Patent ID: 7299891

Claim:
A hydraulic drive mechanism for a mobile vehicle having at least first and second hydrostatic motors ( 7 , 9 ), each of the first and the second hydrostatic motors ( 7 , 9 ) being connected with a delivery exit ( 16 ) of a pressure-medium source ( 15 ) via a pressure-medium supply line ( 2 ) and a suction inlet ( 18 ) of the pressure-medium source ( 15 ) via a pressure-medium return line ( 3 ), the first and the second hydrostatic motors ( 7 , 9 ) both drive a common output shaft ( 11 ), and a plurality of pistons of the first and the second hydrostatic motors ( 7 , 9 ) are variably displaced via a displacement adjusting device ( 26 ) such that the rotational speed of the output shaft is variable; wherein each of the first and the second hydrostatic motors ( 7 , 9 ) is a radial piston motor which has a crankshaft that is operatively connected with the plurality of pistons located in cylinders of the radial piston motor, a stroke of each of the plurality of pistons being adjustable, during rotation of the crankshaft, by the adjusting device ( 26 ) such that when the crankshaft of the first hydrostatic motor ( 7 ) is driven above a maximum admissible driving rotational speed the pistons of the first hydrostatic motor ( 7 ) effect substantially no stroke in the cylinders and the pressure-medium supply line ( 2 ) is separated from the delivery exit ( 16 ) and connected with the pressure-medium return line ( 3 ) so that pressure which acts upon the pressure-medium return line ( 3 ) and upon the pressure-medium supply line ( 2 ) is the pressure which acts upon one of a suction inlet ( 18 ) of the pressure-medium source ( 15 ) or in a return line ( 30 ) from a radiator ( 31 ) to a tank ( 29 ) or in a feed pressure line so that the crankshaft of the first hydrostatic motor ( 7 ) can be driven at rotational speed higher than the maximum admissible driving rotational speed, and the crankshaft of the first hydrostatic motor ( 7 ) and the crankshaft of the second hydrostatic motor ( 9 ) are both permanently connected to the common output shaft ( 11 ) so as to continuously rotate with the common output shaft ( 11 ).