Patent GB-528176-A (GB)
Title: Improvements in or relating to hydraulically operated brake mechanisms
IPC: B64C25/44
Filed: 1939-02-11
Abstract: 528,176. Landing wheel brakes. INDIARUBBER, GUTTA PERCHA & TELEGRAPH WORKS CO., Ltd., TARRIS, F. J., and WEBB, D. Feb. 11, 1939, No. 4557. [Class 4] [Also in Group XXXIV] Hydraulic brake apparatus for vehicle and aircraft wheel comprises a valve for regulating the pressure supply to the brakes, the valve having a'valve head at one end adapted to rest on a seating provided by the valve chamber and a balancing piston at the other end slidable in the valve chamber thus providing a balanced valve. Means for effecting differential braking for steering similar to that described in Specification 469.407 may be provided. The apparatus shown comprises a main control device 10 adapted to establish pressure for operating a pair of similar auxiliary control devices 11 which supply pressure fluid respectively to the wheel brakes at the two sides of an aircraft, the devices 11 being also capable of separate control for steering. The stem 17 of the supply valve 16 of the device 10 is formed with a balancing piston 18, the fluid supply from pipe 44 entering by ports 28 between the valve and piston. The valve is operated by the exhaust valve 31 through a slidable grooved member 19. The valve 31 has a resilient seat-engaging part 50 and is operated by cable 47, lever 48, plunger 35 and a spring 41. A chamber 34 is connected by passage 46 and chamber 40 to an exhaust pipe 45. Normally the operating chamber 69 to each auxiliary device 11 is connected to the chamber 34 by passages 83, 54, exhaust valve chamber 29 and passage 32. Operation of the plunger 35 seats the valve 31 by the yielding of the valve part 50, and opens the valve 16 supplying pressure liquid to the chamber 69 of the auxiliary devices 11 through chamber 23 and passages 51, 83. When the fluid pressure thus established acting on the member 19 is sufficient to overcome the spring 41 the valve 31 moves back sufficiently to allow the valve 16 to re-close but without itself leaving its seat. The pressure established in the chamber 69 is thus dependent upon the movement of the plunger 35. The periphery of the valve 31 is grooved to provide a restricted passage for liquid between the front and rear parts of its chamber 19, so that a dashpot action is obtained and prevents chatter of the valve. Each auxiliary device 11 has a similar supply valve 57, 58, 59 operating member 65 and exhaust valve 67. The stem 72 of the valve 67 in this case telescopes into a piston 70 and a spring 73 is disposed between the piston and the valve. The spaces 75 and 65<1> in front of the valve 57 and behind the valve piston 59 are connected together and to the pipe 78 leading to the brake. The space 68 is connected to the exhaust chamber 34 and with the valve 67 unseated as shown, and space 65<1> is connected to space 68 so that the brake is connected to exhaust. When by operation of the device 10 pressure is established in chamber 69 the valves 57, 67, are operated by the piston 70 in a similar manner to that of the valves 16, 31 to establish a pressure in chamber 69. To effect differential braking for steering the aircraft, a spindle 80 is provided having a pair of forked arms, adapted to engage respectively the pistons 70 of the two devices 11 (the end 82 of one which is shown). One or other of the pistons can thus be pressed back against the hydraulic pressure in its chamber 69, to reduce the pressure in the corresponding brake.