Rack and pinion steering runs on the gear-arranged to convert the circular movement of the steering wheel into the linear motion necessary to turn the wheels. It also provides a gear reduction, so turning the tires 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 linked to an axial rod. The pinion gear is attached to the 
steering shaft so that when the steering wheel is turned, the gear spins, moving 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 proceed from lock to lock (from far right to far remaining). The steering ratio shows you how far to carefully turn the steering wheel for the tires to turn a certain amount. An increased ratio means you should turn the tyre more to 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 runs on the different number of the teeth per cm (tooth pitch) in the centre than at the ends. The effect is the steering can be more sensitive when it is turned towards lock than when it is 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 attached to 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 essential for controlling your car, it’s important to diagnose and restoration any steering issues as quickly as possible.
The chances are your vehicle has rack and pinion steering.
Thankfully, the fundamentals aren’t hard to grasp at all: it’s 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 known as the pinion. This equipment sits on the ‘rack’, a amount of metal with a series of teeth cut into it. So as the pinion rotates, the rack moves either left or right, 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 liquid to either the proper or left aspect of the piston – based on the steering direction – which applies strain 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 movement of the steering wheel into the linear motion needed to turn the wheels.
It offers a gear reduction, which makes it simpler 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 still left to far right).
