Abstract: A hydraulic control valve comprising a housing fitted with an inlet port and an outlet port, a sealing port intermediate the inlet port and the outlet port, dividing the housing into an inlet chamber and an outlet chamber with a diaphragm sealingly dividing the outlet chamber and forming a first control chamber at one side of the diaphragm and comprising a first control port. A stem is connected to the diaphragm and is axially displaceable within the housing and a sealing member is fixed to the stem and is shiftable between a first position in which the sealing port is open and a second position in which the sealing port is closed. The housing further comprises a releasably retained partition plate sealingly dividing the outlet chamber so as to form a second control chamber at a second side of the diaphragm and a second control port, the plate having an opening for slidingly and sealingly supporting the stem.