| 摘要 |
<p>A hydraulic seat cushioning device comprising a cylinder body and a piston has a concentric post-like upward projection in the cylinder body with a cylindrical surface in which there are a pressure fluid port and a vent port. An annular valving element closely slidably surrounding the post-like portion covers those ports when in a normal position but uncovers the vent port when above that position and uncovers the pressure fluid port when below it. The piston is so connected with the valving element as to move independently thereof in a lower portion of its stroke, but through the remainder of the piston stroke the valving element is constrained to move with the piston.</p> |
