Abstract: In a four-wheel drive vehicle, a rear differential includes an input shaft to which a driving force is transmitted from front wheels through a propeller shaft, a driven bevel gear mounted on the input shaft, a follower bevel gear mounted on a clutch drive shaft and meshed with the driven bevel gear, left and right electromagnetic clutches disposed between opposite ends of the clutch drive shaft and left and right output shafts. The maximum transmitted torque transmitted through the left and right electromagnetic clutches is controlled, so that it is decreased with an increase in vehicle speed detected by vehicle speed detecting means. Thus, the vehicle can avoid the maximum horsepower transmitted by the bevel gears and the electromagnetic clutches being increased with an increase in vehicle speed. Therefore, it is possible to ensure the durability of the bevel gears and the clutches, while providing a reduction in size of the bevel gears and the clutches.

Abstract: A power transmitting system having an input shaft, a driven bevel gear, a follower bevel gear and a clutch drive shaft accommodated in longitudinally bisected center casings. Left and right electromagnetic clutches connected to the clutch drive shaft are accommodated in left and right side casings which are connected to the center casings and, such that a driving force from the input shaft is transmitted to left and right wheels through the pair of bevel gears and the left and right clutches. Thus, maintenance of the clutches can be easily performed, and the check and regulation of the meshed states of the bevel gears can be easily performed.

Abstract: A power transmitting system having an input shaft, a driven bevel gear, a follower bevel gear and a clutch drive shaft accommodated in center casings. Left and right electromagnetic clutches connected to the clutch drive shaft are accommodated in left and right side casings. Oil for lubricating the electromagnetic clutches is supplied from an oil pump accommodated in the center casings and driven by the clutch drive shaft through oil passages and axially defied in the clutch drive shaft and left and right output shafts. Thus, the length of the oil passages for supplying the oil from the oil pump to the clutches can be minimized to provide a reduction in size of the power transmitting system.

Abstract: In a power transmitting system, a clutch drive shaft driven through bevel gears and by an input shaft is laterally extensive and left and right electromagnetic clutches are disposed between opposite ends of the clutch drive shaft and left and right output shafts, respectively. A clutch body heated during the transmission of a power is disposed at a laterally outer location of the system to provide enhanced heat-radiatability, and an annular solenoid is disposed inside the clutch body. A bearing for supporting each of the opposite ends of the clutch drive shaft is disposed radially inside the solenoid. Thus, the lateral dimension of the power transmitting system is reduced.

Abstract: A solenoid of an electromagnetic clutch includes an annular coil, an annular coil housing which covers a radially facing outer peripheral surface, a radially facing inner peripheral surface and an axially facing end face of the coil. An armature is adapted to be attracted to the one end face of the coil housing by supplying an electric current to the coil. The housing axially protrudes past the other axially facing end face of the coil by a distance L. Thus, the magnetic resistance around the outer periphery of the coil is decreased to enhance the magnetic flux density of the magnetic closed circuit, thereby enabling the reliable attraction of the armature without increasing the electric power consumed by the coil.