| 摘要 |
A hydraulic unloader valve comprises a body (14) having an inlet (1), a delivery outlet (2) and a by-pass outlet (3). The inlet is connected to the by-pass outlet through a passage (22) which is generally closed by means of a control valve (20). The control valve is operated by a three way pilot (15, 17) which is movable between two terminal positions. Upon commencement of a change of the state of the pilot valve from one terminal position to the other terminal position, the change of state is completed and the pressures at which the change of state commences from each of the terminal positions is appreciably different. |
