The clutch-release fork comprises a housing so that it can be mounted to pivot on at least one stationary support point, for example integral with the clutch housing. The guide tube has an attachment end and a free end.

A device for controlling a clutch designed to form a unit assembly prior to mounting is known from French Document 2,662,769 (VALEO). The guide tube bears a retractable stop for preventing the clutch-release bearing from becoming detached from the guide tube as it slides axially towards its free end. The fork is circumferentially immobilized relative to the guide tube.

Such a device has the drawback of requiring a relatively high number of parts and, in particular, needs there to be an additional retractable stop for securing the thrust bearing and guide tube together.

Document FR-A-2,746,468 (Fichtel & Sachs) relates to a clutch-release device comprising a clutchrelease mounting element, a guiding tube passing axially through the mounting element, and on which the latter is radially guided so that it is axially mobile, and a clutch lever articulated to a bell housing. The mounting element, the guiding tube and the clutch lever are kept assembled as a structural unit prior to their being mounted, by members which limit movement. The is - 2 guiding tube is equipped at one end with a radial flange and at the opposite end with an outwardly facing tooth. The mounting element may be equipped with engagement teeth projecting radially outwards and passing through a hole in the clutch lever. However, such a device permanently limits movement, which makes a dismantling operation, for example for changing a part, extremely difficult.

The object of the present invention is to overcome the drawbacks of the aforementioned devices by proposing a device for controlling a clutch in which the thrust bearing, the guide tube and the clutchrelease fork temporarily, before mounting, form a unit assembly which remains easy to dismantle subsequently.

The device for controlling a clutch according to the invention is of the type comprising a guide tube equipped with a tubular part and with a radial part for attaching to a gearbox housing, a clutch-release bearing equipped with an operating element and mounted so that it can slide along the tubular part of the guide tube, a clutch- release fork capable of acting on the clutch-release bearing and having a portion arranged axially between the clutch-release bearing and the attachment part of the guide tube. The device for controlling a clutch comprises a member for temporarily axially connecting the guide tube and the clutchrelease bearing. The member for temporary axial connection is mounted on the guide tube axially between the operating element and the attachment part of the guide tube, so as to keep the guide tube and the clutch-release bearing together. The fork may be connected to the thrust bearing.

The clutch-release fork may be coupled axially and radially to the clutchrelease bearing and connected angularly to the said bearing in a plane perpendicular to the axis of the bearing.

In one embodiment of the invention, the connecting member comprises means of attachment to the guide tube.

Advantageously, the connecting member comprises means of axially retaining the thrust bearing. The operating element may comprise retaining surfaces intended to cooperate with the axial-retention means of the connecting member. These retaining surfaces may be formed by an axial extension of the operating element towards the attachment part of the guide tube.

In one embodiment of the invention, the connecting member is a helical spring. A portion of a turn of the spring may cooperate with a retaining surface of the operating element.

In another embodiment of the invention, the connecting member is an annular washer comprising flexible tabs cooperating with the operating element. The washer may comprise tags for catching on the guide tube.

The connecting member may be attached to the tubular part of the guide tube or to a cylindrical bearing surface of the guide tube, the diameter of this exceeding that of the tubular part.

The connecting member may be push-fitted onto the guide tube. Advantageously, the guide tube comprises means for ensuring a correct angular orientation of the connecting member with respect to the said guide tube.

These means which serve to orientate the connecting member angularly with respect to the guide tube may also serve to secure these two parts together axially.

The guide tube may have a tab on its attachment part for cooperating with the connecting member.

The guide tube may have an opening for cooperating with a portion of the connecting member.

This then forms a thrust bearing/fork/guide tube subassembly which can easily be transported and handled without the risk of accidental disassembly and in which the parts are and remain correctly angularly orientated with respect to one another. This subassembly is easily mounted on a gearbox housing. The fork/thrust bearing subassembly is then axially detached from the guide tube, the thrust bearing becoming free to move axially with respect to the said guide tube.

The invention will be better understood from studying the detailed description of a number of embodiments taken by way of entirely non-limiting examples and illustrated by the appended drawings, in which:

Figure 1 is a view in axial section of a device for controlling a clutch according to a first embodiment of the invention; Figure 2 is a figure similar to Figure 1, showing the device after a first use; Figure 3 is a front elevation of the device of Figure 1, the operating element and the fork not being depicted; Figure 4 is a view in axial section of a device according to Figure 1, the plane of sectioning being offset by an angle of 900; 25 Figure 5 is a rear elevation of the device of Figure 1, the guide tube not being depicted; Figure 6 is a partial view in axial section of an alternative form to Figure 1; Figures 7 and 8 are views similar to Figures 1 and 2 and show a third embodiment of the invention; Figure 9 is a rear elevation of an alternative form of Figures 7 and 8; Figures 10 and 11 are views similar to Figures 1 and 2 of a fourth embodiment of the invention; Figure 12 is a rear elevation of the device of Figure 10, the guide tube not being depicted; - 5 Figures 13 and 14 are views similar to Figures 1 and 2 of a fifth embodiment of the invention; and Figure 15 is a front elevation of the device of Figure 13 with the thrust bearing not depicted.

As illustrated in Figures 1 and 2, the device for controlling a clutch according to the invention comprises a thrust bearing 1, a guide tube 2 and a clutch-release fork 3 depicted partially in chain line.

The clutch-release bearing 1 comprises a rolling-contact bearing 4 mounted on an operating element 5 which comprises a tubular portion 6 which can slide with respect to the guide tube 2, and a radial flange 7. The rolling-contact bearing 4 comprises a thin-walled inner race 8 produced by pressing a metal sheet or tube and exhibiting a toric raceway 9 for a row of balls 10 held by a cage 11. The inner race 8 also comprises an extension facing outwards in the form of a radial flange 12 which comes into rubbing contact with the inner front surface of the radial flange 7.

The rolling-contact bearing 4 is completed by an outer race 13 which is also thin-walled and produced by pressing a sheet or a tube and which exhibits a toric raceway 14 for the balls 10, and a toric portion 15 which comes into contact with the surface of the diaphragm 16 of a clutch device, depicted in chain line, as the thrust bearing 1 assembly moves longitudinally with respect to the guide tube 2 on which the operating element 5 slides. The rollingcontact bearing 4 is protected by an end plate 17 attached to the outer race 13.

A sleeve 18 made of an elastic material, for example an elastomer or natural rubber, is arranged inside the inner race 8 and has a number of ribs 19 parallel to the axis of the thrust bearing 1, these ribs facing inwards and their internal free edge coming into contact with the external surface of the tubular portion 6 of the operating element 5 which is made of a 1 6 rigid synthetic material, for example a synthetic material containing inorganic fillers or the like.

The elastic sleeve 18 has an annular lip 20 which seals the rollingcontact bearing 4 by coming into contact with the outer race 13. An annular rib 21 arranged at the end of the tubular portion 6 retains the bearing 4 equipped with its elastic sleeve 18 on the operating element 5.

The radial flange 7 of the operating element 5 is formed by a metal ring over which the tubular portion 6 is moulded. The metal ring has preferably undergone a surface hardening treatment. The radial flange 7 acts as a contact surface for the clutch release fork 3 which exerts a force in the axial direction to cause the thrust bearing 1 to move in its entirety during a clutch-release operation.

The tubular portion 6 of the operating element 5 is extended on the opposite side of the radial flange 7 to the bearing 4 and is equipped with two diametrically opposed housings 22 opening onto the cylindrical outer surface of the tubular portion 6 and bounded axially on one side by the radial flange 7 and on the other side by a rim 23 of the tubular portion 6. By way of an alternative, it is possible to provide an operating element 5 which is equipped with just one housing 22, or, on the other hand, a number of housings 22 areater than two.

The guide tube 2 comprises a tubular part 24 on which the thrust bearing 1 slides, and a radial attachment part 25 extending the end of the tubular part 24 which is on the opposite side to the clutch diaphragm 16 outwards. Between the tubular part 24 and the attachment part 25 there is a shoulder 26 which has a cylindrical bearing surface 27 whose diameter exceeds -that cf the tubular part 24 and which is adjacent to the latter. A tab 28 is formed in the attachment part 25, for example by partial cutting, and extends slightly towards the thrust bearing 1.

A connecting spring 29 with helical turns is arranged on and around the cylindrical bearing surface 27 and comprises an end of turn 30 which is slipped behind the tab 28. The connecting spring 29 and the guide tube 2 are thus secured together with a predetermined angular orientation of these two parts with respect to each other. The turn end 31 opposite the turn end 30 extends radially inwards along the shoulder 26 and is arranged in the housing 22 of the operating element 5. The connecting spring 29 is connected to the thrust bearing 1 axially and in terms of rotation, as can be seen in Figure 1. This then yields a preassembled thrust bearing/guide tube subassembly, the elements of which are correctly angularly orientated with respect to each other, it being possible for the said subassembly to be handled and transported with ease.

In Figures 4 and 5 it can be seen that the fork 3 comprises a surface 32 for contact with the corresponding surface 33 of the radial flange 7, the opposite surface 34 of which rests against the bearing 4. The opposite surface 35 of the fork 3 faces the connecting spring 29. In Figure 5, the spring 29 has been depicted in chain line to make for easier understanding and show how the turn end 31 is positioned in the housing 22. Nevertheless, the spring 29 is permanently secured to the guide tube which has not been depicted. The connection between the spring and the operating element 5 is only temporary. The thrust bearing 1 and the guide tube 2 are thus temporarily secured together, the turn end 31 being able to disengage from the housing 22 by virtue of its elasticity when the thrust bearing 1 is moved away from the attachment part 25.

The tubular part 6 of the operating element 5 comprises, on the opposite side of the radial flange 7 to the clutch diaphragm, an external surface 36 receiving two clips 37 which, on the one hand, allow 8 the said external surface 36 to be protected from contact with the fingers 38 of the fork 3 and, on the other hand, axially couple the thrust bearing 1 to the fork 3 while at the same time preventing the operating element 5 from rotating on the guide tube which has not been depicted.

Each clip 37 comprises a flat part 39 perpendicular to the radial flange 7 and partially surrounding the external surface 36 of the tubular portion 6. At both its free ends, the flat part 39 is extended by a bend 40 extending radially outwards and thus forming a boss capable of cooperating with a protrusion 41 formed on the internal edge of the finger 38 to radially retain the thrust bearing 1 with respect to the fork 3. Beyond each bend 40, the clip 37 is extended by a tab 42 which serves to catch it on the external surface 36. Extending from the axially opposite edge of the flat part 39 to the radial flange 7 is a rim 43 which faces radially outwards so as to form a means of axial retention acting on the surface of a finger 38 with respect to the clutch-release bearing 1 on the opposite side to the said radial flange 7.

The free end of the tubular portion 6 adjacent to the clips 37 is equipped, in the region of the tabs 42, with outgrowths 44 facing radially outwards and extending beyond the tabs 42 which are thus held axially between the outgrowths 44 and the radial flange 7, which constitutes a means of axially retaining the clips 37 with respect to the clutchrelease bearing 1.

The radial outgrowths 44 give the end of the axial portion 6 a roughly rectangular shape.

The external diametrically opposed surfaces 45 intended to part 39 of the clips 3 cooperation with internal 38 of the fork 3, allow and mutually surface 36 comprises two parallel flat be in contact with the flat 7. These flat parts 39, in edges of the contact fingers the thrust bearing 1 to be guided but prevented from angular movement with respect to the control fork 3, thus avoiding any risk of the guide sleeve 5 rotating on the guide tube.

Between these two flat surfaces 45, the exterior surface 36 has a profile that is symmetric with respect to the axis of the clutch-release bearing 1. A protrusion 46 extends radially outwards in a direction perpendicular to that of the rims 43 of the clips 37 and is arranged near to the flat surfaces 45 so as to be able to cooperate with a tab 42. Thus, a clip 37 is arranged with its flat part 39 in contact with the flat surface 45, and each tab 42 is in contact with a protrusion 46 on each side of the flat surface 45. Each tab 42 is slightly bent beyond the protrusion 46 so that it exhibits an end 47 which is closed in relative to the protrusion 46. The two protrusions 46 intended to cooperate with two tabs 42 of a clip 37 are further apart than the two ends 47 of the said tabs 42, which allows the clip 37 to be retained on the exterior surface 36. The clip 37 offers the radial rim 43 for axially retaining the fingers 38 relative to the clutch-release bearing 1. The clip 37 is itself axially retained by the outgrowths 44 of the end of the axial portion 6 which extend radially beyond the tabs 42.

A clip 37 may be mounted on the exterior surface 36 through a simple radial movement which brings it towards the flat surface 45. During such a movement, the end 47 of the tabs 42 comes into contact with the protrusions 46, and this causes the two tabs 42 of the clip 37 to part. Through elasticity, the ends 47 tighten again after they have passed over the outgrowths 46, and this causes the clip 37 to be retained radially relative to the operating element 5.

The exterior surface 36 also comprises the two diametrically opposed housings 22 which are angularly offset by 90' relative to the flat surfaces 45. Each housing 22 is delimited by the radial flange 7, the rim 23 and two partitions 49 which meet on the outgrowths 1 44. The turn end 31 of the connecting spring 29 projects into one of the housings 22, and this provides an axial and angular connection between the said connecting spring 29 and the thrust bearing 1. The fork 3 is secured to the thrust bearing once the clips 37 have been fitted.

This operation may be performed in two ways:

- either by introducing the fork fingers obliquely between the bends 40 and the rims 43 of the clips and then straightening the fork; - or by introducing the fork onto the thrust bearing radially. The bends 40 move aside under the pressure exerted by the internal radial protrusions 41 of the fork and then return to their initial shape, thus radially retaining the thrust bearing on the fork.

A guide tube, thrust bearing and fork assembly becomes available that is in the form of a single unit before it is mounted. The thrust bearing is axially and angularly connected to the guide tube. The fork is itself coupled to the thrust bearing axially, radially and angularly in a plane perpendicular to the axis of the thrust bearing. The assembly can be mounted without the operator having to worry about the relative angular position of these three parts with respect to each other, the assembly being preassembled and delivered with the appropriate angular orientation of the said three parts.

After the subassembly has been mounted on the gearbox housing, manoeuvring the fork 3 causes the thrust bearing 1 to move and the connecting spring 29 and the thrust bearing 1 to disconnect, the turn end 31 the housing 22 by virtue of its (Figure 2). The connecting spring 29 has no subsequent operation of the clutch. When an element of the clutch, for example the bearing 4, needs to possible tube 2.

coming out of flexibility influence on be replaced for reasons of wear, it is to proceed wIthout dismantling the guide The alternative form of Figure 6 is similar to Figure 1, except that the connecting spring 29 is pushfitted tightly via its last turns onto the cylindrical bearing surface 27. This pushfit provides the axial and circumferential connection between the connecting spring 29 and the guide tube 2. The tab 28 and the turn end 30 of Figure 1 are therefore no longer needed. This method of catching the spring on the guide tube can be reinforced, if necessary, by a spot of solder deposited between the last turn of the spring and the guide tube.

Of course, nothing would prevent the use of a spring tightly push-fitted via its last turns onto a cylindrical bearing surface and one turn end of which would engage in a catching tab as illustrated in Figures 1 to 3.

The embodiment illustrated in Figures 7 to 9 is similar to the one in Figure 1, except that the attachment part 25 of the guide tube 2 has no tab. The connecting spring 29 is of the conical helical type and is attached by its innermost turn 48 to the tubular portion 24 of the guide tube 2 close to the shoulder 26, the other turns of the connecting spring 29 extending up against the said shoulder 26. The turn end 31 of the connecting spring 29 is arranged in the housing 22 of the tubular portion 6 of the operating element 5.

In Figure 8, it movement away from the action of the fork 3, away from the shoulder the connecting spring housing 22 by slipping into position against bearing 1 is now free tube 2 for can be seen that after an axial attachment part 25, under the the thrust bearing 1 has moved 26 and that the turn end 31 of 29 has disengaged from the over the edge 23 and has come the shoulder 26. The thrust to slide axially on the guide clutch-engagement and clutch-release manoeuvres.

In these embodiments, the connecting spring 29 is fitted onto the guide tube 2 in such a way that the 1 - 12 turn end 31 forming a radial return intended to cooperate with the housing 22 of the thrust bearing 1 is correctly angularly orientated relative to the guide tube 2.

This orientation is achieved by clamping the connecting spring 29 on the guide tube 2 or by inserting an end turn of the connecting spring 29 in a catching tag of the attachment part 25 of the guide tube 2. All that is then required is for the thrust bearing 1 to be introduced onto the guide tube 2, for the turn end 31 of the connecting spring 29 to be fitted into its housing 22 and for the fork 3 to be installed on the thrust bearing 1. The housing 22 accommodating the turn end 31 of the connecting spring 29 has a substantially radial retaining surface forming an axial stop for the connecting spring 29 and, on each side of the said retaining surface, two substantially radial lateral surfaces angularly connecting the end turn 31 of the connecting spring 29 and the operating element 5.

As the thrust bearing 1 is itself angularly connected to the control fork 3, it is therefore possible to form an assembly comprising thrust bearing 1, guide tube 2 and fork 3, the components of which are correctly angularly orientated with respect to each other, which makes the said assembly easier to mount later on the gearbox housing. All that will actually remain to be done will be to correctly orientate the guide tube 2 with respect to the gearbox housing and fit the attachment screws without worrying about the mutual angular orientation of the other parts. Furthermore, the thrust bearing 1 has two lateral clips 37 fixed to the operating element 5 and comprising means allowing the said thrust bearing 1 and the control fork 3 to be connected axially and radially. An assembly that can easily be handled without risk of the parts becoming detached is thus formed.

The embodiment illustrated in Figures 10 to 12 is similar to the one in Figures 7 to 9, except that the connecting spring is replaced by a connecting washer 49 comprising a radial annular part 50 from the bore of which there extend tags 51 for catching on the exterior surface of the tubular part 24 of the guide tube 2. The catching tags 51 point obliquely towards the said tubular part 24 so as to grip the latter, allowing a relative movement in an axial direction towards the attachment part 25, but through a bracing effect preventing any relative movement in the opposite direction.

Extending from the outer edge of the annular part 50 are two substantially axial retaining tabs 52 is arranged symmetrically with respect to the axis of the washer 49 and ending in a hook which cooperates with a complementary surface of the guide sleeve 5. The stop washer 49 may be manufactured by cutting, pressing and possibly treating a mild steel or spring steel sheet.

The tubular part 6 of the operating element 5 comprises, at its free end on the same side as the attachment part 25, a rim 53 extending radially outwards and with which the retaining tabs 52 can cooperate elastically to temporarily axially retain the thrust bearing 1 with respect to the guide tube 2.

The embodiment illustrated in Figures 13 to 15 is similar to that of Figures 10 to 12, except that the stop washer 54 is arranged on the cylindrical bearing surface 27 of the shoulder 26. The stop washer 54 comprises a radial annular part 55 the bore of which is the origin of the catching tags 56 similar to the catching tags 51 of Figures 10 to 12 and two retaining tabs 57 extending axially towards the thrust bearing 1 and radially inwards so that they can cooperate with the rim 53 of the operating element 5. The stop washer 54 comprises an axial rim 58, for stiffening, extending from the outer edge of the annular part 55. As the catching tags 56 and the retaining tabs 57 start from 1 - 14 the same edge of the annular part 55, the stop washer 54 has no catching tags 56 in the places where the retaining tabs 57 start.

To correctly angularly orientate the stop washer with respect to the guide tube and therefore the thrust bearing with respect to the guide tube, the stop washer may have an axial tag 59 extending the axial rim 58 at one point and entering an opening 60 f ormed in the attachment part 25 of the guide tube.

Tt is also possible to envisage a cutout made in the axial rim and cooperating with a tag extending from the attachment part 25 of the guide tube like the tag shown in the embodiment of Figure 3.

The process of separating the parts is always the same for all of these embodiments. Once the assembly comprising thrust bearing, fork and guide tube has been mounted on the gearbox housing, all that is required is for the thrust bearing to be manoeuvred axially using the fork in the direction which moves the thrust bearing closer to the diaphragm. The connecting member - spring or stop washer - remains secured to the guide tube by virtue of the means of attachment, while the temporary means of retention - end turns of the spring, end of the tabs of the stop washer disengage from the retaining surfaces of the thrust bearing. The device is then ready to operate.

Although in the embodiments illustrated, the fork is of the type with two parallel fingers, the device according to the invention could just as well employ a fork of the type with a central slot, that is to say a fork in which the two fingers meet at their end to form a central slot, the parallel edges of which form bearing surfaces to cooperate with the operating element.

An effective temporary connection between the thrust bearing/fork subassembly and the guide tube is thus achieved in a simple and inexpensive way, using a small number of parts, the thrust bearing/fork 15 subassembly being axially detached from the guide tube in a simple and reliable way simply by manoeuvring the f ork.

1 16

Claims

1. Device for controlling a clutch of the type comprising a guide tube equipped with a tubular part and with a radial part for attaching to a gearbox housing, a clutch-release bearing equipped with an operating element and mounted so that it can slide along the tubular part of the guide tube, a clutch release fork capable of acting on the clutch-release bearing and having a portion arranged axially between the clutch-release bearing and the attachment part of the guide tube, and a member for temporarily axially connecting the guide tube and the connecting member is mounted on the guide tube axially between the operating element and the attachment part of the guide tube, so as to keep the guide tube and the clutch-release bearing together.

2. Device according to claim 1, characterised in that the clutch-release fork is coupled axially and radially to the clutch-release bearing and is connected angularly to the said bearing in a plane perpendicular to the axis of the bearing.

3. Device according to claim 1 or 2, characterised in that the connecting member comprises means of attachment to the guide tube.

4. Device according to any one of the preceding claims, characterised in that the connecting member 17 comprises thrust bearing means of axially retaining the

5. Device according to claim 4, characterised in that the operating element comprises retaining surfaces intended to co-operate with the axialretention means of the connecting member.

6. Device according to claim 5, characterised in that the retaining surfaces are formed on an axial extension of the operating element towards the attachment part of the guide tube.

7. Device according to any one of claims 4 to 6, characterised in that the connecting member is a helical spring.

8. Device according to claim 7, characterised in that a portion of a turn of the spring co-operates with a retaining surface of the operating element.

9. Device according to any one of claims 4 to 6, characterised in that the connecting member is an annular washer comprising flexible tabs cooperating with the operating element.

10. Device according to claim 9, characterised in that the annular washer comprises tags for catching on the guide tube.

1 18

11. Device according to any one of the preceding claims, characterised in that the connecting member is attached to the tubular part of the guide tube.

12. Device according to any one of the claims 1 to 10, characterised in that the connecting member is attached to a cylindrical bearing surface of the guide tube, the diameter of this exceeding that of the tubular part.

13. Device according to any one of the preceding claims, characterised in that the connecting member is push-fitted onto the guide tube.

14. Device according to any one of the claims 1 to 13, characterised in that the guide tube comprises means for ensuring a correct angular orientation of the connecting member with respect to the said guide tube.

15. Device according to claim 14, characterised in that the means which serve to orientate the connecting member angularly with respect to the guide tube also serves to secure these two parts together axially.

16. Device according to claim 14 or 15, characterised in that the guide tube has as tab on its attachment part for co-operating with the connecting member 19

17. Device according to claim 14 or is, characterised in that the guide tube has an opening for co-operating with a portion of the connecting member.

18. A device for controlling a clutch of the kind set forth substantially as described herein with reference to and as illustrated in Figures 1 to 5 of the accompanying drawings.

19. A device for controlling a clutch of the kind set forth substantially as described herein with reference to and as illustrated in Figure 6 of the accompanying drawings.

20. A device for controlling a clutch of the kind set forth substantially as described herein with reference to and as illustrated in Figures 7 to 9 of the accompanying drawings.

21. A device for controlling a clutch of the kind set forth substantially as described herein with reference to and as illustrated in Figures 10 to 12 of the accompanying drawings.

22. A device for controlling a clutch of the kind set forth substantially as described herein with reference to and as illustrated in Figures 13 to 15 of the accompanying drawings.