Air-cooled internal combustion engine having a cooling air blower driven by a hydraulic coupling

In combination with an air-cooled internal combustion engine having a cooling air blower and a supply of lubricating oil;

• a hydrodynamic coupling operatively drivingly connected to said cooling air blower, and itself being driven by a portion of said oil as operating medium with the filling of said coupling with said oil being thermostatically regulated;
• the improvement comprising further adapting the filling of said coupling with oil to the atmospheric air pressure, and includes a coupling oil-supply line, which communicates said portion of said supply of lubricating oil to said coupling;
• a bypass additional filling line connected to said coupling oil-supply line to effect supplying additional oil to said coupling in response to a decrease in atmospheric air pressure;
• a regulator arranged in said bypass additional filling line for regulating flow of oil therethrough as a result of its position therein;
• and a barometric diaphragm operatively connected to said regulator for controlling the position thereof in said bypass additional filling line, said coupling being appropriately dimensioned to accommodate said additional oil.