Abstract:
A hydraulic actuator adapted to be coupled to one or more pistons of a compressed air energy storage (CAES) system includes a housing forming a plurality of aligned bores, with a shaft disposed therein for reciprocating movement. For a three bore configuration, the shaft has three pistons subdividing the three bores into six pressure chambers. Four valves fluidically connected to the six chambers selectively provide pressurized hydraulic fluid, permitting three levels of hydraulic shaft force for each direction of shaft motion.