| 摘要 |
A pressure-fluid operated actuator comprises a cylinder (10), two end walls (11, 12), located at opposite ends of the cylinder, and three pistons (15, 16, 17), mounted on an axially displaceable and rotatably journalled piston rod (14) and consisting on the one hand of two outer pistons (15, 17) which are mounted in axially fixed positions on the piston rod (14) and define two outer working chambers (23, 26), each of which being located adjacent to one end wall (11, 12), and on the other hand an inner piston (16) which is located between the two outer pistons (15, 17) and arranged in thread engagement with the piston rod (14) and which is locked against rotation thereof relatively to the cylinder (10) and defines two inner working chambers (24, 25), located each between the inner piston and one of the two outer pistons (15, 17). Each inner working chamber (24, 25) is connected to a pressure-fluid duct comprising a first portion (41, 44), having a variable effective length in the longitudinal direction of the piston rod (14) and extending through one of the two outer working chambers (23, 26) from a through passage (40, 43), provided in the adjacent end wall (11, 12), and a second portion (42, 45) which is provided in a member (15, 17), axially moveable in unison with the piston rod (14), and which terminates in said inner working chamber (24, 25). |
