ACTUATOR ASSEMBLY

摘要

An actuator assembly is used for breaking a crust that forms during the smelting of aluminium. The assembly (1) comprises a fluid-pressure- operated cylinder (2) in which works a piston (3) attached to a piston rod (4). The piston rod (4) has a piercing tip at its free end for breaking the crust. The piston (3) is adapted to be driven to a retracted position by supplying fluid to a front side (11) and to an extended position by supplying fluid to a rear side (10). The assembly (1) also includes sensing means (9) to determine when the piston (3) is in the extended position and cause it to return to its retracted position, and automatic retraction means (15) causing the piston (3) to move to the retracted position after a predetermined time if the extended position has not been reached following the supply of fluid to the rear side (10). The assembly may also include monitoring means to monitor the position of the piston (3), and retention means (63) for retaining the piston (3) in the retracted position.