Axles are structural components that link the opposing wheels of a vehicle. In addition, the brakes and suspension of the vehicle are attached to the axle. Centrally located and connected to a bearing or spindle, the axle is responsible for rotating the wheels or gears of the vehicle and causing it to move.
Axles are kept in place by a bearing that is located inside the hole of the wheel or gear, a factor largely responsible for the axle’s ability to rotate the wheel, resulting in the movement of a vehicle. However, the wheel or gear can also be permanently fixed to the axle with the bearing, also known as a spindle, to act as a support.
The axle has many responsibilities within a vehicle. Not only does it allow a wheel or gear to rotate, but it also must bear the weight of the vehicle, as most car and equipment wheels are the only part touching the ground. The axle is a prime component that makes up the drivetrain, a device that works with the motor and transfers power to the wheels. Just as the axle allows the wheels to rotate, it also controls the brakes when the braking mechanism is applied. The steering mechanism of some vehicles are operated by steering axles located at the front of the vehicle. This axle works primarily with the front wheels to steer them in the desired direction.
Different configurations are constructed for certain types of vehicles. The basic type of axle is the single axle. Other types include drive, airlift, and dead axles.
Drive axles are found on vehicles that are driven by the engine. The combination of transmission and axle gives way to the term transaxle, which is commonly used for this configuration. This is normally found on modern vehicles and is the result of the axle dividing between the differential and the universal joint to allow the wheels to move forward as well as pivot.
Airlift axles are unique to articulated dump trucks, giving them the ability to raise and lower the axle. This type allows the axle to be lowered when the weight capacity needs to be increased or the weight of the cargo needs to be evenly distributed.
Dead axles are free-rotating axles located at the rear of a front-wheel drive car.