Rotary hydraulic valve with pressure loaded seal - is unloaded when dog clutch actuator moves to open valve to minimise required turning moment

摘要

A rotary hydraulic valve has a cam actuator that ensures that hydraulic pressure is applied to gate valve seals to totally eliminate leakage in the closed position. The rotary gate valve is moved by a dog clutch coupling (10) consisting of a bottom plate (11) and a top plate (13) which operates as a piston and moves vertically under the action of a cam track (21) operating against a follower (22). The piston is rotated by the actuating lever. Fluid is supplied under pressure to top and bottom of the piston and also to either side of the seals. When closing the valve, the seal is not under pressure thus minimising the turning moment necessary. When closed the dog clutch moves a few degrees further to apply pressure on one side of the piston to give a total sealing action.