Abstract: An improved actuator of the type in which a piston is translatable in a piston housing in response to an expandable working fluid in fluid communication with one end of the piston. An improved sealing assembly prevents leakage of working fluid from the piston housing.

Abstract: An improved electrothermally operated actuator of the type in which a piston is translatable in a piston housing in response to electrical heating of an expandable working fluid in fluid communication with one end of the piston. The working fluid is at least partially disposed in a tube assembly which is connected in an electric circuit which is closed and opened, in response to selected events, to heat or cool the working fluid to effect movement of the piston between retracted and extended terminal positions. An improved sealing assembly prevents leakage of working fluid from the piston housing. The actuator may be connected through a power translating assembly to a rotating element of an operable device translating linear movement of the actuator to rotating movement of the rotating element.