Anti-cavitation and overload relief valve for a hydraulic system

摘要

A hydraulic system including at least one hydraulic cylinder is provided with an anti-cavitation and overload relief valve having a housing, a first chamber within the housing in fluid communication with one end of the cylinder, and a second chamber within the housing in fluid communication with a fluid reservoir. A fluid passageway within the valve housing connects the first and second chambers. A movable valve assembly is positioned within the fluid passageway for operating in a plurality of modes for providing anti- cavitation and overload relief. The valve includes a stationary portion positioned within the fluid passageway between the first and second chambers having a valve seat. The movable valve assembly includes a poppet mechanism for sealingly engaging a valve seat of the movable valve element when the movable valve assembly is operating in first and third modes. A tang on the head of the poppet engages a reduced diameter portion of the stationary valve element in order to maintain fluid communication between the first and second chambers during the second mode of operation. An axial extension of a poppet spring seat limits the travel of the movable valve during the third mode of operation and limits the stress on a poppet spring.