Power Steering is a feature that uses an alternate power source to rotate the steering along with the efforts of the
driver making it easier to operate especially at low speeds.
The reason for power assisted steering is to ease the physical effort required to turn the steering as the steering
has a direct connection to the front wheels.
The weight of the vehicle presses down on all four wheels but the engines and
transmissions in most vehicles are mounted at the front so that puts extra
weight on the front wheels.
While power assisted steering makes driving a lot more comfortable for the driver a serious benefit is that it
increases the performance of the vehicle.
It does not increase the speed of the vehicle but it allows the driver to corner the vehicle at higher speeds more
confidently. The driver can easily perform manoeuvres and it greatly increases the fun to drive factor.
There are three types of power steering and each type can affect how the vehicle performs;
Most steering systems use the rack and pinion mechanism. The rack is the steering rack where the end opposite to the
steering wheel has threads like a large screw. The pinion is the shaft that is connected to both wheels, it has grooves in it
and the threads from the rack fit in these grooves.
- Hydraulic - A hydraulic pump usually driven by a belt from the engine to store pressure. This pressure is then
applied to the steering in the direction the driver is turning it.
- Electro-Hydraulic - A hydraulic pump is also used but it is driven by an electric motor which is controlled by
an ECU. The motor is usually close to the hydraulic pump.
- Electric - An electric motor also controlled by an ECU is attached to the steering rack. The motor is used to
directly apply power as the steering rack rotates.
As the steering wheel and rack rotates the threads pulls on the grooves in the pinion and it moves the wheels in the
The power assistance is an addition to the steering mechanism and should never be a direct part of the mechanism
because the driver should be able to steer the vehicle without the power assistance. Such a situation would make the vehicle
difficult to manoeuvre but it will be fail safe.
Power steering should also allow the driver to still feel a connection to the ground through the steering. This makes
too much assistance a bad thing as it can make the steering feel numb.