| 摘要 |
<p>A sealing system (12) for a hydraulic actuator (10) operable to selectively change the frictional sealing force exerted on a piston rod (22) in response to fluid pressure acting on the sealing system. A first seal member (72) operable for permitting a predetermined amount of fluid to leak from working chamber (16) to leakage chamber (76). A flow control valve (84) controls the flow of fluid from the leakage chamber (76) to a reservoir (86). A pressure responsive seal assembly (90) is operable to inhibit leakage of fluid from the leakage chamber (76) to the exterior of the hydraulic actuator (10) and is energizable in response to an increased fluid pressure within the leakage chamber (76) for generating increased frictional engagement with the piston rod (22) for preventing the vehicle body to sink during an extended stationary period of time. Furthermore, the pressure responsive sealing assembly (90) generates a reduced frictional engagement with the piston rod (22) when fluid pressure in the leakage chamber (76) is relatively low.</p> |
