Front Axle

a set of subassemblies or a separate chassis assembly on self-propelled wheeled vehicles (automobiles, tractors) that connects the front part of the frame or load-carrying body to the front wheels. The design of a front axle depends on the type of suspension. With conventional spring suspension, the front axle is a rigid unsprung beam to which the wheel hubs are attached by means of steering knuckles and kingpins. With independent suspension the front axle is replaced by a load-carrying transverse frame member to which hinged rocker arms are attached.

On four-wheel-drive vehicles the front axle is powered as well as the rear axle. In this type of construction the load-carrying beam of the front axle is rigidly joined to the transmission housing. Short semiaxles are connected to the wheels by means of special constant-velocity joints. On rough terrain, the front axle can be connected through a transfer case with a separate shift lever.