A control system for a 4-wheel drive transmission including a main transmission and an auxiliary transmission shiftable by operation of a hydraulic clutch for switching the mode of operation either to 2-wheel drive or 4-wheel drive including a manual changeover valve mechanically connected to a shift lever in a passenger's room of a vehicle for operating the hydraulic clutch according to the mode selected by the shift lever.
A transfer in combination with a transmission mechanism for a four wheel drive vehicle is provided comprising a first output shaft aligned with the transmission mechanism, a second output shaft extending parallel to the first output shaft, a power transmission mechanism for transmitting driving force from the first to the second output shaft, and a clutch coaxially mounted on the second output shaft for connecting and disconnecting the second output shaft to and from the power transmission mechanism. In addition to the clutch between the second output shaft and the power transmission mechanism, another clutch may be provided between the first output shaft and the power transmission mechanism. The transmission/transfer further includes parking locks for stopping the rotation of the first and second output shafts. A control apparatus is associated with the clutches between the first and second output shafts and the power transmission mechanism and includes a delay unit for providing a time lag between the engagements of the clutches.
A simple planetary gear arrangement is provided for a transfer case. The transfer case includes a carrier connected to the transfer case input. The ring gear is connected with a rear axle. The sun gear is connectable with a front axle through a clutching arrangement including a one-way clutch and a dog clutch in parallel. The one-way clutch and the dog clutch are independently engageable. The sun gear is selectively groundable through a friction clutch. Accordingly, the simple planetary gear set functions as a gear ratio producing device when the friction clutch is engaged, and as a center differential when the dog clutch or one-way clutch is engaged.