Abstract: An electro-hydraulic valve actuator comprising an actuator casing; a piston/rack means in the casing having walls reciprocating linearly to effect linear movements, the reciprocating walls defining a center chamber therebetween and two outside chambers inside the casing; an output shaft in communication with the piston/rack means for driving a valve, the output shaft effecting rotational movements in response to the linear movements of the piston/rack means; resilient return means in each of the two outside chambers engaging the reciprocating walls of the piston/rack means and inner end walls of the casing, the resilient return means biasing the reciprocating walls of the piston/rack means to a closed position; a pumping means; a primary internal flow path for transferring hydraulic fluid from the pumping means to a first output port and into the center chamber, the hydraulic fluid in the center chamber causing the piston/rack means to expand in the casing to transmit the linear movements to the output shaft;