Rack and pinion steering uses a gear-arranged to convert the circular motion of the steering wheel in to the linear motion necessary to turn the wheels. It also offers a gear reduction, therefore turning the wheels is easier.
It functions by enclosing the rack and pinion gear-set in a steel tube, with each end of the rack protruding from the tube and connected to an axial rod. The pinion gear is attached to the steering shaft to ensure that when the steering wheel is turned, the gear spins, shifting the rack. The axial rod at each end of the rack connects to the tie rod end, which is mounted on the spindle.
Most cars need 3 to 4 complete turns of the tyre to move from lock to lock (from far to far left). The steering ratio demonstrates how far to carefully turn the tyre for the tires to carefully turn a certain amount. An increased ratio means you need to turn the tyre more 
to carefully turn the wheels a specific quantity and lower ratios give the steering a quicker response.
Some cars use variable ratio steering. This rack and pinion steering system uses a different number of tooth per cm (tooth pitch) in the centre than at the ends. The effect is the steering is more sensitive when it’s switched towards lock than when it’s close to its central position, making the car more maneuverable.
There are two main types of rack and pinion steering systems:
End take off – the tie rods are mounted on the finish of the steering rack via the inner axial rods.
Centre remove – bolts attach the tie rods to the center of the steering rack.
As steering is essential for controlling your car, it’s vital that you diagnose and repair any steering issues as fast as possible.
The chances are your vehicle has rack and pinion steering.
Thankfully, the basics aren’t hard to grasp at all: it’s all about turning rotational motion into linear. When you convert the steering wheel, this turns a steering column, which rotates the attached steering shaft and a worm equipment referred to as the pinion. This gear sits on the ‘rack’, a length of metal with a series of teeth cut into it. So as the pinion rotates, the rack techniques either left or right, depending on your steering input.
Power steering adds a device to 1 part of the rack with a hydraulically actuated piston inside. A rotary valve directs hydraulic liquid to either the right or left aspect of the piston – based on the steering path – which applies strain on the piston and reducing the effort needed to move the rack.
The rack-and-pinion gearset does a couple of things:
It converts the rotational movement of the steering wheel in to the linear motion had a need to turn the wheels.
It provides a gear reduction, which makes it simpler to turn the wheels.
On many cars, it takes 3 to 4 complete revolutions of the tyre to help make the wheels turn from lock to lock (from far left to far right).
