What causes wheel self centering action in a vehicle?

When you turn the steering wheel to direct the front wheels, the wheels pivot about an axis that is far away from being vertical. When you let go of the steering wheel, the weight of the car pulls the steering back to its original position. This makes clear why steering wheel returns to center after turn.

What does steering axis inclination do?

Steering axis inclination (SAI) causes both front wheels to gain positive camber as they steer away from center. This acts with caster to provide self-centering of the front wheels. This gives the car straight line stability.

Why is my steering wheel crooked after an alignment?

We here at Oxford Auto & Tire can answer that question quickly and easily: Your steering wheel is off-center when you’re driving straight because your wheels aren’t aligned correctly. This is one sign of a bad wheel alignment, and you might notice the steering wheel is crooked right after you’ve had the wheels aligned.

What is the center of a steering wheel called?

Traditionally located on the steering wheel hub or center pad, the horn switch was sometimes placed on the spokes or activated via a decorative horn ring which obviated the necessity to move a hand away from the rim.

What is steering angle inclination?

4.5. The steering axis inclination, θ, is defined as the angle measured in the front elevation between the steering axis (sometimes referred to as the ‘kingpin’ axis from the days when a physical pin was used within a beam axle assembly) and the vertical.

What is kingpin inclination?

Swivel pin or kingpin inclination is the lateral inward tilt (inclination) from the top between the upper and lower swivel ball joints or the kingpin to the vertical (Figure 10.3).

What can steering axis inclination and included angle cause?

Steering Axis Inclination (SAI) This angle, when added to the camber to form the included angle (see below) causes the vehicle to lift slightly when you turn the wheel away from a straight ahead position.

What is the steering axis inclination line?

The steering axis inclination (SAI) is the angle between the centerline of the steering axis and vertical line from center contact area of the tire (as viewed from the front).

Does an alignment center the steering wheel?

The centering of the steering wheel is part of the alignment. Technically BMW is correct, the car may be within factory alignment numbers since centering the wheel simply means lengthening one sides tie rods, and shortening the other sides by exactly the same amount.

Why does a steering wheel have a self centering action?

The mechanics of how this is produced has been well explained In other answers, but the reason for having a self centering action is that it provides feedback to the driver. Without the castor self cantering effect the steering would feel lifeless, and completely neutral.

How does the steering axis inclination angle affect the steering?

There is an increase in the steering moment at the steering wheel. Regardless of which way the front wheels are turned, the larger the Steering Axis Inclination angle is, the more the car will be raised. Without any caster, this effect is symmetrical from side to side. The raise of the car has a self-aligning effect of the steering at low speeds.

What is the caster angle of a car?

The caster angle is the inclination or “rake” of the axis of rotation front suspension/steering (the axis about which the front wheels turns left or right) when viewed from the side. In modern cars, this axis is defined as a line between the upper and lower ball joints.

What happens when you turn the front wheels to steer?

Turning the front wheels to steer the car causes them to pivot about an axis which is not quite vertical, in fact the pivot axis leans “backwards” at the top of the wheel with respect to the bottom. This in turn means that turning the wheels lifts the car up very slightly and it’s your steering wheel input that holds it there.