Automotive Terms Dictionary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Tachometer
An instrument for measuring the speed of the engine crankshaft in revolutions per minute (RPM).

TDI
Turbo Direct Injection Diesel

Tesla
After Nikola Tesla, a Croation born in what was then part of Austria-Hungary is now is Yugoslavia. He came to the U.S. at the age of 27, became an American citizen, and lived in the U.S. the rest of his life (1856-1943). The tesla is a unit of magnetic flux density, also called magnetic induction.

Throttle-Body
Throttle-Body Fuel Injection is a type of Electronic Fuel Injection which positions the injector(s) centrally in a throttle-body housing. This housing contains a valve to regulate the airflow through the intake manifold.

Timing
Timing refers to the crankshaft angles at which the valves open and close and at which time the ignition system fires the spark plugs.

Tire Rating and sizing
Tires are rated by load capacity, size and speed capacity. For example, a P225/60VR14 printed on the side of the tire means:
P = P-Metric (Passenger Type Tire)
255 = Section Width (255mm)
60 = Aspect Ratio (tire height/section width)
V = Speed Rating
R = Type of Ply (Radial)
14 = Wheel Diameter (14 inches)
Tire and wheel dimensions are the first point of information in any discussion of size and capacities. Among the other terms used to describe tires are: tread, shoulder, carcass, sidewall, bead seal, bead seat, tire diameter, aspect ratio, speed rating and section width.
Example:

235, 85 R16
235 is the width in mm.
85 refers to the height in percent of the width of the wheel that is the height.
So 85% of 235 is the tires height in mm.
R16 is the rim size, 16" rims.

Toe In
The amount by which the front of a front wheel points inward or outward. A slight amount of toe in is usually specified to keep the front wheels running parallel on the road by offsetting other forces that tend to spread the wheels apart.

Torque
A force that produces a twisting or rotating motion.

Torque Converter Clutch
An electronically controlled lockup clutch that is automatically engaged at certain speeds to eliminate the slip between the torque converter's input and output, thereby improving fuel efficiency and performance.

Torque, Engine
Engine torque is the amount of twisting effort exerted at the crankshaft by an engine expressed in foot-pounds of force. A foot-pound represents the force of one pound acting at the right angle to the rotating crankshaft at distance of one foot in length.

Torque Rating
A measure of the engine's power capability, whereby the amount of twisting or rotating effort being exerted on the crankshaft is expressed in lb.-ft. of force. Torque is the force that gets the weight of the vehicle moving, making it an important consideration in trailering.

Torsion Bar
A long straight bar fastened to the frame at one end and to a suspension part at the other. In effect, a torsion bar is merely an uncoiled spring, and spring action is produced by twisting the bar. The main advantage of the torsion bar over the coil spring in the front suspension is the ease of adjusting the front suspension height.

Traction Control
Traction control helps provide smoother, more controlled acceleration by reducing the amount of wheel spin during reduced traction conditions. Traction control utilizes the vehicle's anti-lock braking system and is usually activated only at low vehicle speeds.

Trailing Arm
A rear suspension element consisting of a lengthwise member that pivots from the body at its forward end and has a wheel hub rigidly attached to its trailing end.

Transaxle
A transmission and differential combined in one integrated assembly, eliminating the need for a separate connecting drive shaft. This configuration is typical in front-wheel-drive vehicles.

Tuned Intake and Exhaust Systems
Intake and exhaust systems that increase the flow of intake charge into and out of the combustion chambers by varying the length, shape, or diameter of the component.

Tuned-Port Fuel Injection
Tuned-Port Fuel Injection is almost identical to Multi-Port Fuel Injection, except that tuned runners are used to channel air to the cylinder heads. This results in increased airflow to the cylinders.

Turbocharger
Rotary compressor or pump that pressurizes engine intake air. It is driven by the flow of exhaust gases. The increased pressure forces more air into the cylinder than it could normally draw, allowing the engine to burn more fuel and in turn produce more power.