Piston operator

Claim 1

A VALVE ACTUATOR COMPRISING: FIRST AND SECOND CYLINDERS ARRANGED IN SIDE-BY-SIDE, PARALLEL RELATION AND FACING IN THE SAME DIRECTION, SAID CYLINDERS HAVING PORT MEANS AT ADJACENT ENDS FOR INFLOW AND OUTFLOW OF AN OPERATING FLUID; A FIRST PISTON RECIPROCABLE IN SAID FIRST CYLINDER AND A SECOND PISTON RECIPROCABLE IN SAID FIRST CYLINDER, EACH SAID PISTON BEING RECIPROCABLE IN SAID SECOND CYLINDER, EACH CLOSEST TO ITS RESPECTIVE PORT MEANS AND AN END POSITION FURTHEST FROM ITS RESPECTIVE PORT MEANS; A ROTARY MEMBER DISPOSED BETWEEN SAID CYLINDERS AND PISTONS TO ROTATE ABOUT AN AXIS TRANSVERSE TO THE LONGITUDINAL AXES OF SAID CYLINDERS; A TORQUE ARM HAVING A FIRST END AND A SECOND END, SAID TORQUE ARM BEING AFFIXED TO SAID ROTARY MEMBER INTERMEDIATE ITS ENDS WHEREBY ROTATION OF SAID TORQUE ARM IN A PLANE PERPENDICULAR TO THE AXIS OF SAID ROTARY MEMBER WILL ROTATE SAID ROTARY MEMBER, AND SLOT MEANS IN THE FIRST END OF SAID TORQUE ARM ENGAGING COMPLEMENTARY MEANS ON SAID FIRST PISTON AND SLOT MEANS IN THE SECOND END OF SAID TORQUE ARM ENGAGING COMPLEMENTARY MEANS ON SAID SECOND PISTON, SAID PORT MEANS AND THE CONNECTIONS OF SAID TORQUE ARM WITH SAID PISTONS BEING SO ARRANGED THAT, WHEN THE FIRST PISTON IS IN ITS START POSITION THE SECOND PISTON IS IN ITS END POSITION AND, AS OPERATING FLUID UNDER PRESSURE IS ADMITTED TO THE FIRST CYLINDER, THE FIRST PISTON MOVES TO ITS END POSITION AND THE SECOND PISTON IS MOVED BY SAID TORQUE ARM TO ITS START POSITION, SUCH MOVEMENTS BEING REVERSED UPON ADMISSION OF OPERATING FLUID PRESSURE TO SAID SECOND CYLINDER; THE CONNECTIONS BETWEEN SAID TORQUE ARM AND PISTON BEING SUCH THAT THE DISTANCE BETWEEN EACH SUCH CONNECTION AND THE AXIS OF SAID ROTARY MEMBER IS A MINIMUM AT A POINT INTERMEDIATE THE START AND END POSITIONS OF TRAVEL OF THE RESPECTIVE PISTONS, EACH OF SAID PISTONS COMPRISES A PISTON HEAD OF RELATIVELY SHORT AXIAL LENGTH, SEAL MEANS AROUND SAID PISTON HEAD, A SKIRT OF REDUCED DIAMETER PORTIONS OF SHORT AXIAL PISTON HEAD, AND ENLARGED DIAMETER PORTIONS OF SHORT AXIAL LENGTH FORMING THRUST BEARING MEMBERS AT THE LOWER END OF SAID SKIRTS, SAID THRUST BEARING MEMBERS BEING DISPOSED AT APPROXIMATELY THE LEVEL OF SAID COMPLEMENTARY ENGAGED MEANS AND BEING IN SLIDABLE ENGAGEMENT WITH OPPOSITE WALLS OF THE CYLINDERS TO TRANSMIT SAID THRUST OF SAID ENGAGED MEANS TO FIRST ONE OF SAID OPPOSITE WALLS AND THEN, WHEN SAID TORQUE ARM REACHES SAID INTERMEDIATE POINT, TO THE OTHER OF SAID OPPOSITE WALLS.