Patent ID: 7341026

Claim:
A drive train system comprising: a driving engine; a cooling system for cooling the driving engine, wherein the cooling system comprises a coolant circuit, a cooling device and a fan in thermal communication with the cooling device, wherein the fan is powered by the driving engine; a clutch operably connected to the driving engine and the fan, wherein the controllable clutch is a hydrodynamic clutch comprising a primary wheel and a secondary wheel which define a working chamber; a working fluid supply system in fluid communication with the working chamber for supplying a working fluid thereto; and a clutch controller for controlling the hydrodynamic clutch, wherein the working fluid supply system comprises a circuit that is coupled to the working chamber and has a filling controller for controlling a filling ratio in the working chamber, and wherein the circuit is a closed circuit having a pressure-tight seal with a pressure-tight closed working fluid reservoir and the filling controller applies a static superimposed pressure on the working fluid in the working fluid reservoir.