Automotive Glossary

Automotive Glossary

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The tendency of a vehicle to drift away from the steered course when being driven. Usually associated with low or uneven tyre pressures or tight steering joints.

Wankel Engine

Rotary engine using a three-cornered rotor in a trochoidal chamber. Invented by Felix Wankel.


Twisting or bending distortion.


The legal rights given by manufacturers to cover possible defects occurring during a specified time or mileage.

Wash Primer

A primer that forms an anti-corrosive chemical film when applied on a bare metal surface. More commonly known as etching or self-etch primer.


Flat circular plate with a hole in it. Used to spread the load of a nut or bolt.

Waste Gate

Control valve in the exhaust gas flow through a turbocharger.

Water Jacket

Part of the cylinder block and head of an engine that encloses the cavity through which cooling water flows.

Water Pump

(1) Pump that circulates the water of an engine's cooling system. Also circulating pump. (2) Any pump for delivering water under pressure, as for screen washing, etc.

Water Spotting

A condition caused by water droplets evaporating on a finish before it has thoroughly dried or cured, which results in a dulling of the gloss in localised spots.

Water Trap

A bowl used to separate water from fuel.


A type of paint which uses water as its primary carrier rather than typical organic solvents.


Unit of power. Volts X amps.


The power rating of an electrical device.

Wave Wound

A winding that is wound in waves instead of individual coils.


Pattern displayed on an oscilloscope screen.


The distance between corresponding points of two consecutive waves.


A uniquely formulated blend that protects and produces a durable, high-gloss finish on a painted surface. The application of waxes make it easier to clean painted surfaces. Some also serve as polishes due to containing a percentage of very fine abrasive and are capable of removing minor paint imperfections.

Wax Injection

Anti-corrosion body wax injected into box sections.

Wax Pellet Actuator

A switch or valve that operates as temperature affects a wax pellet.

Wax Plugging

Formation of wax in diesel fuel at low temperatures that plugs the diesel fuel line or filter element preventing fuel flow.


Separation of wax in diesel fuel at low temperatures.


A thermostat operated by wax. As wax changes state from solid to liquid, its volume changes.


The change in a paint film due to exposure to natural forces, such as sunlight, rain, dust and wind.


A device used by paint manufacturers to simulate the effects of weathering. Painted samples are subjected to simulated conditions of sunlight, rain, wind and even salt spray, to test their weathering durability

Web Browser

A software package that allows you to view pages from the World Wide Web. Examples are Internet Explorer and Netscape.

Web Page

A document, usually written in HTML (Hypertext Markup Language), that can be accessed on the Internet.

Web Site

A collection of electronic 'pages'.


Description of the material used for seat belt straps.


A method of increasing force by use of a taper or inclined plane.

Weight Solids

The percentage on a weight basis, of non-volatile (i.e. the ingredients that will not evaporate) material in a paint.

Weight Transfer

The shift of a vehicle's weight towards the front when braking and towards the rear during rapid acceleration.

Welch Plug

A dished steel disc used as a core plug in engines and cylinder heads.

Wet Clutch

A friction clutch that runs in an oil bath.

Wet Film Gauge

A device used to determine wet film thickness of paint immediately after application. This is obviously a type of destructive test, as the paint surface is damaged by the gauge.

Wet Liner

Not strictly a liner as it does not line a cylinder, but is the cylinder of a water cooled engine that fits into the cylinder block in contact with the coolant.

Wet Sanding

A technique involving the sanding of a surface while it is being flushed with water. This aids with the smoothing out of surface defects before subsequent coats are applied.

Wet Spots

Discolouration caused where the paint fails to dry and adhere uniformly.

Wet Sump (Oil Pan)

An engine lubrication system where the reservoir of lubricating oil is held in a sump below the engine. As distinct from a dry sump where the reservoir of lubricating oil is kept in a separate tank.

Wet-on-Wet Application

A painting method by which a second coat of paint is applied over the first before it hardens and dries. Special primers have been developed which allow for colour to be applied on top of them with little or no flash-off time


The process by which a liquid forms intimate contact with the substrate to which it is applied.

Wheel Alignment

The relative angle of the road wheels to the true longitudinal axis of the vehicle. The toe angle is the degree of variation needed to bring the wheels into true rolling motion when the vehicle is travelling. Also known as 'toe'.

Wheel Base

The dimension from the centre of the front axle to the centre of the rear axle(s).

Wheel Bearing

Roller or ball bearing used to support a drive shaft or a wheel on a stub axle.

Wheel Cylinder

A brake hydraulic cylinder in a drum brake. It is fitted to the back plate on the wheel axle assembly.

Wheel Hub

The centre assembly of a wheel containing the wheel bearings.

Wheel Nave

Connects the rim to the wheel hub.

Wheel Offset

The distance from the wheel nave to the centre line of the wheel. Used to accommodate the brake assembly and bring the centre line of the wheel into close alignment with the centre line of the steering swivel and wheel hub.

Wheel Plane

The plane (flat area) through the wheel at right angles to the axle.

Wheel Rim

Part of wheel that holds the tyre.

Wheel Slip (spin)

Loss of friction between a tyre and the road surface allowing the wheel to spin faster than the speed of the vehicle.

Wheel Track

The dimension between the centres of the road wheels on one axle. Also known as tread.

Wheelslip (Spin)

Loss of friction between a tyre and the road surface allowing the wheel to spin faster than the speed of the vehicle.

Whip (Whirl)

The throw out of a rotating shaft. In relation to drive shafts whip can create unpleasant harmonics and vibrations.


Tin based alloy used as a coating for plain steel bearings.


Standard size of thread. Old British standard.


Coil of wire used to create magnetism.


Coils of wire used to create magnetism when a current flows through them.

Wiring Harness (Loom)

The bundle of cables that are bound together to form the electrical distribution system for a vehicle or system.

Woodruff Key

A locating device that sits in slots on a shaft and pulley or gear wheel. Also known as a half-round key or in some cases just key!

Word Processor

A computer program used to create text based documents such as letters and memos, although graphics may also be added.


Performed when energy is used. The SI unit is the 'Joule'.

World Wide Web

The www is a collection of electronic 'pages' that can be accessed over the Internet. The World Wide Web is NOT the same as the Internet, it is only a part of it.

Worm Gear

Gear set with a screw pinion driving a wheel with meshing circumferential teeth.


Wide open throttle

Woven abrasive pad

A fibre pad used to lightly sand a surface. These pads, which are supplied in various grades, last much longer than abrasive papers and are less likely to rub through on sharp angles and panel edges.


The phenomenon by which electrically charged paint droplets curve around to the rear side of the object being painted. Used to great advantage in Electrostatic spraying of components with complicated shapes


Surface distortion that occurs in a thick coat of enamel due to uneven cure or recoating of an uncured paint film.

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