Patent GB-1005195-A (GB)
Title: Improvements in and relating to clutch operating mechanism
Inventor: CHOUINGS LESLIE CYRIL
IPC: F16D25/12
Filed: 1962-06-26
Abstract: 1,005,195. Hydraulic motors. AUTOMOTIVE PRODUCTS CO. Ltd. June 20, 1963 [June 26, 1962], No. 24535/62. Heading F1P. [Also in Division F2] In a fluid pressure-operated clutch-adjusting mechanism consisting of a piston 5, Fig. 1, connectable, e.g. by a rod 6 to the clutch and slidable in a cylinder 1 upon admission of pressure fluid thereto, the length of the piston stroke is maintained constant by means of an automatic adjusting device comprising a doublelip seal 7 surrounding the piston to frictionally engage it so as to be axially movable jointly with it during a predetermined part of its working and return strokes, axially spaced stops 9, 11 limiting the joint axial movement of the seal 7 with the piston 1 and resilient means 10 urging the seal 7 towards the stop 9 when the piston is in the position corresponding to clutch engagement, excess movement of the piston during a working stroke, e.g. as a result of wear of the clutch friction linings, resulting in repositioning the seal 7 axially on the piston by an amount corresponding to said excess movement. The seal 7 has its lips normally in frictional engagement with the piston and cylinder wall. Stop 9 is provided by the inner shoulder of the cylinder counter bore 8 and stop 11 by a washer axially located by a retaining ring 1 A. The resilient means consists of a compression spring 10 held between the washer 11 and a cup mem= ber 12 axially spaced from the washer 11 by a predetermined clearance when the lip seal 7 is urged into contact with the shoulder 9 with the piston 5 in its fully retracted position corresponding to clutch engagement. To disengage the clutch, hydraulic fluid is introduced in the cylinder via a port 2 and the seal 7 moves jointly with the piston until the outer end of the cup member 12 abuts the washer 11. At this point the rod 6 effectively operates disengagement of the clutch, the piston completing its working stroke by moving relatively to the seal. If additional movement of the piston beyond its initial stroke, and hence beyond its normal stroke, takes place due to clutch wear, the seal 7 will become repositioned on the piston by an amount, corresponding to the additional movement whereby, when the clutch re-engages, the piston 5 retracts to a new position short of its previous position by an amount corresponding to the additional movement. In Fig. 2, the axially outer stop is provided by an end wall 22 which is dished outwardly to provide a clearance 23 between itself and a spring washer 24. On the working stroke, the hydraulic fluid also acts on the seal 20 so that the latter is deformed both by the fluid pressure and the piston drag on it, to conform to the dished formation of the end wall. On the return stroke the seal remains deformed until the hydraulic pressure reduces sufficiently to permit it to regain its normal shape under its own resilience assisted by the spring washer, the seal movement completing the return stroke of the piston while the fluid pressure retains the grip of the seal on the piston.