Editing Axle (section)

==Vehicle axles==
Axles are an integral component of most practical wheeled vehicles. In a solid, "live-axle" suspension system, the rotating inner axle cores (or half-shafts) serve to transmit driving [[torque]] to the wheels at each end, while the rigid outer tube maintains the position of the wheels at fixed angles relative to the axle, and controls the angle of the axle and wheels assembly to the vehicle body. The solid axles (housings) in this system must also bear the weight of the vehicle plus any cargo. A non-driving axle, such as the front beam axle in heavy-duty trucks and some two-wheel drive light trucks and vans, will have no shaft, and serves only as a suspension and steering component. Conversely, many front-wheel drive cars have a one-piece rear beam axle.

In other types of suspension systems, the axles serve only to transmit driving torque to the wheels: the position and angle of the wheel [[Wheel#Hub|hubs]] is made independent from the axles by the function of the suspension system. This is typical of the independent suspensions found on most newer cars, and even SUVs, and on the front of many light trucks. An exception to this rule is the independent (rear) [[swing axle]] suspension, wherein the half-axles are also load-bearing suspension arms.

Independent drive-trains still need [[differential (mechanical device)|differentials]] (or diffs), but without fixed axle-housing tubes attached. The diff may be attached to the vehicle frame or body, and/or be integrated with the transmission (or gearbox) in a combined [[transaxle]] unit. The axle (half-)shafts then transmit driving torque to the wheels, usually via [[constant-velocity joint]]s. Like a full floating axle system, the drive shafts in a front-wheel-drive independent suspension system do not support any vehicle weight.