In front-wheel drive vehicle layouts, the engine can be mounted transversely or longitudinally. Drive is transmitted to the front wheels through a transaxle.
In a conventional rear-wheel drive layout, the engine and transmission are mounted longitudinally at the front of the vehicle and drive is transmitted to a rear axle assembly by a propeller shaft.
In a conventional four-wheel drive vehicle, propeller shafts connect a transfer case at the rear of the transmission to final drive units on both front and rear axles.
All-wheel drive systems continuously power all four wheels and provide maximum traction in all driving conditions. In a part-time system the driver manually shifts between two- and four-wheel drive, and a part-time 4WD vehicle should not be driven on dry roads when in 4WD mode.
