Axle

An axle is a rod or shaft that supports rotating wheels or gears. Depending on its design, it may remain stationary or rotate and transmit torque.

Live axle: An axle that rotates with its wheels and transmits torque to them. It combines wheel support and power transmission in a single rotating assembly.
Wheel: A circular component that rotates around an axis to support or move a load. The axle supports the wheel or provides the axis around which it turns.
Automobile: A road vehicle, usually with four wheels, powered by an engine or electric motor. Automobiles use axles to support wheels and, in driven designs, deliver torque.
Spindle (mechanical): A short shaft or pin that supports a rotating component, often a wheel or tool. A spindle is often a local wheel support, unlike a vehicle axle spanning or linking wheels.
Dead axle: A nonrotating axle that supports wheels but does not transmit driving torque. It illustrates the support-only role an axle can serve.
Shaft (mechanical engineering): A rotating machine element that transmits torque and power between components. An axle is a shaft-like component, though some axles do not rotate.
Railway axle: An axle that connects and supports the wheels of a railway wheelset. Railway axles carry heavy loads while keeping paired wheels aligned.
Drive shaft: A rotating shaft that transmits torque between separated parts of a machine or vehicle. A drive shaft delivers power to an axle but is not itself the wheel-supporting axle.
Differential: A gear mechanism that splits input torque between driven wheels while allowing them to rotate at different speeds. It connects a vehicle’s drive shaft to axle shafts and accommodates turns.
Hub: The central part of a wheel or gear that connects it to a shaft or axle. A hub forms the wheel’s connection to the axle.

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