Patent ID: 7290509

Claim:
An actuator, comprising: a housing having first and second fluid ports; a stroke controller slideably disposed in the housing; first and second partial cylinders in the housing and the stroke controller, respectively, defining a longitudinal axis and having cylinder first and second ends in first and second directions, respectively; an actuation piston disposed between the first and second partial cylinders, the actuation piston having first and second surfaces moveable along the longitudinal axis; first and second actuation springs biasing the actuation piston in the first and second directions, respectively; a first fluid space defined by the cylinder first end and the first surface of the actuation piston; a second fluid space defined by the cylinder second end and the second surface of the actuation piston; a fluid bypass that short-circuits the first and second fluid spaces when the actuation piston does not overlap either of the first and second partial cylinders; a first flow mechanism in fluid communication between the first fluid space and the first port; a second flow mechanism in fluid communication between the second fluid space and the second port; a first supplemental flow mechanism in fluid communication between the first fluid space and the first port; and a second supplemental flow mechanism in fluid communication between the second fluid space and the second port.