Rotary Piston Type Actuator

A method of rotary actuation comprising:

• providing a rotary actuator comprising:
• a first housing defining a first arcuate chamber comprising a first cavity, a first fluid port in fluid communication with the first cavity, and an open end;
• a rotor assembly rotatably journaled in said first housing and comprising a rotary output shaft and a first rotor arm extending radially outward from the rotary output shaft;
• and an arcuate-shaped first piston disposed in said first housing for reciprocal movement in the first arcuate chamber through the open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, and a first portion of the first piston contacts the first rotor arm;
• applying pressurized fluid to the first pressure chamber;
• urging the first piston partially outward from the first pressure chamber to urge rotation of the rotary output shaft in a first direction;
• rotating the rotary output shaft in a second direction opposite that of the first direction;
• and,
• urging the first piston partially into the first pressure chamber to urge pressurized fluid out the first fluid port.