Constant speed drives

Claim 1

IN A MECHANICAL CONSTANT-SPEED DRIVE FOR TRANSMITTING DRIVING POWER FROM A VARIABLE-SPEED ENGINE TO AN ELEMENT TO BE DRIVEN AT A CONSTANT SPEED, THE COMBINATION COMPRISING A VARIABLE-SPEED AIR MOTOR OF THE POSITIVEDISPLACEMENT TYPE, A PRESSURE-FLUID SUPPLY CONNECTION, AN ATMOSPHERIC CONNECTION, A DIFFERENTIAL GEAR DRIVE HAVING THREE LEGS RESPECTIVELY DRIVINGLY CONNECTED TO THE ENGINE, THE AIR MOTOR AND THE ELEMENT, FLOW-CONTROL MEANS RESPONSIVE TO THE SPEED OF SAID ELEMENT AND CONNECTED TO THE AIR MOTOR, THE PRESSURE-FLUID SUPPLY CONNECTION AND THE ATMOSPHERIC CONNECTION, SAID SPEED-RESPONSIVE FLOWCONTROL MEANS BEING OPERATIVE TO SO CONTROL THE FLOW OF FLUID FROM SAID CONNECTIONS THROUGH THE MOTOR AS TO CAUSE THE AIR MOTOR TO OPERATE IN ONE DIRECTION TO SUPPLEMENT THE ENGINE-DERIVED SPEED OF THE ELEMENT WHEN THE ENGINE SPEED IS BELOW A PRE-DETERMINED VALUE, AND TO SO CONTROL THE FLOW OF AIR THROUGH THE AIR MOTOR AS TO CAUSE THE AIR MOTOR TO RUN IN THE OPPOSITE DIRECTION TO REDUCE THE SPEED AT WHICH THE ELEMENT IS DRIVEN BY THE DIFFERENTIAL GEAR DRIVE BELOW THE ENGINE-DERIVED SPEED WHEN THE ENGINE SPEED IS HIGHER THAN THE SAID PRE-DETERMINED VALUE, AND A GEAR TRAIN BY-PASSING PART OF THE DIFFERENTIAL GEAR DRIVE AND DRIVINGLY INTERCONNECTING THE AIR MOTOR AND THAT LEG OF THE DIFFERENTIAL GEAR DRIVE WHICH IS DRIVINGLY CONNECTED TO THE ELEMENT, SAID GEAR TRAIN INCLUDING AN OVERRUNNING CLUTCH WHICH ENGAGES ONLY WHEN THE SPEED SUPPLIED TO THE ELEMENT THROUGH THE GEAR TRAIN IS GREATER THAN THAT SUPPLIED BY THE DIFFERENTIAL GEAR DRIVE, THE RATIO OF SAID GEAR TRAIN BEING SUCH THAT, THROUGHOUT A PREDETERMINED SPEED RANGE OF THE ENGINE INCLUDING SAID PREDETERMINED SPEED, THE SPEED SUPPLIED TO THE ELEMENT BY THE DIFFERENTIAL GEAR DRIVE IS GREATER THAN THE SPEED SUPPLIED BY SAID GEAR TRAIN.