Oil volume compensation in a hydraulic circuit of a hydrostatic drive in an automotive working machine

The drive shaft connected to the engine (1) operates three pumps. The first pump (2) may be a variable capacity pump which is connected to control valves (8,9,19,20,21) and a hydraulic motor (7) which drives the wheels. The second (3) and third (4) hydraulic pumps supply oil to the circuit for the threshing machinery (22). A control valve (23) receives oil from the second and third pumps and apportions it to the threshing machinery.