Rack and pinion steering runs on the gear-established to convert the circular motion of the tyre in to the linear motion required to turn the wheels. It also offers a gear reduction, so turning the tires is easier.
It functions by enclosing the rack and pinion gear-set in a metal tube, with each end of the rack sticking out from the tube and connected to an axial rod. The pinion gear is attached to the steering shaft so that when the tyre 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 three to four complete turns of the tyre to proceed from lock to lock (from far right to far left). The steering ratio shows you how far to turn the tyre for the tires to turn a certain amount. A higher ratio means you have to turn the tyre more to carefully turn the wheels a particular amount and lower ratios give the steering a quicker response.
Some cars use variable ratio steering. This rack and pinion steering program runs on the different number of tooth per cm (tooth pitch) in the centre than at the ends. The result is the steering is more sensitive when it is turned towards lock than when it’s near to its central position, 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 end of the steering rack via the inner axial rods.
Centre take off – bolts attach the tie rods to the centre of the steering rack.
As steering is vital for controlling your car, it’s vital that you diagnose and restoration any steering problems as quickly as possible.
The chances are your vehicle has rack and pinion steering.
Thankfully, the basics aren’t hard to grasp at all: it’s about turning rotational motion into linear. When you change the steering wheel, this turns a steering column, which rotates the attached steering shaft and a worm gear known as the pinion. This equipment sits on the ‘rack’, a amount of metal with a series of teeth cut involved with it. In order the pinion rotates, the rack techniques either left or correct, depending on your steering input.
Power 
steering provides a device to one part of the rack with a hydraulically actuated piston inside. A rotary valve directs hydraulic fluid to either the right or left aspect of the piston – depending on the steering direction – which applies strain on the piston and reducing the effort had a need to move the rack.
The rack-and-pinion gearset does a couple of things:
It converts the rotational movement of the tyre in to the linear motion had a need to turn the wheels.
It offers a gear reduction, which makes it easier to turn the wheels.
On the majority of cars, it takes three to four complete revolutions of the steering wheel to make the wheels turn from lock to lock (from far left to far right).