PURPOSE: To enhance maneuverability, start acceleration and durability by furnishing an oil-hydraulic clutch, which is operated by the line pressure for the speed changer, in a transfer clutch of the four-wheel drive device equipped with an automatic speed changer etc. and thereby making it possible to change over from FF to 4WD and vice versa.
CONSTITUTION: A transfer mechanism 6 for four-wheel drive is coupled with an extension case 30 at its rear and is provided with a rear drive shaft 31 rotatably inside the case 30. The shaft 31 is fitted with a transfer clutch 35 in oil-hydraulic clutch type in the same manner as the automatic speed changer 3, and a drum 35a is coupled with the shaft 31 in a solid body for its hub 35b to transmit the power to the transfer drive shaft 33. When, in the case of high load run, the line pressure is fed to the clutch 35 from the oil-hydraulic control device 5 to put the drum 35a in engagement with the hub 35b, the transfer gear 34 is directly coupled with the drive shaft 31 to transmit the power from the shaft 31 to the rear wheels through the propeller shaft 37. Thus the four-wheel drive condition is obtained.
KOBAYASHI TOSHIO