GB944090A - Improvements in or relating to declutching devices - Google Patents

Abstract

944,090. Controlling clutches and changespeed gearing; brakes. FRANCAISE DU FERODO S.A. June 26, 1962 [June 27, 1961; June 6, 1962], No. 24557/62. Headings F2D, F2E and F2L. An axially displaceable clutch thrust bearing is displaced by a pressure chamber having inlet and outlet valves under the control of a pilot mechanism, declutching being initiated by movement of the pilot mechanism to close the outlet valve before opening the inlet valve, the outlet valve being displaceable against a spring while remaining closed. A conventional single plate automobile clutch is released by a pedal operated release fork 34 which first contacts a valve stem 33 to seat outlet valve 31 against seating 55 on a spring loaded valve member 56. The valve spring 59 being weaker than the spring 60 allows the valve to remain closed, and prevent pressure air flow from pressure chamber 27 to exhaust 67, during further movement of the fork 34 which opens an inlet valve 30 between a pressure supply line 37 and the chamber 27. Pressure in the chamber 27 produces axial movement of a cylinder 20 carrying the valves and clutch thrust bearing 22 such that the clutch is released to an extent dependent on the movement of the fork 34. Selective fast or slow re-engagement of the clutch is provided by a two-way valve 68 leading to different area restrictors 69, 70. Since the fork 34 may butt against the ends of the valve bodies 36, 48, which are threaded into the cylinder 20, the pedal may always assist clutch release. The valve bodies may alternatively be bolted to the cylinder. In a second embodiment, Fig. 8, the stationary piston 26 of the pressure chamber 27 contains a second axially movable piston 75 restrained against rotation by splines 76 and carrying a brake lining 77 engageable against a face 78 rigid with a gear-box input shaft 15. On axial movement of the cylinder 20 sufficient for full clutch release, pressure from chamber 27 passes by passage 72 to a chamber 73 to apply the brake. In a modification, Fig. 9, the passage 72 is controlled by a valve 80 opening after lost motion D equal to clutch release, the dimension D being kept constant irrespective of clutch wear or adjustment by a sprag washer 84 acting on the valve stem 83. The pressure in the cylinder 20, Fig. 10, may be used to actuate a two-speed axle servo-piston 89 after change has been selected by a manual piston valve 85, the pressure being operative after it has reached a value sufficient to open a spring loaded valve 93.