Rotary actuator device

Claim 1

A ROTARY ACTUATOR DEVICE COMPRISING: A PAIR OF PARALLEL CYLINDERS; A FLUID-TIGHTLY SLIDABLE PISTON DISPOSED IN EACH CYLINDER AND SEPARATING EACH CYLINDER INTO A FIRST AND A SECOND CYLINDER PORTION; A CHAMBER FLUID-TIGHTLY SEALED ACROSS SAID FIRST CYLINDER PORTIONS AND PROVIDING COMMUNICATION THEEBETWEEN; AN OUTPUT SHAFT ROTATABLY MOUNTED IN SAID CHAMBER; A CHIN SPROCKET WITHIN SAID CHAMBER AND RIGIDLY MOUNTED TO SAID OUTPUT SHAFT, SAID CHAIN SPROCKET HAVING A PITCH DIAMETER SUBSTANTIALLY EQUAL TO THE AXIAL SEPARATION OF SAID PAIR OF CYLINDERS; A CHAIN MOUNTED OVER SAID SPROCKET, OPPOSITE ENDS OF SAID CHAIN BEING COUPLED TO ADJACENT ENDS OF SAID PAIR OF PISTONS; A CLOSURE MEMBER FLUID-TIGHTLY SEALING ACROSS SAID SECOND CYLINDER PORTIONS; AND CONTROL MEANS FOR CONTROLLING THE ROTATIONAL MOTION OF SAID OUTPUT SHAFT, SAID CONTROL MEANS APPLYING ACTUATING FLUID UNDER PRESSURE SIMULTANEOUSLY TO SAID CHAMBER AND A SELECTED ONE OF SAID SECOND PORTIONS WHILE THE NONSELECTED SECOND PORTION IS BEING COMMUNICATED WITH A LOW PRESSURE AREA, SAID CONTROL MEANS ALSO INCLUDING SWITCHING MEANS FOR SWITCHING THE SELECTED AND THEN NONSELECTED SECOND PORTION FOR REVERSE MOTION OF SAID OUTPUT SHAFT.