In an automobile

Automobile

An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

, the spindle is a part of the suspension

Suspension (vehicle)

Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose — contributing to the car's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants...

 system that carries the hub for the wheel and attaches to the upper and lower control arms. The spindle is referred to as an Upright in UK-built vehicles and in areas dominated by these cars like Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

etc.

Design

There are several considerations when designing an upright. Loads and forces need to be considered. Vertical and horizontal forces greater than those due to 5 times the acceleration of gravity, that is, over about 50 meters per second per second, are sometimes considered desirable.

Driven wheel

The forces on a driven wheel include forward and reverse propulsion as well as the braking and turning forces.