Patent GB-1009855-A (GB)
Title: Hydraulic brake valves
IPC: B60T11/28
Filed: 1962-05-16
Abstract: 1,009,855. Hydraulic brake valves.- H. TEVES, E. A. TEVES, and M. TAUSEND, [trading as ALFRED TEVES MASCHINENUND ARMATURENFABRIK KOMM. GES.]. May 16, 1962 [June 20, 1961], No. 18876/62. Heading F2F. An hydraulic brake valve for a power-assisted brake comprises a hollow control plunger 40 which co-operates with an actuating cylinder 32 displaceable in the valve casing 38 and with a non-movable valve sleeve 49 to form two valves, one of which controls communication between the wheel brake cylinders and the return and the other controls communication between a pressure medium source and the wheel brake cylinders. The interior of the actuating cylinder communicates with the wheel brake cylinders by way of aperture 43 and passage 42 and, after disengagement from the plunger 40 is connected via a passage to the return and is closed by a piston 33 adapted to be operated by a brake cylinder 7 controlled by a push rod 6. As shown the brake cylinder 7 having a piston 8 therein actuates two brake valves each of which act to connect a port 2 to a pressure medium source, e.g. an accumulator connected to a port 3 in communication with an annular chamber 45. A single return is connected to an annular chamber 4. To operate the brakes the push rod 6 is actuated which forces ring gasket 19 against the back of piston 8 to cut off communication between the working chamber 16 of the brake cylinder 7 from the return 4 which is by way of bore 17 and apertures 15. Pressure medium is displaced from chamber 16 to actuate piston 33 in its cylinder 32 so as to displace the pressure medium therein through aperture 43, passage 42 and passages 58 and thereby initially apply the brakes. The pressure medium which has been displaced from chamber 16 to act on the actuating cylinder 32 opens the valve 48, 49, once the force of spring 50 has been overcome, to connect the pressure accumulator to the port 2 via passages 46. Pressure medium from the accumulator forces piston 33 back until it abuts stop ring 35 so that a corresponding volume of pressure medium returns to the chamber 16 which forces cylinder 7 against the force of compression spring 11 until it abuts a stop 9. Further depression of the push rod 6 leads to stronger actuation of the actuating cylinder 32. Valve 48, 49 opens correspondingly further so that the accumulator pressure acting on the wheel brake cylinders is increased. Because of the increased pressure in chamber 16 the cylinder 7 moves further back to compress spring 10. On release of the brake the valve 48, 49 is closed by the spring 50 and the pressure medium flows to the return 4 via the valve 36, 51 which opens. If the piping extending to the wheel brake cylinders fractures the piston 33 applies a force to a valve rod 41 so as to force a circlip 56, Fig. 3, into a groove 55 and permit the valve rod to move so that the end face 54 and gasket 53 can seal the port 2. The leaking pipe is kept closed since the circlip 56 once it has passed catch 61 maintains the seal in operation. A non-return valve between port 3 and the accumulator ensures that the device 32, 33 acts as a master cylinder on pressure failure of the accumulator.