GB501449A - Improvements relating to means for rendering control systems irreversible - Google Patents

Abstract

501,449. Hydraulic locks ; operating aircraft control surfaces. EXACTOR CONTROL CO., Ltd., and GREEN, D. S. July 29, 1937, Nos. 21040/37 and 20034/38. [Class 69 (ii)] [Also in Group XXXIII] In a push-pull control system, especially for aircraft, of the kind in which a doubleacting piston works in a cylinder to displace liquid from one side of itself to the other, through passages controlled by valves, to inhibit forces applied to the receiver from reaching the transmitter, the receiver piston rod is secured to the piston and extends from one side thereof through one end wall of the cylinder, the transmitter piston rod extends through the other end wall of the cylinder and has a lost motion connection with the piston to operate the valves and thereafter move the piston, and both piston rods operate in tension and compression, the stoppage or restriction of liquid displacement when the valves close inhibiting movement of the receiver in that condition. A rod R connected to the controlled element or receiver is rigidly secured to a piston 7 disposed in a cylinder 1 filled with pressure liquid. Outwardly-opening lift valves 8, 9 are arranged in the ends of the piston with their stems close to a disc 13 on a controlling or transmitting rod T mounted with some lost motion in the piston 7. In use, the pressure liquid renders the piston immovable in the cylinder unless the transmitting rod T is operated whereupon the valves 8 or 9 are opened during the take up of the lost motion and thereafter liquid passes through the piston as the rod T displaces it. In a modification, the rod T actuates a slide valve to permit the liquid to flow through the piston and the valve orifices may be tapered and overlap slightly to give the locked piston a small degree of freedom. According to the second Provisional Specification, the cylinder and piston may be replaced by a pressure chamber of arcuate or circular form with a fixed radial wall and an angularly moving vane, the valves being mounted in the vane.