Corrosion and contaminant resistant slide valve

摘要

A slide valve containing a ceramic apertured slide block slidably supported upon a pair of ceramic shear seals so that the slide can reciprocate between an operative and an inoperative position. A roof block also formed of a ceramic material is mounted over the slide block and a roller unit is positioned between opposing surfaces of the two blocks. Control pistons are mounted in cylinders on either side of the slide block. Control circuits are arranged to bring pilot fluid in a selected one of the cylinders to extend the piston housed therein against the slide thus changing the slide position. The control circuits are isolated from other circuits within the valve to prevent contaminants from adversely effecting poppet valves operatively associated with the control circuits.