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Truck Accident Glossary of Terms
[A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [O] [P] [R] [S] [T] [U] [V] [W] [Y]
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- Drive axles are those with powered wheels.
- Front axle is usually called the steer axle.
- Pusher axles are unpowered and go ahead of drive axles.
- Rear axles may be drive, tag or pusher types.
- Tag axles are unpowered and go behind drive axles.
ABS (Antilock Braking System) Computer,
sensors and solenoid valves which together monitor wheel speed and
modulate braking force if wheel lockup is sensed during braking. Helps
the driver retain control of the vehicle during heavy braking on
slippery roads. AFV (Alternative Fueled Vehicle) Vehicle powered by a fuel other than gasoline or diesel. Air Ride Suspension Suspension
which supports the load on air-filled rubber bags rather than steel
springs. Compressed air is supplied by the same engine-driven air
compressor and reservoir tanks which provide air to the air brake
system. ATC (Automatic Traction Control) Usually an
optional feature based on ABS, it prevents spinning of the drive wheels
under power on slippery surfaces by braking individual wheels and/or
reducing engine throttle. Also called ASR, an acronym sometimes loosely
translated from the German as anti-spin regulation. ATV (All Terrain Vehicle) Vehicle designed for any type of terrain. AVI (Automatic Vehicle Identification) System
combining an on-board transponder with roadside receivers to automate
identification of vehicles. Uses include electronic toll collection and
stolen vehicle detection. (see IVHS ) AVL (Automated Vehicle Location) Class
of technologies designed to locate vehicles for fleet management
purposes and for stolen vehicle recovery. Infrastructure can be
land-based radio towers or satellites. (see IVHS ) Axle Structural component to which wheels, brakes and suspension are attached.
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BBC Distance from a truck's front bumper to the back of its cab. Bill of Lading Itemized list of goods contained in a shipment. Blind Spot Areas around a commercial vehicle that are not visible to the driver either through the windshield, side windows or mirrors. Bobtail Tractor operating without a trailer. Also refers to straight truck. Bogie (also spelled bogey) Assembly of two or more axles, usually a pair in tandem. Brake Horsepower (bhp) Engine horsepower rating as determined by brake dynamometer testing. (see Horsepower) Bridge Formula A
bridge protection formula used by federal and state governments to
regulate the amount of weight that can be put on each of a vehicle's
axles, and how far apart the axles (or groups of axles) must be to
legally carry a given weight. Bunk See Sleeper .
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Cabover (Cab-Over-Engine, COE) Truck or tractor design in which the cab sits over the engine on the chassis. Cargo Weight Combined weight of all loads, gear and supplies on a vehicle. Cartage Company Company that provides local (within a town, city or municipality) pick-up and delivery. Cast Spoke Wheel Wheel with five or six spokes originating from a center hub. The spoked portion, usually made of cast steel, is bolted to a multiple-piece steel rim (see Demountable Rim; Disc Wheel). CB (Citizens Band Radio) Two-way radio for which no license is required by the Federal Communications Commission (FCC). Long beyond its heyday in the '70s, CB is still used by truckers and motorists for everything from traffic condition reports to emergency calls to idle chatter. CDL (Commercial Driver's License) License which authorizes an individual to operate commercial motor vehicles and buses over 26,000 pounds gross vehicle weight. For operators of freight-hauling trucks, the maximum size which may be driven without a CDL is Class 6 (maximum 26,000 pounds gross vehicle weight). CE (CF, LP) Distance from back of a truck's cab to the end of its frame. CFC Chlorofluorocarbon. CG (Center of Gravity) Weight center or balance point of an object, such as a truck body. Calculated to help determine optimum placement of truck bodies on chassis. Chassis Weight (Curb Weight, Tare Weight) Weight of the empty truck, without occupants or load. CNG Compressed natural gas. COE See Cabover . COFC (Container On Flat Car) Method of moving shipping containers which involves transporting them on railroad flat cars. Common Carrier Freight transportation company which serves the general public. May be regular route service (over designated highways on a regular basis) or irregular route (between various points on an unscheduled basis). Compensated Intracorporate Hauling Freight transportation service provided by one company for a sister company. Container (Shipping Container) Standard-sized rectangular box used to transport freight by ship, rail and highway. International shipping containers are 20 or 40 feet long, conform to International Standards Organization (ISO) standards and are designed to fit in ships' holds. Containers are transported on public roads atop a container chassis towed by a tractor. Domestic containers, up to 53 feet long and of lighter construction, are designed for rail and highway use only. Container Chassis Single-purpose semitrailer designed to carry a shipping container. Contract Carrier Company that transports freight under contract with one or a limited number of shippers. Converter Dolly (Dolly) Auxiliary axle assembly equipped with a fifth wheel (coupling device), towed by a semitrailer and supporting the front of, and towing, another semitrailer. Cube (Cubic Capacity) Interior volume of a truck body, semitrailer or trailer, measured in cubic feet. Curb Weight See Chassis Weight .
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Dead-Heading Operating a truck without cargo. Demountable Rim Multi-piece
steel wheel rim assembly which is bolted to a spoke hub. Demountable
rims are still in use, though they have been replaced in many
applications by the simpler disc wheel. (see Cast Spoke Wheel) Disc Wheel Single-piece
rim/wheel assembly of stamped and welded steel or forged aluminum,
anchored by 8 or 10 nuts to a hub. A "Budd wheel" is a ten-hole,
stud-piloted disc wheel; a design originated by the Budd Corporation. Displacement (Piston Displacement) Sum
of the volumes swept by an engine's pistons as they travel up and down
in their cylinders. Based upon bore (diameter of cylinder) and stroke
(distance traveled by piston). Expressed in liters or cubic inches. Dolly See Converter Dolly . Doubles (Twins, Twin Trailers) Combination of a tractor and two semitrailers connected in tandem by a converter dolly. (see Converter Dolly ; Pintle Hook ) Driveline All
the components which together transmit power from the transmission to
the drive axle(s). These consist of at least one driveshaft (propeller
shaft) with a universal joint at each end. Drivetrain (Powertrain) All
the components, excluding engine, which transmit the engine's power to
the rear wheels: clutch, transmission, driveline and drive axle(s).
(See Powertrain ) DRL (Daytime Running Lights) System that automatically turns on a vehicle's low beam headlights when the parking brake is released and the ignition is on.
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EDI (Electronic Data Interchange) The
business-to-business interconnection of computers for the rapid
exchange of a wide variety of documents, from bills of lading to build
tickets at auto plants. Escape Ramp See Runaway Truck Ramp . Exempt Carrier Company which transports commodities exempted from Interstate Commerce Commission (ICC) economic regulation. EV (Electric Vehicle) Vehicle
powered by electric motor(s) rather than by an internal combustion
engine. Most common source of electricity is chemical storage
batteries.
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Fifth Wheel Coupling
device attached to a tractor or dolly which supports the front of a
semitrailer and locks it to the tractor or dolly. The fifth wheel's
center is designed to accept a trailer's kingpin, around which the
trailer and tractor or dolly pivot in turns. Fixed Tandem Assembly of two axles and suspension that is attached to the chassis in one place, and cannot be moved fore and aft. (see Sliding Tandem ) For-Hire Carrier Company in the business of transporting freight belonging to others (see Private Carrier ).
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GAWR (Gross Axle Weight Rating) Maximum
weight an axle is rated to carry by the manufacturer. Includes both the
weight of the axle and the portion of a vehicle's weight carried by the
axle. GCW (Gross Combination Weight) Total weight of a loaded combination vehicle, such as a tractor-semitrailer or truck and full trailer(s). Geared Speed Calculated vehicle speed at the engine's governed rpm in each transmission gear, or (commonly) in top gear. Gear Ratio Number,
usually expressed as a decimal fraction, representing how many turns of
the input shaft cause exactly one revolution of the output shaft.
Applies to transmissions, power takeoffs, power dividers and rear
axles. Example: If 2.5 revolutions of an input shaft cause one
revolution of the output shaft, the gear ratio is 2.5:1. Grade Steepness
of a grade, expressed as a percentage. Example: A vehicle climbing a 5%
grade rises 5 feet for every 100 feet of forward travel. Gradeability Vehicle's
ability to climb a grade at a given speed. Example: A truck with a
gradeability of 5% at 60 mph can maintain 60 mph on a grade with a rise
of 5%. GVW (Gross Vehicle Weight) Total weight of a vehicle and everything aboard, including its load. GVWR (Gross Vehicle Weight Rating) Total weight a vehicle is rated to carry by the manufacturer, including its own weight and the weight of its load.
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Hazmat Hazardous
materials, as classified by the U.S. Environmental Protection Agency
(EPA). Transport of hazardous materials is strictly regulated by the
U.S. Department of Transportation. Headache Rack Heavy
protective barrier mounted behind the tractor's cab. Designed to
prevent "headaches" caused by load shifting forward from the trailer
and crushing the cab. HCFC Hydrochlorofluorocarbon. Horsepower (hp) Measure
of power (the amount of work that can be done over a given amount of
time). One horsepower is defined as 33,000 foot-pounds of work in one
minute. Example: Lifting 33,000 pounds one foot in one minute, or
lifting 3300 pounds ten feet in one minute. Horsepower, Gross Laboratory Tested horsepower of a "bare" engine without fan, water pump, alternator, exhaust system or any other accessories. Horsepower, SAE Net Horsepower
capability of an engine with full accessories and exhaust system. Test
procedures per standards of Society of Automotive Engineers (SAE). Hours-Of-Service U.S.
Department of Transportation safety regulations which govern the hours
of service of commercial vehicle drivers engaged in interstate trucking
operations.
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- Advanced Public Transportation Systems (APTS)
- Advance Traffic Management Systems (ATMS)
- Advance Traveler Information Systems (ATIS)
- Advanced Vehicle Control Systems (AVCS)
- Commercial Vehicle Operations (CVO)
Independent Trucker See Owner Operator . ITS (Intelligent Transportation Systems) See IVHS . IVHS (Intelligent Vehicle Highway Systems) Blanket
term for a wide array of technologies, including electronic sensors,
computer hardware and software and radio communications. The purpose of
IVHS is to increase efficiency of use of existing highways, reducing
travel time, fuel consumption, air pollution and accidents. There are
five functional areas:
A more recently coined term, Intelligent Transportation Systems (ITS), encompasses both IVHS and modes of transportation other than highway, such as rail. (see AVI , AVL , WIM )
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Jacknife To place the trailer at a very sharp angle to the tractor. Jake Brake See Retarder . JIT (Just-In-Time) Manufacturing system which depends on frequent, small deliveries of parts and supplies to keep on-site inventory to a minimum.
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Kingpin (axle) Pin around which a steer axle's wheels pivot. Kingpin (trailer) Anchor
pin at the center of a semitrailer's upper coupler which is captured by
the locking jaws of a tractor's fifth wheel to attach the tractor to
the semitrailer.
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Landing Gear Retracting legs which support the front of a semitrailer when it is not coupled to a tractor. LCV (Long Combination Vehicle) In
general, vehicles longer than a standard doubles rig (tractor and two
28-foot semitrailers). Examples of LCVs which are permitted in some
U.S. western states and eastern toll roads: Twin 48-foot trailers;
triple 28-foot trailers. Lessee Company or individual which leases vehicles. Lessor Company which leases vehicles. Lift Axle Extra,
unpowered axle needed only when the vehicle is loaded, allowing it to
meet federal and state vehicle weight standards. The lift axle is
mounted to an air spring suspension that raises the axle when it is not
required. LPG Liquid propane gas. Load Range (Tires) Letter code system for the weight carrying capacity of tires. Comparable ply ratings are shown below. LR PR LR PR A .... 2 E .... 10 B .... 4 F .... 12 C .... 6 G .... 14 D .... 8 H .... 16 (LR = Load Range PR = Ply Rating) Logbook Book
carried by truck drivers in which they record their hours of service
and duty status for each 24-hour period. Required in interstate
commercial trucking by the U.S. Department of Transportation. Lowboy Open flat-bed trailer with a deck height very low to the ground, used to haul construction equipment or bulky or heavy loads. LTL (Less-Than-Truckload) A
quantity of freight less than that required for the application of a
truckload (TL) rate; usually less than 10,000 pounds. (see TL ) LTL Carrier Trucking company which consolidates less-than-truckload cargo for multiple destinations on one vehicle. (see TL Carrier )
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On-Board Computer See Trip Recorder . Overdrive Gearing
in which less than one revolution of a transmission's input shaft
causes one turn of the output shaft. The purpose of overdrive is to
reduce engine rpm in high gear for better fuel economy. Example: A
transmission with an overdrive top gear has a ratio of 0.70 to one.
Turning the input shaft 0.7 revolutions causes 1.0 revolution of the
output shaft. Owner-Operator Trucker who owns and operates his own truck(s).
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P&D Pickup and delivery. Payload Weight of the cargo being hauled. Peddle Run Truck route with frequent delivery stops. Pigtail Cable used to transmit electrical power from the tractor to the trailer. So named because it is coiled like a pig's tail. Piggyback Semitrailer built with reinforcements to withstand transport by a railroad flatcar. (see TOFC ) Pintle Hook Coupling
device used in double trailer, triple trailer and truck-trailer
combinations. It has a curved, fixed towing horn and an upper latch
that opens to accept the drawbar eye of a trailer or dolly. Piston Displacement See Displacement . Ply Rating (PR) Relative measure of tire casing strength. (see Load Range) Powertrain See Drivetrain . Private Carrier Business
which operates trucks primarily for the purpose of transporting its own
products and raw materials. The principle business activity of a
private carrier is not transportation. (see For-Hire Carrier) PSI (Pounds Per Square Inch) In trucking, unit of measurement for tire air pressure, air brake system pressure and turbocharger boost. PTO (Power Takeoff) Device
used to transmit engine power to auxiliary equipment. A PTO often
drives a hydraulic pump, which can power a dump body, concrete mixer or
refuse packer. Some designs mount to a standard opening on the
transmission, while others attach at the front or rear of the engine. Pull Trailer Short, full trailer (supported by axles front and rear) with an extended tongue. Pup Trailer Short semitrailer, usually between 26 and 32 feet long, with a single axle. Pusher Axle See Axle .
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Relay (Relay Driving) Common
practice in the less-than-truckload industry, in which one driver takes
a truck for 8 to 10 hours, then turns the truck over to another driver,
pony express style. Reefer Refrigerated trailer with insulated walls and a self-powered refrigeration unit. Most commonly used for transporting food. Retarder Device
used to assist brakes in slowing the vehicle. The most common type of
retarder on over-the-road trucks manipulates the engine's valves to
create engine drag. (This type is commonly referred to as "Jake Brake"
because the predominant manufacturer is Jacobs Vehicle Equipment Co.)
Other types of retarders include exhaust retarders,
transmission-mounted hydraulic retarders and axle-mounted
electromagnetic retarders. RFG (Reformulated Gasoline) Gasoline blended with pollution reducing additives. RoadRailer Semitrailer specially designed to travel both on highway and on rails. Manufactured by Wabash Corp. Rolling Radius Tire
dimension from center of the axle to the ground; measured with tire
loaded to rated capacity. Used in calculating geared speed. RPM (Revolutions Per Minute) Measure of the speed at which a shaft spins. Most often used to describe engine crankshaft speed. Indicated by a tachometer. Runaway Truck Ramp Emergency
area adjacent to a steep downgrade that a heavy truck can steer into
after losing braking power. Usually two or three lanes wide and several
hundred feet long, the ramp is a soft, gravel-filled pathway which
absorbs the truck's forward momentum, bringing it to a safe stop.
Depending on the surrounding terrain, the ramp may be level or run up
or down hill.
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Semitrailer Truck trailer supported at the rear by its own wheels and at the front by a fifth wheel mounted to a tractor or dolly. Setback Axle Front
steering axle moved rearward from the generally accepted standard
position. Advantages: Shorter turning radius and more of a vehicle's
weight shifted to front axle. Shipping Weight "Dry" weight of a truck including all standard equipment, but excluding fuel and coolant. Single-Source Leasing Service
in which companies can lease drivers and trucks from the same source,
rather than having to procure them from different companies. Sleeper Sleeping compartment mounted behind a truck cab, sometimes attached to the cab or even designed to be an integral part of it. Sleeper Team See Team . Sliding Fifth Wheel Fifth
wheel mounted to a mechanism that allows it to be moved back and forth
for the purpose of adjusting the distribution of weight on the
tractor's axles. Also provides the capability to vary vehicle
combination lengths. Sliding Tandem (Slider) Mechanism
that allows a tandem axle suspension to be moved back and forth at the
rear of a semitrailer, for the purpose of adjusting the distribution of
weight between the axles and fifth wheel. Speedability Top
speed a vehicle can attain as determined by engine power, engine
governed speed, gross weight, driveline efficiency, air resistance,
grade and load. Spoke Wheel See Cast Spoke Wheel . Spread Axle (Spread Tandem) Tandem
axle assembly spaced further apart than the standard spacing of 54
inches. The U.S. federal bridge formula favors trailer axles with an
eight or nine foot spread by allowing higher weight than on tandems
with standard spacing. Straight Truck See Truck . SUV Sport/utility vehicle. Synchronized Transmission Transmission
with built-in mechanisms to automatically "equalize" the speed of its
gears to allow smooth shifting without the need to double-clutch.
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Tag Axle See Axle . Tare Weight See Chassis Weight . Tandem Axle (Tandems) Pair of axles and associated suspension usually located close together. (see Spread Axle ) Team (Driver Team) Team of two drivers who alternative driving and resting. TEU (Twenty-Foot Equivalent Unit) Standardized unit for measuring container capacity on ships, railcars, etc. TL (Truckload) The quantity of freight required to fill a trailer; usually more than 10,000 pounds. (see LTL ) TL Carrier Trucking
company which dedicates trailers to a single shipper's cargo, as
opposed to an LTL (Less Than Truckload) carrier which transports the
consolidated cargo of several shippers and makes multiple deliveries.
(see LTL Carrier ) TOFC (Trailer On Flatcar) Method of moving cargo which involves transporting semitrailers on railroad flat cars. (see Piggyback ) Tractor Truck
designed primarily to pull a semitrailer by means of a fifth wheel
mounted over the rear axle(s). Sometimes called a truck tractor or
highway tractor to differentiate from it from a farm tractor. Tractor Trailer Tractor and semitrailer combination. Tri-Axle Truck, tractor or trailer with three axles grouped together at the rear. (see Tridem ) Tridem Group of three axles on a truck, tractor or trailer. Tridems are most common on European semitrailers. Trip Leasing Leasing a company's vehicle to another transportation provider for a single trip. Trip Recorder (On-Board Computer) Cab-mounted
device which electronically or mechanically records data such as truck
speed, engine rpm, idle time and other information useful to trucking
management. Truck Vehicle which carries cargo in a body mounted to its chassis, rather than on a trailer towed by the vehicle. Twins (Twin Trailers) See
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ULEV Ultra-low emissions vehicle. Upper Coupler Load
bearing surface on the underside of the front of a semitrailer. It
rests on the fifth wheel of a tractor or dolly and has a
downward-protruding kingpin which is captured by the locking jaws of
the fifth wheel.
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VIN (Vehicle Identification Number) Assigned by the manufacturer, this number is unique to each vehicle and appears on the vehicle's registration and title. VMRS (Vehicle Maintenance Reporting Standards) Set
of codes developed to facilitate computerized tracking of parts and
labor used in equipment repair. Established and maintained by the
American Trucking Associations. VIOLATION
A breach of rule, law or regulation in which a judicial conviction may, or may not have been imposed.
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Walking Beam Suspension Type
of truck and tractor rear suspension consisting of two beams, one at
each side of the chassis, which pivot in the center and connect at the
front to one axle of a tandem and at the rear to the other axle. WIM (Weigh-In-Motion) Technology for determining a vehicle's weight without requiring it to come to a complete stop.
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Yard Jockey Person who operates a yard tractor. Yard Tractor (Yard Mule) Special tractor used to move trailers around a terminal, warehouse, distribution center, etc.
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