Like a full floating axle system, the drive shafts in a front-wheel drive independent suspension system do not support any vehicle weightĠ Series Shinkansen wheel used on Japanese high-speed bullet trainsĪ straight axle is a single rigid shaft connecting a wheel on the left side of the vehicle to a wheel on the right side.
The axle shafts (usually constant-velocity type) then transmit driving torque to the wheels. They may be attached to the vehicle frame or body, or integral in a transaxle. These systems still have differentials, but will not have attached axle housing tubes. This is typical of the independent suspensions found on most newer cars and SUVs, and on the front of many light trucks. In other types of suspension systems, the axles serve only to transmit driving torque to the wheels the position and angle of the wheel hubs is an independent function of the suspension system. Conversely, many front-wheel drive cars have a solid rear beam axle. 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.
The axles in this system must also bear the weight of the vehicle plus any cargo. In a live-axle suspension system, the axles serve to transmit driving torque to the wheel, as well as to maintain the position of the wheels relative to each other and to the vehicle body. This very loose definition of "axle" is often used in assessing toll roads or vehicle taxes, and is taken as a rough proxy for the overall weight-bearing capacity of a vehicle, and its potential for causing wear or damage to roadway surfaces.Īxles are an integral component of most practical wheeled vehicles. Thus, transverse pairs of wheels in an independent suspension may be called an axle in some contexts. However, in looser usage, an entire assembly including the surrounding axle housing (typically a casting) is also called an axle.Īn even broader (somewhat figurative) sense of the word refers to every pair of parallel wheels on opposite sides of a vehicle, regardless of their mechanical connection to each other and to the vehicle frame or body. Strictly speaking, a shaft which rotates with the wheel, being either bolted or splined in fixed relation to it, is called an axle or axle shaft. On cars and trucks, several senses of the word axle occur in casual usage, referring to the shaft itself, its housing, or simply any transverse pair of wheels.