Hydrostatic transmission

Claim 1

A VARIABLE SPEED HYDROSTATIC TRANSMISSION FOR DRIVING A ROTATABLE LOAD FROM A PRIME MOVER COMPRISING A FLUID MOTOR HAVING A STATIONARY CYLINDER BARREL WITH A PLURALITY OF CYLINDERS THEREIN, PISTONS RECIPROCABLE IN EACH OF SAID CYLINDERS, AN OUTPUT SHAFT ADAPTED TO ROTATABLY DRIVE SAID LOAD, A CAM PLATE ON SAID OUTPUT SHAFT ADAPTED TO BE ROTATED BY SAID PISTONS ON THEIR OUTWARD STROKES AND TO RETURN SAID PISTONS ON THEIR INWARD STROKES, A VARIABLE VOLUME PUMP ADAPTED TO BE DRIVEN BY SAID PRIME MOVER, A PRESSURE COMPENSATED CONTROL ADAPTED TO VARY THE VOLUME OF SAID PUMP, PRESSURE AND EXHAUST CONDUIT MEANS INTERCONNECTING SAID PUMP AND SAID MOTOR, VALVE MEANS HAVING PRESSURE AND EXHAUST ZONES CONNECTED TO SAID CONDUIT MEANS AND ADAPTED TO SEQUENTIALLY ALTERNATIVELY CONNECT SAID CYLINDERS WITH SAID ZONES, SAID MOTOR HAVING A ROTATABLE INPUT SHAFT ANGULARLY MOVABLE WITH RESPECT TO SAID OUTPUT SHAFT AND ADAPTED TO OPERATE SAID VALVE MEANS, AND CONTROL MOTOR MEANS TO ROTATE SAID INPUT SHAFT WHEREBY FLUID PRESSURE FROM SAID PUMP DRIVES SAID LOAD WHEN SAID INPUT SHAFT LEADS SAID OUTPUT SHAFT AND APPLIES A BRAKING FORCE ON SAID LOAD WHEN SAID INPUT SHAFT LAGS SAID OUTPUT SHAFT AND SAID PRESSURE COMPENSATED CONTROL VARIES THE PUMP VOLUME IN RESPONSE TO THE VOLUME OF FLOW THROUGH SAID MOTOR TO MAINTAIN SUBSTANTIALLY CONSTANT PRESSURE IN SAID PRESSURE CONDUIT MEANS.