Electro-hydraulic controls for power drive system

Claim 1

IN A SYSTEM FOR DRIVING A LOAD FROM A PRIME MOVER, THE COMBINATION COMPRISING A TRANSMISSION HAVING INPUT AND OUTPUT SHAFTS ADAPTED FOR COUPLING RESPECTIVELY TO THE PRIME MOVER AND THE LOAD, SAID TRANSMISSION HAVING MEANS INCLUDING FIRST AND SECOND CLUTCHES RESPECTIVELY ENGAGEABLE TO PRODUCE FORWARD OR REVERSE DRIVE OF SAID OUTPUT SHAFT RELATIVE TO THE DIRECTION OF ROTATION OF SAID INPUT SHAFT, FIRST AND SECOND ELECTRICAL ACTUATORS AND MEANS RESPONSIVE TO EXCITATION THEREOF FOR RESPECTIVELY ENGAGING SAID FIRST AND SECOND CLUTCHES, MEANS INCLUDING FIRST AND SECOND CONTROLLABLE SWITCHING DEVICES IN FIRST AND SECOND ELECTRICAL CIRCUITS FOR SELECTIVELY EXCITING AND FIRST AND SECOND ACTUATORS, FIRST AND SECOND DIRECTION SELECTOR CONTROL MEANS FOR APPLYING CONTROL SIGNALS TO SAID FIRST AND SECON SWITCHIN DEVICES TO RENDER THE LATTER SELECTIVELY AND COMPLEMENTALLY CONDUCTIVE, MEANS FOR SENSING AND SIGNALLING WHEN SAID OUTPUL SHAFT IS TURNING IN A GIVEN DIRECTION WITH A SPEED GREATER THAN A PRREDETERMINED VALUE, AND MEANS RESPONSIVE TO SIGNALLING BY SAID SENSING MEANS RENDERING ONE OF SAID SWITCHING DEVICES IMMUNE TO THE CONTROL SIGNALS FROM SAID SELECTOR CONTROL MEANS, SAID ONE DEVICE BEING THAT WHICH IN ITS CONDUCTIVE STATE RESULTS IN DRIVE OF SAID OUTPUT SHAFT IN A DIRECTION OPPOSITE TO SAID GIVEN DIRECTION.