Abstract: A four wheel drive torque transfer mechanism with a hydraulic control system is switchable between two wheel drive and four wheel drive during running of a vehicle having an automatic transmission. A reducer permits direct coupling or reduced speed ratio drives. A parking gear associating with the transfer device requires only small modification to the conventional parking mechanism. The hydraulic control system automatically actuates the reducer to provide a reduced speed-high torque output when a governor output responsive to vehicle speed, falls below a predetermined level.

Abstract: A transmission for four-wheel drive vehicles of the type having a four-wheel drive transfer disposed between the front transmission section having a gear train or a planetary gear train therein and the rear transmission section to which lubricating oil or hydraulic operating fluid is to be introduced, the improvement comprising a wet type or multi-plate clutch for the four-wheel drive transfer which permits a smooth switching over between a two-wheel drive mode and a four-wheel drive mode while the vehicle is cruising, and further comprising a fluid path which connects between the bottom of the rear transmission section and the front transmission section and through which the lubricating oil or hydraulic operating oil in the rear transmission section can be smoothly returned to the oil pan located under the rear transmission section.