| 摘要 |
There is shown a hydraulic telescoping ram of the type suit- able to tip dump trucks and the like, which permits the use of outer aggressive seals and a bore sealing device by providing a conduit which hydraulically connects the upper end of each cylinder of the telescopic ram with an oil reservoir. This makes it possible to use seals which are not aggressive and which can run on surfaces of somewhat less than top quality, on the internal bottom faces of the rams so as to allow the passage of a small quantity of oil into a gap formed within the ram and cylinder and between the aggressive and non-aggressive seals. The oil which passes the non-aggressive seal is returned to the oil reservoir when the ram is extended.
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