GB1044359A - Fluid pressure operable actuators - Google Patents

Abstract

1,044,359. Fluid-pressure brakes. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. Sept. 8, 1965 [Oct. 14, 1964; July 28, 1965], Nos. 41884/64 and 32239/65. Heading F2F. In a compressed-air actuator 1 for vehicle brakes, particularly one having two diaphragms 3, 7, as shown, or alternatively (Fig. 1, not shown, of the drawings accompanying the second Provisional Specification) having a piston 10 and a diaphragm 4, so as to provide two working chambers (4, 6 in the former case, and 12, 11 in the latter embodiment), escape of air from the actuator in the event of rupturing of diaphragm 3, or of the piston seal 16, is prevented by a valve comprising a closure element formed or carried by the diaphragm or piston. In the embodiment shown, the diaphragm 3 carries a flexible valve closure element 14 of annular form which is integral with a central portion 15 attached by a screw 16 to the diaphragm, the element normally covering an inlet opening 5. The element 14 acts as a one-way valve when the diaphragms are in the brakes-off position to which they are biased by a spring 11, so that the brakes may be applied by admitting air either to inlet 5 or to another inlet (not shown) communicating with the chamber 6. Once diaphragm 3 has been moved away from inlet 5, by the admission of air to chamber 4, element 14 no longer covers the inlet, so that release of the brakes can be effected, while if chamber 6 is pressurized instead of chamber 4 the element 14 remains in the position covering the inlet to guard against rupture of diaphragm 3. In the modification of Fig. 2 (not shown), of the drawings accompanying the first Provisional Specification, the diaphragm 3 itself acts as the closure element, the opening 5 being provided in a sleeve 21 which has a series of peripheral holes communicating with the chamber 4, these being covered by a resilient ring to provide a one-way valve, necessary to enable air to pass initially into the chamber 4 on pressurizing the inlet. Referring to the drawings accompanying the second Provisional Specification (not shown), the valve in the embodiment of Fig. 1 is provided by a resilient ring 22 inserted in a groove either in an end face of the piston 10 or in the adjacent cylinder end wall opposite the end face of the piston (Fig. 3). The ring 22 may be of U-section and supported on a radial flange carried by the piston (Fig. 2). Alternatively, an annular valve closure element 28 (Fig. 4) of dished cross-section secured to the end wall of the piston may directly cover the inlet 14 to the working chamber 12 of the piston. The actuator in this case includes an alternative manual applying means 20 for operation by a cable and which has a lostmotion connection with a sleeve 19 secured to a member 18 of the clamping assembly 5, 6, 18 for diaphragm 4 which provides the second working chamber 11. The effective area of the first chamber 12 may be varied by attaching a sleeve 23 of appropriate thickness to the piston.