rack and pinion

Rack and pinion steering uses a gear-established to convert the circular motion of the steering wheel into the linear motion required 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 metallic 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 apparatus spins, shifting the rack. The axial rod at each end of the rack links to the tie rod end, which is attached to the spindle.
Most cars need three to four complete turns of the steering wheel to move from lock to lock (from far right to far still left). The steering ratio demonstrates how far to turn the steering wheel for the tires to carefully turn a certain amount. A higher ratio means you need to turn the tyre more to 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 program uses a different number of teeth per cm (tooth pitch) at the heart than at the ends. The result is the steering is definitely more sensitive when it is turned towards lock than when it's near to its central rack and pinion china position, making the automobile more maneuverable.
There are two main types of rack and pinion steering systems:
End remove – 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 center of the steering rack.
As steering is essential for controlling your car, it's important to diagnose and repair any steering problems as quickly as possible.
The chances are your car 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 switch the tyre, this turns a steering column, which rotates the attached steering shaft and a worm equipment known as the pinion. This gear sits on the ‘rack', a amount of metal with some teeth cut involved with it. So as the pinion rotates, the rack movements either left or right, 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 proper or left part of the piston – depending on the steering direction – which applies pressure 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 tyre in to the linear motion needed to turn the wheels.
It provides a gear reduction, which makes it easier to turn the wheels.
On most cars, it takes 3 to 4 complete revolutions of the steering wheel to make the wheels turn from lock to lock (from far still left to far right).