Drive train of a vehicle, especially a mobile working machine

The train (1) has a working hydraulic system (4) comprising a hydraulic pump (7) that is propelled by an internal combustion engine (2). A feed pump (20) is propelled by the combustion engine for supplying a feed circuit (23). The feed pump is operated as a pump and a motor. The feed pump is operated with a suction side pressure medium that is obtained from a container (9), and is guided into a supply pressure spacer (22) that supports the feed circuit. The feed pump is supplied at the suction side pressure medium from a pressure fluid accumulator (25) in an engine operation.