Pressure unloading valve for hydraulic circuit - has spring loaded valve ball raised from spring loaded seat by fixed pin at predetermined circuit pressure

摘要

A hydraulic circuit unloading valve has a stepped bore whose larger diameter is sealed by a cover with an inward projection. Around the projection is a sliding sleeve contg. a seat and a valve ball spring loaded against the seat. The smaller diameter is sealed by a cap which holds a pin surrounded by a spring which urges the valve seat upwards against the ball. The fluid enters an axial bore in the cover and moves the sleeve against the force of the spring around the pin, this spring force being negligible for low fluid pressure. At higher fluid pressure the ball is urged against the seat, and at overpressure of the fluid the sleeve moves sufficiently against spring force for the pin to raise the ball from the seat and allow exhaust flow of fluid.