Abstract: A drive for a cooling fan at motor vehicles including a main cooling circuit and at least one secondary cooling circuit using a fluid friction clutch including a control element for the drive of the cooling fan is described. In case of a plurality of cooling circuits, such fluid friction clutches do not react as desired by actuating the cooling fan. To prevent this disadvantage, a drive for a cooling fan being drivable by a fluid friction clutch is to be provided, in which the cooling fan starts operation as soon as there is a requirement in at least one of the cooling circuits.

Abstract: A fan apparatus is disclosed which includes a fan coupled to a drive mechanism via a viscous clutch. The viscous clutch includes a drive chamber containing a hydraulic fluid with an amount of hydraulic fluid in the drive chamber being related to a torque transmitted from said drive mechanism to the fan; a valve coupled to the drive chamber controlling flow of hydraulic fluid into the drive chamber; a bimetallic strip coupled to the valve; and a heating element coupled to the viscous clutch close to the bimetallic strip. The bimetallic strip is located in a position open to ambient air.

Abstract: A drive for a cooling fan at motor vehicles including a main cooling circuit and at least one secondary cooling circuit using a fluid friction clutch including a control element for the drive of the cooling fan is described.