T

 

 

T & C

Transmission and Chassis Division

 

TACH

Abbreviation for tachometer, an instrument that indicates engine revolutions per minute.

 

TACHOGRAPH

A tachograph is a device which monitors and records various operating characteristics of a vehicle, including vehicle speed, total miles elapsed, engine RPM, total number of engine revolution-, ignition time on, vehicle movement time, and other data at the discretion of the owner.

 

TACHOMETER

A device, located on the instrument panel, that indicates the revolutions per minute of the engine's crankshaft.

 

TACTIC

Actions taken by a traffic unit to avoid a hazardous situation; steering, braking, accelerating, etc. to avoid a collision or other accident. Often called an evasive maneuver.

 

TAG AXLE

A non-driven (dead) axle installed behind the drive axle(s) to increase the permissible gross weight, and consequently the payload. Also termed "trailing axle."

 

TAKEOFF ANGLE (FALL OR VAULT)

The takeoff angle is the angle between the trajectory, or path, of the car and the horizontal in a fall or vault.

 

TAKEOFF POINT , FALL OR VAULT)

The takeoff point is the point at which vehicle leaves the ground in a fall or vault.

 

TAKEOFF SPEED

The takeoff speed of a vehicle which plunges off a precipice, embankment, terminal point in the road, bridge, or for some reason travels off the road and through the air, is the speed at which the vehicle leaves the surface.

 

TAMPER

A power driven machine for compacting ballast under ties.

 

TANDEM AXLE

A tandem axle set comprises two axles mounted closely enough together that they are treated as one axle for purposes of kinematic analysis or for purposes of loading analysis. The distance separation varies among the states: in the Federal Weight Law axles closer than 9 feet are designated as tandem axles.

 

TANDEM DRIVE

Two-axle drive combination.

 

TANGENT

A line that touches a curve at only one point and is perpendicular to the radius at that point; a term used to describe a straight offset method.

 

TANK CAR / TRAILER

A semi trailer consisting of a metal tank for carrying liquid or dry bulk. Also called a tanker.

 

TANK DOME

A vertical cylinder attached to the top of a tank car. It permits the tank proper to be filled to full cubical capacity, which would be impossible if there were no allowances for expansion in the dome.

 

TANKER

See tank trailer.

 

TAPE DRAWING

An outline of a car made with black pressure-sensitive tape, which can be easily seen, removed, and changed. Most often depicts the side elevation.

 

TAPER

Cone-shaped object or form.

 

TARE WEIGHT

(1) As applied to a loaded motor vehicle, tare weight is the weight of the vehicle exclusive of its contents. (2) Also refers to the weight on a container and or the material used for the container for packing the merchandise to be shipped.

 

TEAM TRACK

A track on which cars are placed for the use of the public in loading or unloading freight.

 

TECHNICAL FOLLOW-UP

Collection of additional facts from any source and organization and preliminary study of all available data relating to a traffic accident; level 3 of accident investigation.

 

TECHNICAL PREPARATION

Delayed traffic accident data collection and organization for study and interpretation. The data collected are essentially factual. Technical preparation includes making additional measurements and photographs, preparing maps and diagrams, simple speed estimates, matching damage areas, and making experiments to obtain specific data.

 

TEMPER

Heating and cooling of metal at desired rate to obtain desired strength or hardening properties.

 

TEMPLATE

An accurate surface profile taken from a blueprint or portion of a model to be duplicated. Can be made of cardboard, plastic, Masonite, plywood or metal, depending on proposed.

 

TEN-WHEELER

Three-axle truck having ten wheels.

 

TERMINAL

A building for the handling and temporary storage of freight as it is transferred between trucks, i.e., from a city pick up to a line haul truck.

 

TERMINAL CARRIER

The line haul motor carrier making delivery of a shipment at its destination Terminal carrier means the last or final carrier.

 

TEST LAMP

A device used to check an electrical circuit for problems.

 

TEST MATRIX

An organized array of tests based on many variable conditions and covering a complete given range.

 

TESTIMONY

Evidence given by a competent witness under oath or affirmation.

 

TFE

(Targets for Excellence) document to define GM quality expectations and to specify the supporting evidence that is required from both internal and external suppliers. TFE consists of six major evaluation areas: 1) Continuous Improvement; 2) Leadership; 3) Quality; 4) Cost; 5) Delivery; 6) Technology

 

TFU

Tool Follow Up Sheet, record of tools forecast for body program.

 

THEME SKETCH

A quick sketch to get an idea on paper; precedes a rendering.

 

THERMOSTAT

Device in cooling system to maintain water temperature within a definite range.

 

THREAD WIDTH

Distance between the centerline of front or rear tires measured at the ground.

 

THREE PIECE RIM

A three piece rim is a type of wheel used on trucks. The rim is made up of three pieces, the pieces being called the rim base, the side tins, and the lock rings

 

THREE POINT RESTRAINT

A lap and shoulder belt.

Throttle (% open)
Throttle position expressed as a percent where 0% is fully closed and 100% is open wide. ( Detroit )  

THROTTLE PLATE

The throttle plate is the circular (or nearly circular) plate in the throat of the carburetor which controls the volume of the air-fuel mixture delivered to the engine. The throttle plate is caused to rotate in the throat by motion of the throttle linkage.

 

THRUST

The force against a traffic unit considered to be concentrated on a particular point on that unit at any instant during a collision.

 

TIE PLATE

A metal plate at least six inches wide and long enough to provide a safe bearing area on the tie, with a shoulder to restrain outward movement of the rail.

 

TIE ROD

The tie rod in a steering system is a rod connected at one end to the drag link and at the other end to the steering knuckle. The tie rods, drag link idler arm and steering knuckles comprise the steering linkage.

 

TIER I SUPPLIER

Supplier who manufactures and sells product directly to Automotive OEMs.

 

TIER II SUPPLIER

Supplier who manufactures and sells products to a Tier I supplier to combine with other products for the Automotive OEMs.

 

TIG WELDING

Tungsten inert gas arc welding uses a non-consumable tungsten electrode with the weldment shielded from contamination by a jet of inert gas.

 

TIGER STRIPES

Vertical stripes predominantly observed in quarter panels and doors made of draw quality material requiring flex rolling. Flex roll mark appears each time coil is stopped for cutoff of blank.

 

TILT CAB

COE with facility to tilt cab forward for accessibility.

 

TIME TABLE

The authority for the movement of regular trains subject to the rules. It contains classified schedules with special instructions relating to the movement of trains and engines.

 

TIRE AXIS SYSTEM

The origin of the tire axis system is the center of the tire contact. The X 1-axis is the intersection of the wheel plane and the road plane with a positive direction forward. The Z 1-axis is perpendicular to the road plane with a positive direction downward. The Y 1-axis is in the road plane, its direction being chosen to make the axis system orthogonal and right-hand.

 

TIRE FOOTPRINT

The tire footprint is the part of the tire which is in contact with the road.

 

TIRE FORCES :

Aligning Stiffness (aligning torque stiffness)

TIRE FORCES :

Aligning Stiffness Coefficient (aligning torque coefficient)

TIRE FORCES :

Aligning Torque (Aligning Moment) (M z)

TIRE FORCES :

Braking (driving) Squeal

TIRE FORCES :

Braking (driving) Stiffness

TIRE FORCES :

Braking (driving) Stiffness Coefficient

TIRE FORCES :

Braking Force

TIRE FORCES :

Braking Force Coefficient

TIRE FORCES :

Braking Torque

TIRE FORCES :

Braking Traction Coefficient

TIRE FORCES :

Camber Force (Camber Thrust)

TIRE FORCES :

Camber Stiffness

TIRE FORCES :

Camber Stiffness Coefficient (camber coefficient)

TIRE FORCES :

Central Force

TIRE FORCES :

Conicity Force

TIRE FORCES :

Cornering Squeal

TIRE FORCES :

Cornering Stiffness

TIRE FORCES :

Cornering Stiffness Coefficient (cornering coefficient)

TIRE FORCES :

Drag Force

TIRE FORCES :

Driving Force

TIRE FORCES :

Driving Torque

TIRE FORCES :

Driving Traction Coefficient

TIRE FORCES :

First Order Lateral Force Variation

TIRE FORCES :

First Order Radial Force Variation

TIRE FORCES :

Harshness

TIRE FORCES :

Lateral Force

TIRE FORCES :

Lateral Force Coefficient

TIRE FORCES :

Lateral Force Offset

TIRE FORCES :

Lateral Force Variation

TIRE FORCES :

Lateral Traction Coefficient

TIRE FORCES :

Normal Force (F z)

TIRE FORCES :

Overturning Moment (M x)

TIRE FORCES :

Peak-to-Peak (total) Lateral Force Variation

TIRE FORCES :

Peak-to-Peak (total) Tidal Force Variation

TIRE FORCES :

Peak-to-Peak Lateral Tire Run-Out

TIRE FORCES :

Peak-to-Peak Lateral Wheel Run-Out

TIRE FORCES :

Peak-to-Peak Loaded Radial Tire Run-Out

TIRE FORCES :

Peak-to-Peak Radial Wheel Run-Out

TIRE FORCES :

Peak-to-Peak Unloaded Radial Tire Run-Out

TIRE FORCES :

Ply Steer Force

TIRE FORCES :

Radial Force Variation

TIRE FORCES :

Rolling Resistance Force

TIRE FORCES :

Rolling Resistance Force Coefficient

TIRE FORCES :

Rolling Resistance Moment (M y)

TIRE FORCES :

Roughness

TIRE FORCES :

Sizzle

TIRE FORCES :

Slap

TIRE FORCES :

Sliding Braking Traction Coefficient

TIRE FORCES :

Slip Angle Force

TIRE FORCES :

Squeal

TIRE FORCES :

The external force acting on the tire by the road having the following components: Longitudinal Force (F x): The component of the tire force vector in the X' direction.

TIRE FORCES :

Thump

TIRE FORCES :

Tire Force and Moment Stiffness

TIRE FORCES :

Tire Moments: The external moments acting on the tire by the road having the following components:

TIRE FORCES :

Tractive Force

TIRE FORCES :

Tread Noise

TIRE FORCES :

Vertical Load

TIRE FORCES :

Wheel torque (T)

 

TIRE FRICTION MARK

A tire mark made when a slipping or sliding tire rubs the road or other surface; skid marks; yaw marks; acceleration scuffs and flat tire marks.

 

TIRE LATERAL LOAD TRANSFER

The vertical load transfer from one of the front tires (or rear tires) to the other that is due to acceleration, rotational, or inertial effects in the lateral direction.

 

TIRE LATERAL LOAD TRANSFER DISTRIBUTION

The distribution of the total tire lateral load transfer between front and rear tires expressed as the percentage of the total.

 

TIRE LONGITUDINAL LOAD TRANSFER

The vertical load transferred from a front tire to the corresponding rear tire or vice versa that is due to acceleration, rotational, or inertial effects in the longitudinal direction.

 

TIRE MARK

A mark on a road or other surface by a tire on a vehicle; tire friction mark, imprint.

 

TIRE OVERALL WIDTH

The width of the unloaded new tire, mounted on specified rim, inflated to the normal recommended pressure, including protective rib, bars, and decorations. (See Tire and Rim Association Year Book.)

 

TIRE RATE

(static) The static rate measured by the change of wheel load per unit vertical displacement of the wheel relative to the ground at a specified load and inflation pressure.

 

TIRE SECTION HEIGHT

Half the difference between the tire outside diameter and the nominal rim diameter.

 

TIRE SECTION WIDTH

The width of the unloaded new tire mounted on specified rim, inflated to the normal recommended pressure, including the normal side walls but not including protective rib, bars, and decorations. (See Tire and Rim Association Year Book.)

 

TIRE TRACK

A mark left by a rotating tire being operated over a soft material, wet pavement, or material, or over heated asphalt. The tire tread pattern will show plainly.

 

TIRES, BELTED BIAS

Body plies are same as those for bias tires. In addition, tires have belt plies that constrict the diameter and give greater rigidity to the tread. Belts are heavier construction and the cords lie in a more circumferential direction than breakers on bias tires.

 

TIRES, BIAS

Body ply cords lie in a diagonal direction from bead to bead. Tires may also have narrow plies under the tread, called breakers, with cords that lie in approximately the same direction as the body ply cords.

 

TIRES, RADIAL

Body ply cords are placed perpendicularly across the tread from bead to bead. In addition, radial tries have belt plies that run circumferentially around the tire, under the tread. They construct the radial ply cords and give rigidity to the tread, resulting in less rolling resistance which gives better fuel economy.

 

TIRES, WIDE BASE

Same diameter as conventional tires, but have a wider base that provide greater ground contact. Sometimes used to replace dual tires, resulting in cost and weight savings.

 

TOE PAN

First break in the underbody between normal floor surface and front-of-dash. Usually roughly parallel to bottom of occupant's foot.

 

TOE-IN

The amount of inward tilt on most-forward part of front wheels relative to centerline of fore and aft track.

 

TOE-OUT

Opposite Toe-In

 

TOGGLE PRESS

A mechanical press of two or three slides actuated by toggle joints on the outer and crank shafts on inner slide or platen used for toggle drawing. Is often referred to as a draw press.

 

TOLERANCE

Permissible variation in dimension, weight, tic. For example, some states allow a tolerance in their maximum truck weight limits.

 

TONGUE

The tongue of a trailer is the extension forward of the trailer on which is mounted the hitch. The term is applied chiefly to trailers designed to be towed by automobiles.

 

TONGUE LOAD

The tongue load is the force transmitted by the hitch to the tongue of a trailer.

 

TON-MILE

A unit of measure. The movement of a ton of freight one mile. Ton-miles are computed by multiplying the weight in tons of each shipment transported by the distance hauled.

 

TONNAGE

Number of tons.

 

TOOL TRAIN

(Slang) Wreck train used for cleaning up derailments

Top Gear
The lowest ratio between Engine Speed and Road Speed. This value is set in the DDEC engine calibration file. It can be changed with the ProLink Diagnostic Data Reader or Detroit Diesel Diagnostic Link software. ( Detroit )

Top Gear -1
The second lowest ratio between Engine Speed and Road Speed. DDEC learns this ratio by monitoring Engine Speed and Road Speed as the vehicle moves. The date upon which the ratio was learned is recorded and displayed on the Vehicle Configuration report. ( Detroit )

Top Gear Cruise
The condition in which the vehicle was in Top Gear ~d in Cruise at the same time. ( Detroit )

Top Gear Distance
Distance traveled while in Top Gear. ( Detroit )

Top Gear Economy
Top Gear divided by Top Gear Fuel. ( Detroit )

Top Gear Fuel
Fuel consumed while driving in Top Gear. ( Detroit )

Top Gear Percentage
Top Gear Time divided by Driving Time ( Detroit )

Top Gear Time
Time accumulated during top gear driving in HH:MM:SS format. ( Detroit )

TORQUE

The product of the force and the perpendicular distance from the axis of rotation to the line of action of the force.

 

TORQUE BALANCE

Effectiveness Balance - That condition of design or adjustment where each pair of brakes on the axles of a vehicle or combination vehicle develop, at the same applied pressure, that proportion of torque consistent with the manufacturer's load rating of the axle. For purposes of interchange, this torque should be sufficient to develop 9 fpsps deceleration when 42 psi air is applied to the brake chambers when the axle is at rated load.

 

TORQUE BOX

Usually refers to a reinforced area of a frame which transmits torque loads.

 

TORQUE CONVERTER

A hydraulic drive which transmits power with ability to change torque.

 

TORQUE RODS

See stabilizers.

 

TORQUE-ARM CENTER IN BRAKING

The instantaneous center in a vertical longitudinal plane through the wheel center about which the wheel moves relative to the sprung mass when the brake is locked.

 

TORQUE-ARM CENTER IN DRIVE

The instantaneous center in a vertical longitudinal plane through the wheel center about which the wheel moves relative to the sprung mass when the drive mechanism is locked at the power source.

 

TORQUE-ARM RADIUS

The horizontal distance from the torque-arm center to the wheel center.

 

TORQUE-MOMENT

A measure of the effectiveness of a force in producing rotation about the axis.

 

TORSION BAR

A torsion bar is an element of a suspension system performing the same function as a spring. A torsion bar is a long straight rod secured at one end to the chassis of the vehicle and it the other end to a lever arm. By twisting the lever arm around the axis of the rod, a force is developed at the end of the lever arm. As installed in the vehicle, the force is used to support the vehicle, and the twisting of the rod performs the "springing" function of the torsion bar.

 

TORSION SPRINGS

Spring effect developed through torsional stress in steel rod(s).

 

TORSIONAL SHAKE

A mode of vibration involving twisting deformations of sprung mass about the vehicle x-axis.

 

TORSO LINE

Line parallel to the small of the manikin's back through the "H" point.

 

TORSO TEMPLATE

A two-dimensional plastic template of the male manikin used to establish the "T" point or head room when designing the body interior package.

Total Alerts
Number of engine diagnostic alerts that occurred. Up to the last five check engine alerts and the last five stop engine alerts are saved and may be reported on the Alerts report. ( Detroit )

TOTAL STATIC DEFLECTION

Total static deflection of a loaded suspension system is the overall deflection under the static load from the position at which all elastic elements are free of load.

 

TOTAL STOPPING DISTANCE

Total stopping distance is the distance traveled by the vehicle from the moment the driver first detects a hazard until the vehicle comes to rest.

 

TOW BAR

Bar or V-shaped device attached to the chassis of a trailer dolly or front axle.

 

TOWED VEHICLE

A motor vehicle that was involved in an accident and removed from the scene by means other than its own power.

 

TOWER

Building of sufficient height erected along right-of-way to permit maximum viewing. May house yard master, switch lever operator, block operator, or dispatcher.

 

TOW-IN

The amount of distance which the front of the front wheels are closer together than the rear of the wheels. Front tires are toed-in to improve steering and increase tire life.

 

TPO

Thermoplastic olefin - type of plastic used for injection molded plastic parts.

 

"T" Point

A point located on the head of the torso template which represents 30 inches of effective headroom when the template is located in the correct seated position.

 

TPU

Thermoplastic urethane - type of plastic used for injection molded plastic parts.

 

TQE

(Total Quality Excellence) is Ford's highest recognition of full-service suppliers. It represents a superior level of excellence and continuous improvement in everything suppliers do to meet Ford customer's needs and expectations.

 

TQM

(Total Quality Management) A process approach to quality which holds each person in the organization responsible for their personal output.

 

TRACK

1) The distance on the ground between the center of the tire tread on one side of the vehicle to the center of the tire tread on the opposite side. 2) The space between the rails and space of not less than 4' outside each rail.

 

TRACK CAR

A self propelled car including; Burro cranes, Highway rail cars, Detector cars, Weed burners, Tie tampers, and other similar equipment. This type of equipment may not operate signals or shunt track circuits.

 

TRACK CHANGE

The change in wheel track resulting from vertical suspension displacements of both wheels in the same directions.

 

TRACK CIRCUIT

An electrical circuit which includes the rails and wheels of the train. Used for controlling signaling devices (fixed signals as well as flashers and gates at crossings).

 

TRACK WIDTH

The distance between the front wheels and/or the distance between the rear wheels. Measured from the center of the tire along the lateral axis.

 

TRACK, AXLE

Distance between centerlines or tire tread at ground on front or rear axles.

 

TRACKING

Marks made when tires roll through puddles, run-off, or splatter and, becoming wet, leave tire prints on the pavement as they roll on.

 

TRACTION FORCE

The adhesive friction of a body, such as a tire, on a surface, such as a roadway, that keeps the body from slipping on the surface. Traction breaks and slipping begins when another force, such as breaking force and centrifugal force exceeds traction force.

 

TRACTION GRADE (OF A TIRE)

The traction grade represents a tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete.

 

TRACTION-LIMITED GRADE

Steepest negotiable grade where traction is the limiting factor.

 

TRACTIVE EFFORT

1) The maximum force developed by vehicle powertrain at contact between driven wheels and road surface with 100% traction. 2)The amount of power required to move a vehicle.

 

TRACTIVE FORCE

The tractive force is that part of the friction force on the tires which is directed along the vehicle centerline.

 

TRACTOR

Truck portion of combination or train.

 

TRACTOR PROTECTION VALVE

Controls flow of compressed air from tractor to trailer when closed, stops flow of air to trailer. When this happens, the trailer brakes will apply. Used to make sure that air is always available for tractor brakes. Must be in "Normal" position when tractor is hooked up to trailer and in "Emergency" position to unhook trailer.

 

TRAFFIC

Pedestrians, ridden or herded animals, vehicles, street cars, and other conveyances either singly or together while using any highway for purposes of travel.

 

TRAFFIC ACCIDENT

An accident involving travel or transportation on a traffficway.

 

TRAFFIC CONTROL SYSTEM

A block signal system under which train movements are authorized by block signals, whose indications supersede the superiority of trains from both opposing and following movements on the same track.

 

TRAFFIC UNIT

An element of traffic; a person using a trafficway for travel or transportation; vehicle; pedal cycle, pedestrian, etc.

 

TRAFFICWAY

The entire width between property lines, or other boundary lines, of every way or place of which any part is open to the public for purposes of vehicular travel as a matter of right or custom. All highways are trafficways include also some areas on private property such as shopping centers.

 

TRAIL

The horizontal distance from the point where the steer axis intersects the roadway to the center of the tire contact patch.

 

TRAILER

Every vehicle with or without motive power, other than a pole trailer, designed for carrying persons or property and for being drawn by a motor vehicle and so constructed that no part of its weight rest upon the towing vehicle.

 

TRAILER BRAKE

A hand-operated remote control that applies trailer brakes only. Located on the steering column or dash. Must never be used for parking. Also called hand valve, trolley brake, trolley valve handle, trailer hand brake, and independent trailer brake.

 

TRAILER HAND BRAKE

See trailer brake.

 

TRAILER, FULL

Truck trailer constructed so that all its own weight and that of its load rests upon its own wheels.

 

TRAILING MOVEMENT

The movement of a train over the points of a switch which face in the direction in which the train is moving.

 

TRAILING POINT SWITCH

A switch, the points of which face away from approaching traffic.

 

TRAIN

An engine or more than one engine coupled, with or without cars, displaying a marker.

 

TRAJECTORY

Trajectory is defined as the curve which a body follows as it moves through space. The path is curved because the horizontal velocity is constant and the vertical velocity due to gravity is changing. The path through space derived from the vector summation of these two velocities is curved.

 

TRAMP

The form of wheel hop in which a pair of wheels hop in opposite phase.

 

TRANSFER CASE

Split power gear box transmitting drive to front and rear axles.

 

TRANSFER DIE

A multi-operation die in which the panel progresses from stage to stage by means of a transfer device.

 

TRANSFER PUMP

A pump used to move fuel from fuel tank to injectors or carburetor.

 

TRANSIENT STATE

Transient state exits when the motion responses, the external forces relative to the vehicle, or the control positions are changing with time.

 

TRANSIENT VIBRATION

Transient vibration exists in a system when one or more component oscillations are discontinuous.

 

TRANSIENT-HIGH ENERGY

A voltage spike on the power supply line of very high voltage and long time duration (I.e. load dump which is losing a battery connection while changing the battery).

 

TRANSIENT-LOW ENERGY

A voltage spike on the power supply line of very high voltage and short time duration (I.e. the inductive load caused by the field collapsing in a solenoid.)

 

TRANSLATIONAL MOTION

Motion of a rigid body in such a way that any line which is imagined rigidly attached to the body remains parallel to its original direction.

 

TRANSMISSIBILITY

Transmissibility in forced vibration is the ratio of the transmitted force to the applied force.

 

TRANSMISSION (Auxiliary)

Additional gearbox increasing the gear ratio combinations when used with main transmission or multi-speed axles.

 

TRANSMISSION (Main)

Selective gear box providing various combinations of gear ratios.

 

TREAD

Tread is that portion of a tire that comes into contact with the road. The peripheral portion of the tire, the exterior of which is designed to contact the road surface.

 

TREAD ARC WIDTH

The distance measured along the tread contour of an unloaded tire between one edge of the tread and the other. For tires with rounded tread edges, the point of measurement is that point in space which is at the intersection of the tread radius extended until it meets the prolongation of the upper side wall contour.

 

TREAD CONTACT LENGTH

The perpendicular distance between the tangent to edges of the leading and following points of road contact and parallel to the wheel plane.

 

TREAD CONTACT WIDTH

The distance between the extreme edges of road contact at a specified load and pressure measured parallel to the Y' axis at zero slip angle and zero inclination angle.

 

TREAD CONTOUR

The cross sectional shape of tread surface of an inflated unloaded tire neglecting the tread pattern depressions.

 

TREAD CORD WIDTH

The distance measured parallel to the spin axis of an unloaded tire between one edge of the tread and the other. For tires with rounded tread edges, the point of measurement is that point in space which is at the intersection of the tread radius extended until it meets the prolongation of the upper side wall contour.

 

TREAD DEPTH

The distance between the base of a tire tread groove and a line tangent to the surface of the two adjacent read ribs or rows.

 

TREAD PATTERN

The molded configuration on the face of the tread. It is generally composed of ribs, rows, grooves, bars, lugs, and the like.

 

TREAD PITCH

Tread pitch is the length between corresponding points along a tire tread.

 

TREAD RADIUM

The radius or combination of radii describing the tread contour.

 

TREAD RIB

Tread rib is a tread section running circumferentially around a tire.

 

TREAD SEPARATION (OF A TIRE)

Tread separation is the pulling away of the tread from the tire carcass.

 

TREAD WEAR GRADE

The tread wear grade is a comparative rating based on the wear ratio of a tire when tested under controlled conditions on a specified government test course.

 

TREADLE VALVE

A foot-operated air service brake actuation valve.

 

TRIANGULATION

A method of locating a spot in an area by measurements from two or more reference points, the locations of which are identified for future reference.

 

TRI-AXLE

An assembly of three rear axles, any or all of which may be powered.

 

TRI-DRIVE

Vehicle having three rear axles driving.

 

TRIKE

A three wheeled motorcycle which has a single front wheel operating similarly to the front wheel of a motorcycle and two rear wheels similar to those of an automobile.

 

TRIM - THE STEADY STATE

(that is, equilibrium) condition of the vehicle with constant input which is used as the reference point for analysis of dynamic vehicle stability and control characteristics.

 

TRIM BUCK

A full-sized model of an interior to show the design of a specific model.

Trip
An accumulation of data from extraction to extraction. ( Detroit )

Trip Calendar Time
Total Time between extractions including Engine Off Time. ( Detroit )

Trip Distance
The total miles traveled during a Trip. ( Detroit )

Trip Fuel
The total fuel used during a Trip. ( Detroit )

TRIP RISK

The danger to a traffic unit in undertaking a particular trip; the combined effect of road, vehicle, driver, weather, traffic, and schedules on the possibility of maintaining adequate driving strategy and evasive tactics.

Trip Status
A category in the Extraction Log which reports inconsistencies in Trip data. ( Detroit )

Trip Time
Time while engine was running during a Trip. ( Detroit )  

TRIPLE LOAD

A shipment requiring the use of two carrying cars with an idler car between them.

 

TRIPLE TREE

The steering head assembly which connects the top of the fork to the frame and handlebar.

 

TRIPLES

A combination consisting of a tractor, a semi-trailer and two full trailers, coupled together. Known as triple headers or triple bottoms.

 

TROLLEY BRAKE

See trailer brake.

 

TROLLEY-VALVE HANDLE

Operates the trailer's brakes. See trailer brake.

 

TRPO

Truck and Recreation Products Office

 

TRUCK

1) Every motor vehicle designed, used, or maintained primarily for the transportation of property. 2) A general term for the complete four wheel freight car assembly which supports the car body at each end. It is attached to the body by a pair of center plates which function as a pivot. See center plate.

 

TRUCK TRACTOR

Every motor vehicle designed and used primarily for drawing other vehicles and not so constructed as to carry a load other than part of the weight of the vehicle and load so drawn.

 

TRUNNION

Journals allowing pivoting or turning such as tandem axle spring or walking beam assembly.

 

TSA

(Temporary Substitution Approval) document generated by Chrysler Plant or Corporate Product Engineering that allows a product with a deviation in a characteristic to be received and used in an assembly plant for a specific length of time.

 

TSCA

Toxic Substance Control Act

 

TTL

Transistor, Transistor Logic, a digital logic system where the gates consist of mostly transistors.

 

TUBELESS TIRE

A tubeless tire is a pneumatic tire in which the casing is sealed directly to the wheel rim, precluding the necessity for an inner tube.

 

TULIP PANEL

Exterior body panel located between the backlight opening and the deck lid opening.

 

TUMBLEHOME

Angle of the "B" pillar and side glass from the perpendicular at the beltline, as seen from front or rear.

 

TUNNEL

The hump in the floor pan that provides clearance for the driveshaft.

 

TUNNEL VISION

Tunnel vision is an eye condition in which objects alerts the aide of the road, or objects approaching the road from the side, are less likely to be seen, especially if the objects are dark and reflect a minimum of light.

 

TURBINE ENGINE

An engine in which the working medium is a gaseous fluid throughout the cycle with the principal mechanical parts driven by turbines.

 

TURBOCHARGER

A type of blower, powered by engine exhaust gases, that forces air into the intake manifold at higher than atmospheric pressure to increase engine power and performance. See blower.

 

TURBULENCE

Swirling charge of fuel and air in combustion chamber.

 

TURN AROUND

A type of trip or "run" in which the driver returns to the origin point immediately after his vehicle is unloaded and reloaded.

 

TURNING CIRCLE

Twice the turning radium.

 

TURNING RADIUS

Radius of minimum turning circle.

 

TURNPIKE

Expressway or freeway.

 

TURNUNDER

Opposite of tumblehome. The inward and downward sweep of sheet metal from the widest point on a car down to the rocker panel.

 

TWEAK BAR

An after market device mounted on the fork tubes for stability in addition to that provided by the fender brace.

 

TWILIGHT

Three phases of twilight separate daylight from full darkness, based on functional changes in visual capability. Ambient illumination falls continuously during the three phases, which are referred to as (1) Civil Twilight, (2) Nautical Twilight, (3) Astronomical Twilight. Each phase corresponds to a solar transit of six degrees below the horizon and each phase last about 30 minutes in the middle latitudes of North America. (a) Civil Twilight occurs after sunset and before sunrise, when the upper limb of the sun is tangent with the horizon, and the moment when the center of the sun is 6 below the horizon. (b) Nautical Twilight occurs when the sun is between six and twelve degrees below the horizon. During this phase there is ample light to visual the horizon for navigation at sea, but insufficient light for many other outdoor activities. (c) Astronomical Twilight occurs when the sun is between twelve and eighteen degrees below the horizon. This phase approaches the darkness of full night when illumination from the sun is lower than that from the stars.

 

TWIN SCREW

Truck with tandem drive axles.

 

TWO PIECE RESTRAINT

A lap belt.

 

TWO PIECE RIM

A two piece rim is a type of wheel used on trucks. The wheel is designed in two pieces, the pieces being called the rim base and the side ring.

 

TWO STROKE CYCLE

The cycle of an engine which accomplishes the intake, compression, power and exhaust phases in to strokes of the piston. An engine with such a cycle is also called two cycle or two stroke engine.

 

TWO-SPEED AXLE

A drive axle capable of being shifted through two gear ranges in order to double the number of gears available from the transmission.

References

Detroit Diesel

Caterpillar User's Manual