| 摘要 |
<p>The servo-valve has a first stage, controlling a pressure medium on exceeding a preset pressure, while the overpressure main valve is actuated by a second stage, responding to the flow through the first stage. The first stage has a piston with a first section of uniform diameter over a preset length, and a second section of uniform diameter over a second preset length, the piston forming a control member. On under-reaching a preset pressure, a seat cooperates with the piston, having two diameters corresponding to the two sections. The first piston section forms a throttle, with the first seat section, while the piston second section forms a second throttle with the second seat section. Thus, the vertical motion of the control piston provides a progressively throttling flow of the pressure medium.</p> |
