The hydrostatic transmission has a hydrostatic torque-converter (4C) with two hydrostatic units (A,B) of variable vol. and constant vol. respectively, the delivered power being divided between hydraulic and mechanical paths, with subsequent summation at the transmission output. One or more blocking devices (KH,KB) is switched in at defined transmission ratios for blocking the constant vol. hydrostatic unit and/or a given range under manual and/or automatic control.