| 摘要 |
An improved seal (1) used in a hydraulic system having a piston rod (7) in a housing (5). The seal has stressing and sealing members (15, 17) with the latter being in point contact (23) with a piston rod un- der low fluid pressure and an additional point contact (29) with the piston rod under high fluid pressure. A shallow concavity (27) be- tween point contact (23) and the contact area entraps lubricating fluid when the seal is subjected to high fluid pressure. In another modifica- tion, the sealing member (17) has an incline (35) on the face in contact with stressing member (15). Thus, under high fluid pressure, stressing member (15) is forced up the incline (35), exerts increased pressure through the sealing member against the contact area and produces a high fluid pressure seal. In another embodiment, the sealing member (17) has a concave surface (25) to receive stressing member (15) such that it is centered, during low pressure operation, over a sealing con- tact area of the sealing member (17).
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