Patent GB-508303-A (GB)
Title: Improvements in or relating to hydraulic control valve arrangements
IPC: B64C25/22
Filed: 1937-12-24
Abstract: 508,303. Interconnected valves. BRISTOL AEROPLANE CO., Ltd., and PONTING, R. Dec. 24, 1937, No. 35751. [Class 135] A hydraulic control valve arrangement comprises a normallyopen cut-off valve 14 controlling the flow of pressure liquid from a pressure main 19 to a conduit leading to a hydraulic motor, one or more control valves 11, 12, 13 controlling the supply of liquid from the main to other hydraulic motors and each connected with the cut-off valve 14 so that operation of any one of the control valves closes the cut-off valve, and means responsive to the pressure in the main which restore the cut-off valve to its open position when the said pressure attains a predetermined minimum value. The invention is described with reference to the hydraulic system of an aircraft in which the gun turret motors and motors for such parts as the retractable undercarriage, wing flaps and bomb doors are operated from a single source of pressure, and by its use, the gun turret circuit is cut out whilst one of the other parts is actuated. As shown, a body 10 has three rotary valves 11, 12, 13 which can be operated by arms 47, 48, 49 to connect motor ports 29 ... 34 selectively with a conduit 19 supplied with pressure liquid from a pump driven by the engine or with a discharge conduit 21. The conduit 19 is also connected to a passage 35 leading to the gun turret circuit by means of a rotary cut-off valve 14. Tappet arms 55, 56, 57 mounted on the valve spindles 16, 16, 17 have a lost-motion connection therewith due to the engagement of a lug 54 on each arm with a corresponding lug 53 on a collar 51 secured to the respective spindle. The tappet arms carry rollers 59, 60, 61 respectively engageable with cam members 62, 63, 64 carried by bell cranks 65, 66, 67 which are linked together by a bar 74. The latter is connected by a link 75 to an arm 76 on the spindle 18 of the cut-off valve 14. A spring 84 connected to the arm 76 urges the cut-off valve to the open position. The spindle 18 carries a further arm 77 which rests against a shoulder on a pivoted latch 73 urged counter-clockwise by springs 85 and linked to a bell-crank 81 which engages the piston-rod 43 of a spring- loaded piston 42 subject to the pressure in the conduit 19 through conduits 36, 38. On operation of one of the levers, say 47, the corresponding valve 11 is rotated and as its ports begin to open, the lost-motion of its spindle with respect to the tappet arm 55 is taken up and the cam 62 is displaced so as to close the valve 14 which is held closed by the engagement of the arm 77 with the end of the latch 78, as shown in Fig. 3. After the retractable undercarriage which is controlled by the valve 11 is operated, the pressure rises again in the conduit 19 and hence in the cylinder 40. At a predetermined pressure, the latch 78 is released and the spring 84 opens the valve 14. The reverse movement of the lever 47 operates the cam 62 in the same way. The valve 14 can be similarly operated by the arms 48, 49. If one of the control valves, say 13, is arranged to have its ports open between its end positions, the tappet arm 87 is made rigid with the spindle 17, Fig. 6, and engages a cam 88 formed on the bell-crank 66 of the preceding control valve. The annular movement of the tappet arms is limited by notched plates 86. The piston 42 may be replaced by a laminated capsule or diaphragm. According to the Provisional Specification, a reducing valve and a byepass valve may be used in the circuit of any device requiring a different pressure for its operation.