Four-wheel drive (4WD) refers to vehicles with two axles providing torque to four axle ends. Braking is achieved by a disc brake mounted on the rear axle. A horizontal wheel with a vertical axle. It uses a double wishbone front axle and a 5-link rear axle. The gearbox was installed on the rear axle. The rear axle has a 3.73&colon;1 ratio. The 4500/5500 Rams rear axle is a Dana S 110. All cars have the engine located between the driver and the rear axle. Wider arches allow for a wider axle and wheels. The Estate model gets air suspension with self leveling as default on the rear axle. It consists of an axle, bearings and a hub shell. The axis of rotation fixed by the axle is common to both wheels. This arrangement allows the axle and wheels to turn horizontally. The series II had problems with its Standard Companion estate car rear axle and differential. The rear axle is now a 11.5 AAM axle (with selectable locker).