Patent ID: 7614226

Claim:
A hydraulic transmission system comprising: a first radial piston hydraulic motor ( 1 ) which adjustably displaces a first volume of pressure medium for driving an output shaft ( 3 ), and a second radial piston hydraulic motor ( 4 ) which adjustably displaces a second volume of the pressure medium for driving the output shaft ( 3 ); the first radial piston hydraulic motor ( 1 ) communicates with a valve ( 9 ) via a pressure medium supply line ( 11 ) and a pressure medium return line ( 12 ); a hydraulic pump ( 6 ) communicates with the valve ( 9 ) via a conveyor line ( 7 ) and a suction line ( 8 ); the valve ( 9 ), in a first switching position, connects the conveyor line ( 7 ) with the pressure medium supply line ( 11 ) and the suction line ( 8 ) with the pressure medium return line ( 12 ); the valve ( 9 ), in a second switching position, connects the pressure medium supply line ( 11 ) and the pressure medium return line ( 12 ) with a pressure medium reservoir ( 14 ); the valve ( 9 ) is electrically actuated to switch from the first switching position to the second switching position and from the second switching position to the first switching position only when substantially none of the first volume of pressure medium is displaced by the first hydraulic motor ( 1 ).