Piston return mechanism

Claim 1

A HYDRAULIC FLIUD TRANSLATION DEVICE INCLUDING A CYLINDER BLOCK, A PLURALITY OF PISTONS WITH INNER ENDS DISPOSED FOR RECIPROCATION WITHIN CYLINDERS IN THE BLOCK AND PROTRUDING THEREFROM AT ONE END OF THE BLOCK AN INCLINED CAM PLATE FACING SAID ONE END OF SAID BLOCK, A BEARING SURFACE ON SAID CAM PLATE, THE OUTER ENDS OF SAID PISTONS HAVING BEARING MEANS BEING ADAPTED TO SLIDABLY FOLLOW SAID BEARING SURFACE, MEANS MOUNTING SAID CYLINDER BLOCK AND CAM PLATE FOR RELATIVE ROTATION, INLET AND OUTLET MEANS COMMUNICATING SUCCESSIVELY WITH PORTS FROM SAID CYLINDERS UPON RELATIVE ROTATION OF THE CYLINDER BLOCK AND CAM PLATE, HOLD-DOWN MEANS ENGAGING SAID BEARING MEANS AND MOVABLE TOWARD AND AWAY FORM A POSITION RETAINING SAID BEARING MEANS IN ENGAGEMENT WITH SAID BEARING SURFACE, MEANS URGING SAID HOLD-DOWN MEANS TOWARD SAID POSITION RESPONSIVE TO RELATIVE ROTATION OF SAID CYLINDER BLOCK AND CAM PLATE AND MEAND BLOCKING SAID HOLD-DOWN MEANS FROM MOVEMENT GREATER THAN A PREDETERMINED DISTANCE AWAY FROM SAID POSITION DURING START-UP OF SAID DEVICE.