GB531465A - Improvements relating to hydraulic actuating systems, for aircraft and the like - Google Patents

Abstract

531,465. Controlling aircraft; undercarriages. DOWTY, G. H. March 31, 1939, Nos. 10140 and 16844. [Class 4] [Also in Group XXIX] A hydraulic actuating system for aircraft and the like is described in connection with the actuation of undercarriage jacks 23, retractable radiator jacks 24, bomb door jacks 25, and flap jacks 26 by means of a common variable delivery pump 14 the output of which ceases when the output pressure reaches a pre-determined value. Examples of such pumps are described in Specifications 524,199 and 524,384, [both in Group XXVIII], and the invention covers the application to one jack only under control of a flow resistor means for raising the output pressure of the pump and thereby reducing its rate of delivery. A common outlet pipe 16 from the pump may be connected by means of control valves V, VI, V2, V3, to the jacks which are to be operated, or the valves may be set to connect the jacks to a return pipe 27 leading to a reservoir 11. An auxiliary hand-operated pump 18 may be arranged in the pump circuit and also a non-return valve 17. To prevent violent action of the smaller jacks resistance devices R, R1, R2, R3, R4, R5 are arranged in the supply and return pipes of the jacks 24, 25, 26. This may be effected by using smaller pipes, or valves with controllable passages, or by using a spring-controlled reduction valve 42, Fig. 7, with an aperture 45 selected in accordance with the use of jack to permit the fluid to operate the jack. The valve opens to allow of release of the jack. A hydraulically operated brake device may also be arranged in parallel with the jacks, its reservoir being charged by the pump 41 under control of a valve similar to the valves V-V3 the brake itself is under control of an additional valve.