| 摘要 |
A spool valve member (26) is slidable longitudinally within a bore 11, and has a first piston (28) at one end and a second piston (27) at the other end, the pistons being of equal size. High pressure fluid is continuously applied to a chamber 35 and against one face of the first piston 28, and low pressure is continuously applied chamber 34 and against the face of the second piston 27 which faces in the same direction as the face of the first piston to which high pressure is continuously applied. The other faces of the two pistons communicate with each other continuously, preferably through a passageway (40) in the valve body, with a control member, preferably in the form of a three-way valve (44), alternatively applying high or low pressure to these faces to move the spool valve member in one direction or the other, respectively. <IMAGE> |
