Patent ID: 8813786

Claim:
A hydraulic valve comprising: a valve body including: a passageway; supply, function and return ports communicating with said passageway by respective openings spaced apart along said passageway; and a valve member that is movable in and along said passageway to control fluid communication between said ports and includes a longitudinal internal passage extending within said valve member, said valve member carrying a lateral transverse shear seal in the form of a short cylinder which is integral with said valve member and engages said passageway; wherein, for one position of said valve member, said valve member isolates said function port from said return port and in another position of said valve member said shear seal communicates with said function port and provides fluid communication between said function port and said return port by way of said longitudinal internal passage within said valve member; wherein said valve member comprises a stepped rod which has portions of greater and lesser effective cross-sectional area section to each side of said shear seal and a recess between said portions; and wherein said supply port can communicate, in dependence on the position of said valve member, with said function port externally of said valve member, and said supply port supplies pressure to the outside of the valve member with said recess between said portions to produce a force tending to move said valve member towards said another position, said supply port being in communication with said function port for said one position of said valve member and out of communication with said function port for said another position of said valve member.