Braking system for piston in double acting jack - comprises throttle valve to retard evacuation piston chamber and has two magnetic field switches to sense travel direction

摘要

A braking system is used for the end of travel of a piston in a double acting jack. The jack systemis used to open or close automatic gates and the braking system slows down the operation at the end of travel to stop the gates slowly. A double actingjack (1) has a piston (2) coupled to a shaft (3). The two chambers (A, B) are connected by pipes (4, 5) and via electrovalves (6, 7) to a fluid under pressure (P). These valves are switched to supply fluid to the respective chamber and their outlets are connected by pipes (9, 10) containing fluid under pressure to an electrovalve (12) operated by two magnetic field switches (15, 16) which sense the direction of travel of the piston. A throttle valve (13) acts to slow down time taken for fluid to evacuates a chamber.