| 摘要 |
<p>An hydraulic pump is disclosed for use in raising and lowering hospital beds, chairs and the like. Present devices used for raising the head or the foot of a bed require separate movements which have separate pedals or control means. The present hydraulic pump has only one operating control. The pump has a plunger slidingly located within a housing, a first valve means located between a reservoir and the housing which is adapted to allow fluid to be drawn from the reservoir into the housing during movement of the plunger in one direction. A second valve means is located within the housing and is adapted to allow fluid to flow from the housing during the greater part of plunger movement in the other direction. Means to control the second valve is provided at or near the completion of the plungers movement in the other direction to allow fluid to move back through the second valve means into the reservoir.</p> |
