Abstract: A propeller shaft comprises two torque transmission members, a viscous fluid damper and a torsion bar which are arranged in parallel between the torque transmission members, and a stopper for restricting the maximum torsion angle of the torsion bar. Thus, torsional vibration characteristic is adjusted in a wide range. Accordingly, a vibration a and noise in a power transmission system can be prevented, and also, a starting acceleration performance of a vehicle can be improved.

Abstract: Arranged within a differential gear case are first and second side gears rotating together with first and second output shafts, respectively; first and second differential gears engaged with one of the first and second side gears and rotatably supported within cylindrical holes, respectively, so as to be partially engaged with each other to move circularly together with the differential gear case; and a viscous coupling capable of transmitting, between a hub rotating together with the output shaft and a housing, a torque in response to the difference in the speed. The outer periphery of the housing is provided with a cam surface to be engaged, in the direction of rotation, with the first and second differential gears to press and bias the first and second differential gears against the inner cylindrical surfaces of the cylindrical holes.

Abstract: In a differential gear apparatus provided with a differential limitation mechanism, to prevent a washer interposed between the differential case and the coupling case from being seized by heat when viscous fluid is sheared into high temperature and pressure, the coupling case is formed integral with a first output shaft to increase rigidity of the coupling case. Further, it is preferable to form an inner hub integral with a second output shaft to increase rigidity of the inner hub.

Abstract: A viscous coupling capable of preventing decrease in torque obtained by the shear force. The viscous coupling includes relatively rotatable first, second, and third rotating members forming an operation chamber in which a viscous fluid is to be confined; a dividing member placed inside the operation chamber for dividing the operation chamber into a first chamber formed by the dividing member and the first and third rotating members, and a second chamber formed by the dividing member and the second and third rotating members; and a pump for controlling flow of the viscous fluid between the first and second chambers.