Hydraulic actuator for switching railway track points - uses electric motor running for short interval to pressurise hydraulic system and supply selected side of double active hydraulic cylinder

摘要

The actuator comprises a hydraulic circuit, a mechanical linkage between the hydraulic cylinder and the track rails, and an electric control circuit. The hydraulic system is pressurised by an electric motor driven pump which delivery hydraulic fluid to a dual acting hydraulic cylinder through a solenoid controlled three position control valve. The electric motor has an electronic timer circuit which allows it to run for five seconds, driving the pump which draws hydraulic fluid through a filter from a sealed reservoir. Solenoids control the operation of a distribution valve which directs hydraulic fluid to one side or the other of a double acting piston in cylinder. The piston displaces the track points through a mechanical link.