Terms Starting with T


Tachometer-A meter used to measure the speed of a rotating shaft.

Tappet-Another term for valve lifter.

TDC-Position of the piston at top dead center.

Tensile strength-The amount of pressure per square inch a bolt can withstand just before breaking when being pulled apart.

Thermal efficiency-A measure of how effectively an engine converts heat energy in fuel into mechanical energy at the rear of the engine.

Thermistor-A sensor that is able to change electrical resistance because of a change in temperature.

Thermostat-The part on a cooling system that controls the engine coolant to its highest operating temperature.

Thermostatic switch-A heat-sensitive switch used to turn on and off an air-conditioning compressor.

Threads per inch-A number used to identify bolts by the number of threads per inch.

Throttle body-A part of a fuel system where fuel is injected into the air stream.  The throttle body injector is located above the throttle plate.

Throttle plate-The plate or circular disk that controls the amount of air going into the engine.  It is controlled by the position of the operator’s foot.

Throttle valve (TV)-A valve used in the automatic transmission that changes oil flow based on the position of the engine throttle.

Throw-The distance from the center point of the crankshaft to the center point of the connecting rod.

Thrust bearing-An antifriction bearing designed to absorb thrust along the axis of the rotating shaft.

Thrust load-An axial load of a rotating shaft.

Thrust plate-The plate used to bolt the camshaft to the block, which absorbs camshaft thrust.

Timing-The process of identifying when air, fuel, and ignition occur in relation to the crankshaft rotation.

Timing diagram-A graphic diagram used to identify the time in which all of the events of the four-stroke engine operate.

Toe (in, out)-The inward or outward pointing of the front wheels as measured in inches or millimeters.

Torque-A twisting force applied to a shaft or bolt.

Torque converter-The coupling between the engine and transmission on an automatic transmission.  It is also used to multiply torque at lower speeds.

Torque converter clutch-A valve used in conjunction with the lockup clutch mechanism on an automatic transmission.

Torque-to-yield bolt-A bolt that has been tightened by the manufacturer to a preset yield or stretch point.

Torsional rings-Piston rings that have a slight twist when placed within the cylinder wall.  These are made by adding a chamfer or counter bore on the ring.

Torsional vibration-A vibration produced on a spinning shaft caused by torque applied to the shaft.

Traction-A tire’s ability to hold or grip the road surface.

Transducer-A device on many electrical computer circuits that uses one type of energy as the input and another type of energy as the output, such as a piezoelectric crystal that uses motion as the input and electricity as its output.

Transistor-A semiconductor used in electrical circuits to turn a second circuit off or on.  Also used to amplify an electrical signal.

Transmission band-A type of hydraulic clutch that uses a metal band fitted around a clutch housing.  As the band is tightened, the clutch housing is stopped.

Tread bars-Narrow strips of rubber molded into the tread.  When the tread bars show, the tire is worn enough to be replaced.

Trouble code-A code stored inside a vehicle’s computer that tells the exact component that is faulty.

Trunnion-The arms of the four-point U-joint which serves as the inner bearing surface or race.

Tuned ports-Intake ports used on fuel injection engines designed to produce equal and minimum restriction to the airflow flowing into the engine.

Turbine-The rotary part or vaned wheel inside a torque converter, used to turn the transmission gears and clutches.

Turbocharger-A device that uses the energy in the engine exhaust gases to turn a compressor, which pumps more air into the engine.

Turbulence-A term used to describe combustion chambers.  It means rapid movement and mixing of air and fuel inside the combustion chamber.

Turning radius-The amount (in degrees) that one front wheel turns more sharply than the other front wheel.


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