Steering

The Principles of Steering

The basic aim of steering is to ensure that the wheels are pointing in the desired directions. This is typically achieved by a series of linkages, rods, pivots and gears. One of the fundamental concepts is that of caster angle – each wheel is steered with a pivot point ahead of the wheel; this makes the steering tend to be self-centering towards the direction of travel.The steering linkages connecting the steering box and the wheels usually conform to a variation of Ackermann steering geometry, to account for the fact that in a turn, the inner wheel is actually travelling a path of smaller radius than the outer wheel, so that the degree of toe suitable for driving in a straight path is not suitable for turns. The angle the wheels make with the vertical plane also influences steering dynamics (see camber angle) as do the tires.

steering ball joint

Ackermans Principle, TOOT - Toe Out On Turns

The Ackerman Steering principle is a geometric arrangement of linkages in the steering of a car or other vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out circles of different radii.

By inclining the track arms towards the centre of the rear axle, when turning, both front wheels turn around a common theoretical point, maintaining true rolling motion and minimising tyre scrub.

Ackermann steering principle

By Ackermann.svg: User:Bromsklossderivative work: Andy Dingley (talk) - Ackermann.svg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11038290

Toe-in and Toe-out, Wheel alignment - How it works.

How the wheel alignment and relative toe setting affects a cars handling and tyre wear.

Making sure your wheel alignment is correct can reduce uneven tyre wear, improve the handling of your vehicle and save you money by lowering fuel consumption.

Rack and Pinion Steering

A look at rack and pinion steering as fitted to most cars.

Most modern cars use rack and pinion steering mechanisms, where the steering wheel turns a pinion gear; and the pinion moves the rack, which is a linear gear that meshes with the pinion. This movement converts the rotary (circular) motion of the steering wheel into a linear motion along the transverse axis of the car (side to side motion). This motion applies steering torque to the swivel pins / kingpins of the stub axle of the steered wheels via tie rods and a steering arm.The rack and pinion design has the advantages of a large degree of feedback and direct steering "feel". A disadvantage is that it is not adjustable, so that when it does wear and develop backlash, in some racks this can be rectified by replacing a nylon insert, other than this, the only cure is replacement of the steering rack.

Power Assisted Steering - How it Works

A look at how power assisted steering (sometimes called power steering) works on a car.

Power assisted steering is fitted to vehicles and allows the driver to overcome the high steering resistance due to heavy loads or wider tyres, with minimum effort.

PAS means that we don't need to provide such a deep reduction inside the steering box/rack, this in turn means that we can have less turns lock-to-lock of the steering wheel.

PAS power assisted steering reservoir