Servicing the steering System

power unit

A belt-or gear-driven pump that produces hydraulic pressure for use in the steering box or rack.

adjustable bushing

A brace or nylon part that pushes against the rack to adjust the mesh of the rack teeth to the pinion teeth.

steering damper

A device used to prevent shocks from irregular roads from being transmitted through the steering linkage and back to the steering wheel.

preloaded

A part that is already compressed from pressure.

rack

A steel rod driven by the pinion with tie-rods on each end or tie-rods connected to the center of the rack.

tie-rod

A steering component that transfers linear motion from the steering box to the steering arms at the front wheels.

antibinding

The release of something when it gets stuck.

inertia

The resistance to a change in motion.

end play

unwanted lateral movements of the worm shaft.

steering column

A column affixed between the steering wheel and the steering box, usually made to collapse during a crash.

gear ratio

A comparison of the number of turns or speed of the input (first) gear in the train to the number of turns or speed of the output (last) gear in the train.

adjustment sleeve

A component that connects the tie-rods together and to the center link on some applications, providing the adjustment point for toe-in or toe-out, depending on the manufacturer's specifications.

gear reduction

A gear ratio used to make large turns of the steering wheel into smaller turns of the tire to ease steering for the driver.

parallelogram steering system

A non-rack-and-pinion system that uses a series of parts consisting of the pitman arm, idler arm, center link, and tie-rod assemblies that relays movement from the steering gear-box to the wheel assembly.

power steering

A option on a vehicle that allows movement of the steering wheel with decreased driver effort.

engine-driven hydraulic pump

A power steering pump driven by a belt or gear off of the crankshaft.

electrically assisted steering (EAS)

A power-assist system that uses an electric motor to replace the hydraulic pump to decrease steering effort.

worm gear steering

A robust steering system frequently used on heavier vehicles that uses a worm to turn a meshed worm wheel to provide gear reduction, making steering easier for the driver

steering sensor

A sensor that can read both torque and rotation from the steering wheel.

power steering pump

A small hydraulic pump that provides assistance to the driver when turning the steering wheel.

clock spring

A special rotary electrical connector located between the steering wheel and the steering column that maintains a constant electrical connection with the wiring system while the vehicle's steering wheel is being turned.

torsion bar

A spring-loaded piece of steel connected to the pinion gear as its bottom end and the input shaft as its top. Also, a torsion bar is a type of spring that some vehicles use to hold up a corner of the vehicle.

drag link

A steel or iron rod that transfers movement of the pitman arm to a relay lever.

intermediate shaft

A steel rod positioned at an angle from the steering column to the steering gear that functions in transferring movement from one to the other.

relay lever

A steel rod that transfers movement from the drag link to an idler arm.

recirculating ball steering box

A steering box that has worm gear inside a block with a threaded hole in it and gear teeth cut into its outside that engage the sector shaft to move the pitman arm; generally used on trucks and heavy vehicles.

rack-and pinion steering system

A steering system composed of a steering wheel, a main shaft, universal joints, and an intermediate shaft. When the steering wheel is turned, movement is transferred by the main shaft and intermediate shaft to the pinion.

four-wheel steering system

A steering system in which the front wheels are controlled normally and the rear wheels use a computer and electronic motors to turn the rear linkage.

electric power steering system (EPS)

A steering system that uses an electric motor and sensors to provide feedback to the vehicle's computer systems to decrease steering effort.

electrically powered hydraulic steering (EPHS)

A steering system that uses an electric motor to produce hydraulic assist for steering.

beam axle

A suspension system in which one set of wheels is connected laterally by single beam or shaft.

active control

A system of providing constant feedback from sensors in the vehicle to the control unit.

constant mesh

A term used to describe tow or more parts, such as gears, that are in constant contact with each other.

wheel assembly

A term used to encompass all components of the wheel and tire.

flow-control valve

A valve used in power steering pumps to control the amount of flow out of the power steering pump.

control unit

Any device that controls another object such as a computer.

rubber bellows

Rubber pieces positioned on each end of the rack to protect the inner joints from dirt and contaminations and retain the grease lubricant inside the rack-and-pinion housing.

toe-setting

Setting of the toe-in or toe-out of the tires to the centerline of the vehicle.

steering linkage

Steel rods that connect the steering box to the steering arms on the steering knuckle.

actuating

The act of making something move or work.

power assist unit

The electric motor in electric power assist steering systems.

chassis

The frame of a vehicle, to which the suspension pieces attach.

inner tie-rod or socket

The inner tie-rod is attached to the end of the rack and allows for suspension movement and slight changes in steering angles.

steering knuckle

The knuckle located between the lower control arm and MacPherson strut or upper control arm, which has a spindle made or bolted onto it to which the wheel hub is attached.

rack housing

The outer shell of the rack-and-pinion steering system that is mounted to the chassis.

knuckle

The part that contains the wheel hub or spindle and attaches to the suspension components.

tie-rod assembly

The part that fits between the rack and steering arms and transfers the movement of the rack.

worm shaft

The protrusion of the worm gear that serves as the point of attachment to the steering column.

reduction ratio

The ratio between the turns of the steering wheel and the turn of the wheel, both measured in degrees.

outer tie-rod

The tie-rod attached between the tie-rod and the steering arm. It transfers the movement of the rack, pivoting as the rack is extended or retracted when the vehicle is negotiating turns.

bump steer

The undesired condition produced when hitting a bump where the vehicle darts to one side as the steering linkage is pushed or pulled as a result of the travel of the suspension.