Chapter 1 Routine maintenance and servicing

REF•26 Glossary of technical termsautomatic transmission, a switch thatprevents starting if the vehicle is not in Neutralor Park.Strut See MacPherson strut.TTappet A cylindrical component whichtransmits motion from the cam to the valvestem, either directly or via a pushrod androcker arm. Also called a cam follower.Thermostat A heat-controlled valve thatregulates the flow of coolant between thecylinder block and the radiator, so maintainingoptimum engine operating temperature. Athermostat is also used in some air cleaners inwhich the temperature is regulated.Thrust bearing The bearing in the clutchassembly that is moved in to the release leversby clutch pedal action to disengage theclutch. Also referred to as a release bearing.Timing belt A toothed belt which drives thecamshaft. Serious engine damage may resultif it breaks in service.Timing chain A chain which drives thecamshaft.Toe-in The amount the front wheels arecloser together at the front than at the rear. Onrear wheel drive vehicles, a slight amount oftoe-in is usually specified to keep the frontwheels running parallel on the road byoffsetting other forces that tend to spread thewheels apart.Toe-out The amount the front wheels arecloser together at the rear than at the front. Onfront wheel drive vehicles, a slight amount oftoe-out is usually specified.Tools For full information on choosing andusing tools, refer to the Haynes AutomotiveTools Manual.Tracer A stripe of a second colour applied toa wire insulator to distinguish that wire fromanother one with the same colour insulator.Tune-up A process of accurate and carefuladjustments and parts replacement to obtainthe best possible engine performance.Turbocharger A centrifugal device, driven byexhaust gases, that pressurises the intake air.Normally used to increase the power outputfrom a given engine displacement, but canalso be used primarily to reduce exhaustemissions (as on VW’s “Umwelt” Dieselengine).UUniversal joint or U-joint A double-pivotedconnection for transmitting power from adriving to a driven shaft through an angle. A U-joint consists of two Y-shaped yokes and across-shaped member called the spider.VValve A device through which the flow ofliquid, gas, vacuum, or loose material in bulkmay be started, stopped, or regulated by amovable part that opens, shuts, or partiallyobstructs one or more ports or passageways.A valve is also the movable part of such adevice.Valve clearance The clearance between thevalve tip (the end of the valve stem) and therocker arm or tappet. The valve clearance ismeasured when the valve is closed.Vernier caliper A precision measuringinstrument that measures inside and outsidedimensions. Not quite as accurate as amicrometer, but more convenient.Viscosity The thickness of a liquid or itsresistance to flow.Volt A unit for expressing electrical “pressure”in a circuit. One volt that will produce a currentof one ampere through a resistance of oneohm.WWelding Various processes used to join metalitems by heating the areas to be joined to amolten state and fusing them together. Formore information refer to the HaynesAutomotive Welding Manual.Wiring diagram A drawing portraying thecomponents and wires in a vehicle’s electricalsystem, using standardised symbols. Formore information refer to the HaynesAutomotive Electrical and Electronic SystemsManual.1595 Ford Fiesta Remake