Rack and pinion steering uses a gear-established to convert the circular movement of the tyre in to the linear motion necessary to turn the wheels. It also provides a gear reduction, so turning the tires is easier.
It works by enclosing the rack and pinion gear-set in a metallic tube, with each end of the rack protruding from the tube and linked to an axial rod. The pinion gear is mounted on the steering shaft to ensure that when the steering wheel is turned, the apparatus 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 remaining). The steering ratio demonstrates how far to turn the steering wheel for the tires to turn a certain amount. An increased ratio means you need to turn the tyre more to turn the wheels a particular quantity and lower ratios supply the steering a quicker response.
Some cars use adjustable ratio steering. This rack and pinion steering system runs on the different number of the teeth per cm (tooth pitch) in the centre than at the ends. The effect is the steering is more sensitive when it is turned towards lock than when it is close to its central placement, making the car more maneuverable.
There are two main types of rack and pinion steering systems:
End take off – the tie rods are attached to the finish 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 vehicle, it’s important to diagnose and repair any steering issues as quickly as possible.
The chances are your vehicle has rack and pinion steering.
Thankfully, the fundamentals aren’t hard to understand at all: it’s about turning rotational motion into linear. When you convert the tyre, 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 amount of metal with some teeth cut involved with it. In order the pinion rotates, the rack movements either left or correct, depending on your steering input.
Power steering provides a device to one side of the rack with a hydraulically actuated piston 
inside. A rotary valve directs hydraulic liquid to either the proper or left side of the piston – based on the steering path – which applies pressure 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 motion of the tyre into the linear motion needed to turn the wheels.
It offers a gear reduction, which makes it simpler to turn the wheels.
On most cars, it takes three to four complete revolutions of the tyre to help make the wheels turn from lock to lock (from far still left to far right).