GB937765A - Improvements in or relating to hydraulic actuating mechanisms - Google Patents

Abstract

937,765. Hydraulic apparatus. ARMSTRONG PATENTS CO. Ltd. Jan. 16, 1961 [July 22, 1960], No. 25535/60. Class 69 (2). An hydraulic actuator comprises a piston 9 displaceable in a chamber having inlet and outlet ports 8a, 8c leading to opposite sides of the piston, and a controlled passage 8e between the inlet and outlet ports by-passing the piston. The actuator has coaxial cylinders 5, 6 having a space 19 therebetween connected by a port 5a to the right-hand side of the piston and by a passage 8d to the port 8c. The left-hand side of the piston is connected by a passage 8b to the port 8a. The control passage 8e is connected by a passage 8g to the chamber at the left of the piston and intersects the passage 8d and an adjustable screw 11 control the communication between the passages 8d and 8e. The actuator may act as a pump or motor and two similar actuators may be connected together by a pair of pipes between their ports to act as a telemotor system. With the screws of the actuators closing the passages, the movement of one piston will cause a corresponding movement of the other. When a controlled passage is opened by unscrewing the screw, one piston can be moved without moving the other, the fluid by-passing the piston. To fill the actuators, a T-junction is provided in each pipe and with the screws open, fluid is supplied to one pipe and air exhausted from the other while the pistons are reciprocated. Means may be provided connected to a reservoir to compensate for changes in the volume of the fluid as a result of temperature changes.