A viscous clutch (20) includes a housing assembly (28), a rotor assembly (26), a reservoir (38) to hold a supply of a shear fluid, a working chamber (40) operatively positioned between the housing assembly and the rotor assembly, and a fluid return bore (26-1B) that optionally extends radially through at least an outer diameter portion of the rotor assembly to the working chamber. Selective introduction of the shear fluid to the working chamber facilitates selective torque transmission between the housing assembly and the rotor assembly. The fluid return bore can form at least a portion of a fluid return path (50) from the working chamber to the reservoir.

A viscous clutch (20) includes a housing assembly (28), a rotor assembly (26), a reservoir (38) to hold a supply of a shear fluid, a working chamber (40) operatively positioned between the housing assembly and the rotor assembly, and a fluid return bore (26-1B) that optionally extends radially through at least an outer diameter portion of the rotor assembly to the working chamber. Selective introduction of the shear fluid to the working chamber facilitates selective torque transmission between the housing assembly and the rotor assembly. The fluid return bore can form at least a portion of a fluid return path (50) from the working chamber to the reservoir.

A torque converter is disclosed. The torque converter includes a cover, an impeller, a turbine, a stator, and a first one-way clutch. A torque outputted from a prime mover is inputted to the cover. The impeller is unitarily rotated with the cover. The turbine is opposed to the impeller. The stator is disposed between the impeller and the turbine. The first one-way clutch is configured to make the cover rotatable relative to the turbine in a forward rotational direction. The first one-way clutch is further configured to rotate the cover unitarily with the turbine in a reverse rotational direction.

A viscous clutch head may be replaced by selecting a viscous clutch head and a mount adapter. The viscous clutch head and the mount adapter may be selected from a group of universal modular fan drives and from a group of mount adapters. The mount adapter of a threaded type or a flange and bolt type may be selected. Depending on the viscous clutch head to be replaced, a fan adapter and/or a pilot adapter may also be selected from a group of fan adapters and from a group of pilot adapters. Accordingly, a range of models of viscous fan clutch systems may be replaced by using a limited number of parts. These parts may be stored on a tool cart. As different models of viscous fan clutch systems may be replaced using a limited number of parts, the in-stock inventory of replacement parts may be reduced.

A viscous clutch head may be replaced by selecting a viscous clutch head and a mount adapter. The viscous clutch head and the mount adapter may be selected from a group of universal modular fan drives and from a group of mount adapters. The mount adapter of a threaded type or a flange and bolt type may be selected. Depending on the viscous clutch head to be replaced, a fan adapter and/or a pilot adapter may also be selected from a group of fan adapters and from a group of pilot adapters. Accordingly, a range of models of viscous fan clutch systems may be replaced by using a limited number of parts. These parts may be stored on a tool cart. As different models of viscous fan clutch systems may be replaced using a limited number of parts, the in-stock inventory of replacement parts may be reduced.

An internal combustion engine including a cooling liquid circuit, which is connected to a cylinder head and an engine block of the internal combustion engine and which includes a cooling liquid pump. The cooling liquid pump includes a drive shaft and is capable of conveying cooling liquid in the cooling liquid circuit. Further, the internal combustion engine includes a Visco clutch. The Visco clutch is arranged for the drive by the internal combustion engine. The Visco clutch includes a clutch fluid for torque transmission. At the output side, the Visco clutch is connected to the drive shaft of the cooling liquid pump. The drive shaft of the cooling liquid pump include at least one heat pipe. The heat pipe is in heat exchange with the clutch fluid as a heat source and the cooling liquid as a heat sink.

A torque converter is disclosed. The torque converter includes a cover, an impeller, a turbine, a stator, and a first one-way clutch. A torque outputted from a prime mover is inputted to the cover. The impeller is unitarily rotated with the cover. The turbine is opposed to the impeller. The stator is disposed between the impeller and the turbine. The first one-way clutch is configured to make the cover rotatable relative to the turbine in a forward rotational direction. The first one-way clutch is further configured to rotate the cover unitarily with the turbine in a reverse rotational direction.

A power transmission device according to an aspect of the present disclosure includes a first drive unit having a first drive source, a first transmission connected to the first drive source and the driving force to be transmitted, a second drive source, and a second transmission connected to the second drive source and the driving force to be transmitted, and includes a second drive unit arranged in parallel with the first drive unit, and a frictional differential limiting element disposed between the first transmission and the second transmission and limiting a differential between the rotational drive of the first transmission and the rotational drive of the second transmission.

A power transmission device according to an aspect of the present disclosure includes a first drive unit having a first drive source, a first transmission connected to the first drive source and the driving force to be transmitted, a second drive source, and a second transmission connected to the second drive source and the driving force to be transmitted, and includes a second drive unit arranged in parallel with the first drive unit, and a frictional differential limiting element disposed between the first transmission and the second transmission and limiting a differential between the rotational drive of the first transmission and the rotational drive of the second transmission.

Outer plates have a doughnut-like disk shape and are attached to the inner circumferential surface of a case member. On the other hand, inner plates have a substantially arc shape and are swingably supported about a position at a distance from the center of rotation of a shaft. The inner plates are held at a first position, at which the interlocking area between the outer plates and the inner plates is small, by a tension coil spring when the relative rotational speed between the case member and the shaft is small, and, when the relative rotational speed between the case member and the shaft exceeds a predetermined value are pivotally moved toward the outer plates by the shearing force of a viscous fluid and held at a second position at which the interlocking area between the movable plates and the first plates is large.