300px, Double Wishbone Suspension In automotive suspension, a steering knuckle or upright is that part which contains the

wheel hub A wheel is a circular component that is intended to rotate on an axle bearing. The wheel is one of the key components of the wheel and axle which is one of the six simple machines. Wheels, in conjunction with axles, allow heavy objects to be ...

spindle Spindle may refer to: Textiles and manufacturing * Spindle (textiles), a straight spike to spin fibers into yarn * Spindle (tool), a rotating axis of a machine tool Biology * Common spindle and other species of shrubs and trees in genus '' Euony ...

, and attaches to the suspension and steering components. The terms ''spindle'' and ''hub'' are sometimes used interchangeably with steering knuckle, but refer to different parts. The wheel and tire assembly attach to the hub or spindle of the knuckle where the tire/wheel rotates while being held in a stable plane of motion by the knuckle/suspension assembly. In the attached photograph of a double-wishbone suspension, the knuckle is shown attached to the upper control arm at the top and the lower control arm at the bottom. The wheel assembly is shown attached to the knuckle at its center point. Note the arm of the knuckle that sticks out, to which the steering mechanism attaches to turn the knuckle and wheel assembly.

Types

Steering knuckles come in all shapes and sizes. Their designs differ to fit all sorts of applications and suspension types. However, they can be divided into two main types. One comes with a hub and the other comes with a

.{{Cite news, url=https://www.roadandtrack.com/car-culture/car-accessories/reviews/a4258/boot-what-the-knuckle/, title=What the #&@% is it?, date=2013-04-15, work=Road & Track, access-date=2018-05-03, language=en-US

Applications

In a non-drive suspension, as shown in the first photo, the knuckle usually has a spindle onto which the brake drum or brake rotor attaches. (In this picture, the central spindle upon which the wheel assembly rides cannot be seen.) The wheel/tire assembly then attaches to the supplied lug studs, and the whole

assembly Assembly may refer to: Organisations and meetings * Deliberative assembly, a gathering of members who use parliamentary procedure for making decisions * General assembly, an official meeting of the members of an organization or of their representa ...

rotates freely on the shaft of the spindle. In a drive suspension, the knuckle has no spindle, but rather has a hub into which is affixed the bearings and shaft of the drive mechanism. The end of the drive mechanism would then have the necessary mounting studs for the wheel/tire and/or brake assembly. Therefore, the wheel assembly would rotate as the drive shaft (or

half-shaft An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing ...

) dictates. It would not turn freely by itself, but only if the shaft was disengaged from the

transaxle A transaxle is a single mechanical device which combines the functions of an automobile's transmission, axle, and differential into one integrated assembly. It can be produced in both manual and automatic versions. Engine and drive at the s ...

or differential. A driven suspension as described may also be steerable. This is often called a drive/steer arrangement. Steering_knuckle_diagram

References

Automotive steering technologies Automotive suspension technologies

Types

Applications

See also

References