Abstract: 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 and a second end. A ram is slidably and sealingly mounted in the bore for axial movement between 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 slidably 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 fluid between the pressure ring and the bore second end to resist movement of the ram toward the 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.

Abstract: 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 and a second end. A ram is slidably and sealingly mounted in the bore for axial movement between 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 slidably 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 fluid between the pressure ring and the bore second end to resist movement of the ram toward the 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.