A steering rack is an up to date version of the steering gearbox that was popularly used in older models of motor vehicle. This rack, through its co-ordination with the pinion, interprets the directional input from the steering wheel and uses it to either pull or push the vehicle’s front wheels into the driver’s desired direction. In simple terms, the steering rack is responsible for converting the steering wheel's rotational movement into linear movement in order to turn the vehicle’s wheels.
Although manual steering racks are effective, even greater steering assistance can be provided by a power steering rack. The power steering rack is of a similar construction to the manual version but, to accommodate the hydraulic power assisted steering system there is one important modification. To help drive the power assisted steering it is necessary to deliver hydraulic fluid, under pressure, to the power steering rack. This is achieved by part of the power steering rack being connected to a cylinder which has a piston in the centre. There is a fluid port on each side of the cylinder. The hydraulic fluid is sent to either side of the piston, which causes the power steering rack to move in accordance with the driver’s operation of the steering wheel, producing the power assisted steering.
A fault in the power steering rack will result in the steering becoming more difficult and will require early investigation.