| 摘要 |
1,197,395. Seals. J. C. MONAHAN. 16 Aug., 1968 [9 Nov., 1967], No. 39420/68. Heading F2B. The housing of a fluid operated device 10 is provided with a plurality of shaft seals, as shown two 36, 37, contained in recesses 34 and fluid passageways 40, 42 controlled by valve means 50 for bringing the seals into operation in succession starting from the outermost seal 36. With the valve 50 open the inner seal 37 is exposed to fluid pressure on both sides so that the sealing lip 39 is not pressed into engagement with the rod 14. When the seal 36 becomes worn, the valve 50 is closed and the next seal 37 becomes operative. When hollow seals are employed instead, fluid pressure acting on one side only deforms them into engagement with the rod.
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