Rotary actuator for use on machinery has screw engaging nut connected to flexible bag fixed in outer housing with supply of fluid under pressure

摘要

The outer housing of the actuator (1) is fixed and has a cylindrical middle portion (2) with thick closed ends (3,4) with sealed bearings (15,41) for a rotating drive shaft (24). Part of the shaft has a screw thread (17) which engages a female thread in a nut (13) which may move longitudinally but is restrained from rotation. A cylindrical fluid-tight flexible bag (25) has one end sealed to the nut and the other end sealed to the first end of the housing. Hydraulic fluid under pressure may pass through a connection (31,28) in the first end to inflate the bag. As the bag inflates it increases in diameter and becomes shorter, pulling the nut toward the first end. As the nut moves longitudinally, the shaft is made to rotate. Fluid outside the bag (8) leaves the casing via a bleed hole (48).