Arrangement for effective oil supply to a working chamber (34) in a hydrodynamic coupling (16) flushed through with oil, and lubrication of the bearings (12, 9) of the coupling. The working chamber is supplied with oil through a channel (14) in the stationary part (10) of the coupling (16) via a main bearing (12) forming part of the coupling and bearing the turbine (30) in the pump wheel (8). A second main bearing (9) bearing the pump wheel (8) in the stationary part (10) receives a continuously limited throughflow of lubricating oil via a throttle in communication with the flow of oil to the first main bearing (12). By means of the invention, a steady flow of oil to the working chamber of the coupling is obtained, and at the same time all the main bearings receive a continuous throughflow of lubricating oil which does not cause any great oil friction losses in the bearings during stationary running. The invention is advantageously applied to hydrodynamic couplings (16) in internal combustion engine units (1) of the compound type, where a turbine (3) driven by exhaust gas transmits surplus energy from the exhaust gases via the coupling (16) to the crankshaft (5) of the engine.