Vehicles with part-time four wheel drive are designed for optional off road use.
Four wheel drive can be selected for abnormal surfaces and disconnected for normal road surfaces.
In this application, the engine and transmission are mounted longitudinally at the front. Propeller shafts connect a transfer case, which is attached to the rear of the transmission, to final drive units on both front and rear axles.
The beam type axle housings enclose the crown wheel and pinion and differential gears, and the offset propeller shafts mean the drive is transmitted through short and long axle shafts to the driving wheels.
Steering is catered for by mounting the front wheel hubs on large ball swivels, attached to the ends of the axle housing. Universal joints are incorporated in the front axle shafts.
The transfer case lets the driver select either two-wheel-drive or four-wheel-drive in high range, or four-wheel drive in low range.
A neutral position allows an accessory, such as a cable winch, to be driven from a power take-off gear on the transmission output shaft.
When four wheel drive is engaged, the front and rear propeller shafts are locked together and driven at the same speed. Drive is transmitted to front and rear final drive units simultaneously.
