GB2058249A

GB2058249A - Clutch

Info

Publication number: GB2058249A
Application number: GB8027614A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-09-06
Filing date: 1980-08-26
Publication date: 1981-04-08
Also published as: DE3033053A1; JPS5697630A; AU6199880A

Abstract

A clutch for a motor vehicle includes a pressure plate (11) which has a discardable face plate (13) intended to be damaged by cutting elements (17) embedded in the lining (15) of clutch plate (10) after the lining has worn to a predetermined extent, so that the clutch is difficult to rebuild using reconditioned parts. <IMAGE>

Description

SPECIFICATION Clutch This invention relates to a clutch for a motor vehicle and a clutch plate and a pressure plate therefor.

The rebuilding and reconditioning of clutches has become a common practice over the years, wherein worn or damaged clutch linings are removed from clutch plates and replaced with new linings and pressure plate surfaces damaged by worn clutch plate linings are machined down to restore them for re-use. The clutch rebuilding industry has reached such proportions that the original manufacturer's market is effectively limited to the clutches installed in new vehicles, thereafter the market passes to the clutch rebuilders and the original manufacturer has very little or no control over the quality of reconditioned parts installed in the clutch.

It is an object of this invention to alleviate this difficulty by providing a clutch for a motor vehicle which will be difficult to rebuild so that it will be easier and more economical to replace worn parts by new parts, thereby facilitating quality control.

The applicant believes that, once the market for the replacement of worn clutch parts is recaptured by the manufacturer of new parts, methods of mass production will result in the replacement of worn parts by new quality controlled parts being cheaper than the rebuilding of the clutch using reconditioned parts.

According to the invention there is provided a clutch for a motor vehicle which includes a pressure plate comprising a support plate and a discardable face plate removably attached to the support plate and a clutch plate adjacent the face plate, the clutch plate having a lining with a cutting element embedded therein, which cutting element is adapted to protrude from the lining and damage the face plate after the lining has been worn down to a predetermined extent.

This invention also extends to a clutch plate or a pressure plate, as defined for use in a clutch according to the invention.

The invention further extends to a discardable face plate for a pressure plate, as defined.

The cutting element may consist of a conventional rivet used for securing the lining to the clutch plate.

In another embodiment of the invention, the cutting element comprises a member which has a base and a cutting edge protruding from the base, the cutting element being adapted to be received in a mating recess provided for this purpose in the lining so that the cutting edge will emerge from the lining after a predetermined amount of wear of the lining to cut into and thereby damage the face plate. The cutting element may further include a stem perpendicular to the base and directed away from the cutting edge, to act as a rivet for securing the lining to the clutch plate.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is an exploded perspective view of part of a clutch of a motor vehicle showing a pressure plate and a clutch plate according to the invention, with some details omitted for the sake of clarity; Figure 2 is a cross sectional view of a portion of a clutch lining of a clutch plate according to the invention; Figure 3 is an enlarged perspective view of one embodiment of a cutting element for a clutch plate according to the invention; and Figure 4 is a cross sectional view of a portion of a clutch plate according to the invention.

Referring to Figure 1, there is shown part of a clutch of a motor vehicle comprising a clutch plate 10 and a pressure plate 11.

The pressure plate 11 consists of two parts, a support plate 12 and a face plate 13, which are secured together by means of bolts 14. To render the assembly of the plates 12 and 1 3 more rigid, mating castellations are provided on the plates 12 and 13. Threaded holes 13.1 are provided in the plate 13 for the bolts 14 to screw into. The threads in the holes 13.1 are reasonably short but nevertheless of sufficient length to ensure that the bolts 14 can be tightened sufficiently firmly to secure the plates 12 and 13 together.

The clutch plate 10 comprises a plate 11 3 sandwiched between a pair of linings 1 5 and 111.

The lining 1 5 is provided with a plurality of recesses 1 6, only two of which are shown in Figure 1. The actual shape of each recess 1 6 can be seen more clearly in Figure 2. The recess 1 6 is adapted snugly to receive a cutting element 17, shown in Figure 3.

The cutting element 17 comprises a base 1 8 and a cutting edge 1 9 protruding substantially at right angles from the base 1 8. On the other side, the base 18 is provided with a stem 110 which, in actual fact, acts as a rivet.

The assembly of the clutch plate 10 will now be described with reference to Figure 4 of the drawings. Prior to assembly, the cutting element 17 is inserted into the recess 16 as shown. The stem 110 of the cutting element 1 7 is passed through a larger than necessary hole 1 12 in the plate 1 13. A suitably sized washer 114 of a thickness equal to that of the plate 113 is used to center the stem 110 passing through the hole 1 12. The end of the stem 110 is thereafter passed through a hole in the other lining 111 and riveted over in the usual way. An ordinary rivet 11 5 is also passed through suitable holes to secure the two linings 15 and 111 to the plate 113, as is known in the art.The head of the rivet 11 5 is located in the lining 111 and the rivet 11 5 is, therefore, riveted over in the lining 1 5 containing the cutting element 17.

In use, the lining 1 5 containing the cutting element 1 7 is adapted to contact the face plate 13 of the pressure plate 11. After a period of use, the outer face of the lining 1 5 is worn away at which stage the cutting edge 1 9 of the cutting element 1 7 appears. At this stage, the cutting edge 19 will start cutting into the surface of the face plate 1 3.

The holes in the face plate 1 3 into which the bolts 14 are screwed are located along the periphery of the face plate 13. This positioning allows the cutting edge 19 of the cutting element 17 to cut away the surface of the plate 13 on the inside of the bolts 14 without any effect on that portion of the plate 13 into which the bolts 14 are screwed.

With continued use the linings 1 5 and 111 are worn to such an extent that an overhaul of the clutch becomes necessary.

It is now impossible to machine down the entire surface of the face plate 13 since this entails also machining that area containing the holes with the threads into which the bolts 14 are screwed. As soon as this is done, the threads are destroyed and it is no longer possible to secure the face plate 13 to the support plate 12. As a result, a new face plate 13 must be used.

In order to attempt the rebuilding of the clutch plate 10, each rivet 11 5 must be drilled out in a known manner from the riveted side. Likewise it will be necessary to drill out the stem 110 of the cutting element 17. Drilling is done from the riveted side, i.e. from the lining 111. Once drilling is accomplished, the rebuilder is faced with an outsize hole 112, too large simply to insert an ordinary rivet, thereby complicating the rebuilding of the clutch plate 10.

Alternative embodiments of the invention are possible without departing from the scope of the invention. For example, the bolts 14 securing the plate 12 and the plate 1 3 together may also be passed through from the side of the plate 13 and screwed into the support plate 12. In this event, the heads of the bolts 14 will be countersunk into the surface of the plate 13. Machining down of the surface plate 13 in an effort to recondition the face plate 13 will, in this case, result in the heads of the bolts 14 being machined away with the result that they can no longer secure the plates 12 and 13 together. Alternatively, if the bolts 14 are removed prior to machining the surface, the heads of the bolts 14 will protrude from the surface of the face plate 13 once the machining operation has been completed.

Claims

1. A clutch for a motor vehicle which includes a pressure plate comprising a support plate and a discardable face plate removably attached to the support plate and a clutch plate adjacent the face plate, the clutch plate having a lining with a cutting element embedded therein, which cutting element is adapted to protrude from the lining and damage the face plate after the lining has been worn down to a predetermined extent.

2. A clutch according to claim 1 wherein the cutting element comprises a rivet securing the lining to the clutch plate.

-

3. A clutch according to claim 1 wherein the cutting element comprises a member which has a base and a cutting edge protruding from the base, the cutting element being housed in a mating recess provided for this purpose in the lining so that the cutting edge will emerge from the lining after a predetermined amount of wear of the lining to cut into and thereby damage the face plate.

4. A clutch according to claim 3, wherein the cutting element further includes a stem perpendicular to the base and directed away from the cutting edge, to act as a rivet for securing the lining to the clutch plate.

5. A pressure plate comprising a support plate and a discardable face plate removably attached to the support plate.

6. A clutch plate provided with a lining and having a cutting element embedded in the lining, wherein the cutting element comprises a member which has a base and a cutting edge protruding from the base, the cutting element being housed in a mating recess provided for this purpose in the lining so that the cutting edge will emerge from the lining after a predetermined amount of wear of the lining to cut into and thereby damage the pressure plate of the clutch.

7. A clutch according to claim 6, wherein the cutting element further includes a stem perpendicular to the base and directed away from the cutting edge, to act as a rivet for securing the lining to the clutch plate.

8. A clutch substantially as herein described with reference to the accompanying drawings.

9. A pressure plate substantially as herein described with reference to Figure 1 of the accompanying drawings.

10. A clutch plate substantially as herein described with reference to the accompanying drawings.

11. A lining for a clutch plate substantially as herein described with reference to Figures 1, 2 and 4 of the accompanying drawings.

12. A cutting element substantially as herein described with reference to Figures 1, 3 and 4 of the accompanying drawings.