| 摘要 |
An hydraulic device includes a pump (14) and pressure cylinders (2,3) connected in series. Pistons (4,5) divide each cylinder into upper (8,10) and lower chambers (9,11) and have their piston rods (6,7) connected to, for example, a vehicle seat (1) to be raised or lowered. The upper and lower chamber of adjacent cylinders are interconnected and the pump (14) is connected with its main line (15) to the lower chamber (9) of a first cylinder (2) and with its return line (16) to the upper chamber (10) of the last cylinder (3) to raise the seat (1), and vice versa to lower the seat. A transfer valve (19) is connected in parallel between one line (15) from the pump and a line (12) between two cylinders to bypass the cylinder in event of a pressure build up beyond a predetermined level. Transfer valves may also be connected in parallel across other intermediate cylinders (if any). <IMAGE> |
