| 摘要 |
An actuator for use with a lift truck having an extendible mast includes an elongated housing and an axial bore formed in said housing. The bore has a first end a nd a second end. A ram is slidably and sealingly mounted in the bore for axial movement betwe en an extended position and a retracted position, and has one end disposed in the bore and an opposing end extending out of the bore second end. A pressure ring is slidab ly and sealingly mounted in the bore between the ram one end and the bore second end, wherein filling the bore with a fluid causes the ram to move from the retracted position toward the extended position, and engagement of the ram one end with the pressure ring traps flu id between the pressure ring and the bore second end to resist movement of the ram toward t he extended position. In a preferred embodiment the ram one end includes a piston plug body with an axial piston plug bore formed in the piston plug body. The piston plug bore has a first end and a second end, and the piston plug bore first end is in fluid communicati on with the bore formed in said housing. A piston is slidably and sealingly mounted in the piston plug bore, and has an end extending out of the piston plug bore second end toward the first end of the bore formed in said housing. An accumulator biasing memberurges the piston away from the piston plug bore second end.
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