Steering columns
|
A flexible joint connects the steering column to the input shaft of the steering box. It allows alignment of the steering column with the steering box.
|
Rack-and-pinion gearbox
|
The rack-and-pinion steering box has a pinion, connected to the steering column. This pinion runs in mesh with a rack that is connected to the steering tie rods.
|
Helix
|
The helix shape is commonly used as a thread on nuts and bolts, and also for teeth in steering gears, and transmissions.
|
Variable ratio steering
|
With variable ratio steering, as the steering moves away from the straight-ahead position, the ratio, and therefore, the mechanical advantage, increases progressively.
|
Worm gearbox
|
Variations of worm-type steering boxes are worm-and-sector, worm-and-roller, worm-and-nut, and recirculating ball. The steering box gear ratio increases output torque, reducing the effort the driver must apply.
|
Power steering
|
Power steering systems produce assistance that reduces the driver’s effort. They are of most benefit during slow cornering and when parking.
|
Steering process
|
When a load is applied to the steering system, the torsion bar twists, causing relative movement of the inner and outer members of the rotary valve. Assistance progressively rises as the torsion bar twist increases.
|
Flow-control valve
|
Power steering pumps have a flow-control valve to vary fluid flow and system pressures. A pressure relief valve prevents excessive pressures developing when the steering is on full-lock.
|
Electric power assisted steering
|
Electric steering is more economical to run, and easier to package and install than conventional hydraulic power steering systems. They are also lighter and more compact than conventional hydraulic systems.
|
| Basic electric power steering operation |
The microprocessor control unit analyzes inputs from the steering sensor as well as the vehicle’s speed sensor. The sensor inputs are then compared to determine how much power assist is required. |
