GB1353009A - Brake systems - Google Patents

Abstract

1353009 Brake systems; valves BENDIX WESTINGHOUSE Ltd 22 June 1971 [17 Aug 1970] 39474/70 Headings F2F and F2V A brake system includes a spring-applied actuator and an air-applied actuator which actuators are respectively controlled by the pressures at two outlet ports 102, 302 of a fluid pressure control device, the device incorporating an inlet port 2 from a pressure source and two self-lapping valves I, III which on actuation by a cam 200 serve to control the pressures at the outlet ports 102, 302 to thereby actuate or deactuate either or both of the actuators to control the brakes. The cam 200 is operated by a control member 206, 216, 209 movable between two locations 214, 215 to set each valve to supply a pressure at its outlet port 102 or 302 in dependence upon the position of the member between the locations 214, 215, the pressure at one outlet port being variable inversely with respect to that at the other outlet port, and the control member also being movable to a third location 213 at which the cam 200 is operable to set each valve to connect its outlet port 102, 302 to a single exhaust 3. As shown, the two valves are identical and the valve I comprises a cam follower 104 having a valve seat 117 co-operable with a closure on a conduit 115 leading to the exhaust port 3 : the conduit 115 is rigidly attached to a piston 114 movable within a further piston 110 formed of two parts 111, 112. The part 112 has a valve seat 116 co-operable with a closure on piston 114. The common inlet port 2 is connected to a cavity 122 between pistons 114, 110 by a radial aperture 123 in piston 110. The cam 200 which acts on the cam followers 104, 304 to control the valves I, III to thereby alter the pressure at the outlet ports 102, 302 is movable both rotationally and axially and includes a pair of trunnions 202 on its upper surface in which a pivot pin 203 is mounted. A first cap member 204 is mounted for free rotational movement on the upper surface of the device and is held in place by a second outer cap member 205. The first cap member 204 receives an operating member 206 and is provided with a pin 207 on which member 206 can pivot, and the member 206 passes between the trunnions 202 and has a hole 211 for passage of pin 203. The member 206 has a handle 216 which passes through a slot in the first cap 204 and an L- shaped aperture 208 in the second cap 205 which aperture 208 defines the three locations 214, 215, 213, and also constrains the member 206 either to rotate about the axis of the cam 200 or to be displaced along the axis of rotation of the cam 200. The handle 216 has a detent 209 which co-operates with bevelled surfaces between locations 214, 215 to hod the handle 216 in any selected position therebetween. By pulling the detent 209 towards the knob 217 the handle 216 can be moved to the third location 213 which may represent a "PARK" position. The cam 200 may have a face cam or an edge cam and various modes of movement of the cam are possible depending on the aperture which may also be N-shaped or U-shaped.