Rack and pinion steering uses a gear-set to convert the circular motion of the tyre in to the linear motion necessary to turn the wheels. It also offers a gear reduction, therefore turning the wheels is easier.
It works by enclosing the rack and pinion gear-set in a steel tube, with each end of the rack sticking out from the tube and linked to an axial rod. The pinion equipment 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 attached to the spindle.
Most cars need three to four complete turns of the tyre to go from lock to lock (from far to far remaining). The steering ratio shows you how far to carefully turn the tyre for the wheels to carefully turn a certain amount. An increased ratio means you should turn the steering wheel more to carefully turn the wheels a certain amount and lower ratios give the steering a quicker response.
Some cars use variable ratio steering. This rack and pinion steering program uses a different number of tooth per cm (tooth pitch) in the centre than at the ends. The result is the steering can be more sensitive when it’s turned towards lock than when it’s close to its central placement, making the car more maneuverable.
There are two main types of rack and pinion steering systems:
End remove – the tie rods are mounted on the finish of the steering rack via the inner axial rods.
Centre take off – bolts attach the tie rods to the center of the steering rack.
As steering is vital for controlling your vehicle, it’s vital that you diagnose and repair any steering issues as quickly as possible.
The chances are your car 
has rack and pinion steering.
Thankfully, the basics aren’t hard to understand at all: it’s all about turning rotational motion into linear. When you turn the tyre, this turns a steering column, which rotates the attached steering shaft and a worm gear known as the pinion. This gear sits on the ‘rack’, a length of metal with a series of teeth cut into it. In order the pinion rotates, the rack moves either left or correct, based on your steering input.
Power steering adds a device to one aspect of the rack with a hydraulically actuated piston inside. A rotary valve directs hydraulic fluid to either the right or left part of the piston – based on the steering direction – which applies pressure on the piston and reducing your time and effort had a need to move the rack.
The rack-and-pinion gearset does two things:
It converts the rotational motion of the steering wheel into the linear motion needed to turn the wheels.
It offers a gear reduction, which makes it easier to turn the wheels.
On most cars, it takes three to four complete revolutions of the tyre to make the wheels turn from lock to lock (from far still left to far right).