Ad Valorem Tax

A charge levied on persons or organizations based on the value of transaction. It is normally a given percentage of the price of the retail or manufacturing stage and is a common form of sales tax; e.g. Federal excise tax on new trucks and trailers.

ABS (Antilock Braking System)

The 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)

A vehicle powered by a fuel other than gasoline or diesel.

Air Ride Suspension

The 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)

A vehicle designed for any type of terrain.

AVI (Automatic Vehicle Identification)

A system combining an on-board transponder with roadside receivers to automate identification of vehicles. Uses include electronic toll collection and stolen vehicle detection.

AVL (Automated Vehicle Location)

The 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.

Axle

A structural component to which wheels, brakes and suspension are attached.

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.

Backhaul

Refers to a load of freight which permits a trucker to return to his home with a loaded truck, rather than an empty one.

BBC

The distance from a truck's front bumper to the back of its cab.

Billing

The preparation of the freight bill, the primary document for a common carrier shipment including a description of the freight, number of pieces and charges.

Bill of Lading

An itemized list of goods contained in a shipment.

Blind Spot

The areas around a commercial vehicle that are not visible to the driver either through the windshield, side windows or mirrors.

Bobtail

A tractor operating without a trailer. Also refers to straight truck.

Bogie (also spelled bogey)

An assembly of two or more axles, usually a pair in tandem.

Brake Horsepower (bhp)

The engine horsepower rating as determined by brake dynamometer testing. (See Horsepower)

Break Bulk

To separate a composite load into individual shipments and route to different destinations.

Break Bulk Terminal

A terminal designed to act as an intermediate sorting point for interregional freight. Freight from various end-of-line terminals is sent to a regional break bulk terminal to be combined into full trailers that the carrier then routes to a subsequent end-of-line terminals. Example: freight destined for Texas from a Binghamton, NY terminal might go to Stroudsburg, PA to be combined with other freight destined for Texas from other Eastern cities.

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.

Cabover (Cab-Over-Engine, COE)

A truck or tractor design in which the cab sits over the engine on the chassis.

Cargo Weight

The combined weight of all loads, gear and supplies on a vehicle.

Carload

A Single shipment of freight required to fill a rail car.

Cartage Company

A company that provides local (within a town, city or municipality) pick-up and delivery.

Cast Spoke Wheel

A 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 and Disc Wheel)

CB (Citizens Band Radio)

A 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)

A 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)

The distance from back of a truck's cab to the end of its frame.

CFC

Chlorofluorocarbon.

CG (Center of Gravity)

The 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)

The weight of the empty truck, without occupants or load.

Claim

(a) A demand made upon a transportation company for payment, due to loss or damage of freight alleged to have occurred while shipment was in possession of carrier.

(b) A demand upon a transportation company for refund of an overcharges from the erroneous application of rates, weights, and assessment of freight charges.

Class I Motor Carriers

A common or contract motor carriers of property that have average gross operating revenues of $5,000,000 or more annually from motor carrier operations.

Class II Motor Carriers

A common or contract motor carriers of property that have average gross operating revenues of $1,000,000 or more , but under $5,000,000 annually from motor carrier operations.

Class III Motor Carriers

A common or contract motor carriers of property that have average gross operating revenues of less than $1,000,000 annually from motor carrier operations.

Class I Truck

A truck with gross vehicle weight (GVW) of 6,000 lbs or less.

Class II Truck

A truck with gross vehicle weight (GVW) of 6,001-10,000 lbs.

Class III Truck

A truck with gross vehicle weight (GVW) of 10,001-14,000 lbs.

Class IV Truck

A truck with gross vehicle weight (GVW) of 14,001-16,000 lbs.

Class V Truck

A truck with gross vehicle weight (GVW) of 16,001-19,500 lbs.

Class VI Truck

A truck with gross vehicle weight (GVW) of 19,501-26,000 lbs.

Class VII Truck

A truck with gross vehicle weight (GVW) of 26,001-33,000 lbs.

Class VIII Truck

A truck with gross vehicle weight (GVW) of 33,001-10,000 or more lbs.

CNG

Compressed natural gas.

COFC

A container on a (rail) flat car. A form of intermodal movement of freight using a box suitable for use on rail cars, trailer frames, and container ships.

Containers come in many sizes. International containers which are used on ships usually have height and width of eight feet. Length can vary, but 20 and 40 foot lengths are the most common. US domestic containers are generally taller than international containers and may not always be suitable for ocean transportation.

Combination Vehicle

An equipment configuration which includes separate power unit (tractor) and at least one trailer.

Commercial Trailer

A trailer used to handle freight in the transportation of goods for others; excludes house trailers, light farm trailers and car trailers.

Commodity

Any article of commerce. Goods shipped.

Common Carrier

A transportation business that offers service to the general public. Interstate common carriers must hold a franchise issued by the ICC which limits service to a specific geographical area.

Recent changes in regulation have blurred the distinction between common, private, and contract carriers. Term may be meaningless in the near future.

Compensated Intracorporate Hauling

A freight transportation service provided by one company for a sister company.

Competitive Rate

A charge established to meet the competition of another transportation line.

Connecting Carrier

A carrier which interchanges trailers with another for completion of shipments.

Container Chassis

The single-purpose semitrailer designed to carry a shipping container.

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.

Contract Carrier

For hire carriers which proved transportation under specific contracts or agreements that do not fall within the legal boundaries of common carriage. Recent changes in regulation have blurred the distinction between common, private, and contract carriers. This term may be meaningless in the near future.

Cube (Cubic Capacity)

The interior volume of a truck body, semitrailer or trailer, measured in cubic feet.

CWT

Hundred weight, or one hundred pounds.

Dead-Heading

Operating a truck without cargo.

Demountable Rim

A 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

A 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.

Dispatching

The scheduling and control of truck pickup and delivery. A critical link in dispatching process is communication with driver which may be accomplished by phone, pager, radio, satellite communication, and cellular phone.

Displacement (Piston Displacement)

The 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.

Dock

A platform where trucks are loaded and unloaded.

Dolly

An auxiliary axle assembly having a fifth wheel used for purpose of converting a semitrailer to a full trailer. Dollies can be used to haul multiple trailers behind a single power unit. (Also referred to as Bogie)

Domestic Intercity Trucking

Trucking operations within the territory of the United States, including intra-Hawaiian and intra-Alaskan, which carry freight beyond the local areas and commercial zones.

Double

A combination of two trailers pulled by a power unit. Usually refers to a power unit pulling two 28' trailers. See also Rocky Mountain Double and Turnpike Double.

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).

DRL (Daytime Running Lights)

A system that automatically turns on a vehicle's low beam headlights when the parking brake is released and the ignition is on.

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.

End-of-Line Terminal

A terminal used for pick-up and delivery of freight. Freight collected is sorted and routed to other end-of-line terminals or break bulk terminals for eventual delivery. Freight received from other terminals is sorted and allocated to drivers for delivery.

Enroute

On the way.

EV (Electric Vehicle)

a vehicle powered by electric motor(s) rather than by an internal combustion engine. Most common source of electricity is chemical storage batteries.

Exempt Carrier

Motor carriers who are exempt from regulation by the type of commodity hauled (agricultural, newspapers) or the type of service provides (in conjunction with air, local in nature).

Recent changes in regulation have blurred the distinction between common, private, and contract carriers. This term may be meaningless in the near future.

Expenses

The cost of doing business, generally excludes current obligations on long term debt.

Fifth Wheel

A device used to connect a semi-trailer and tractor.

Fixed Tandem

An assembly of two axles and suspension that is attached to the chassis in one place, and cannot be moved fore and aft.

For-Hire Carrier

A company in the business of transporting freight belonging to others.

Freight

Any commodity being transported.

Freight Bill

A document for a common carrier shipment. Gives description of the freight, its weight, amount of charges, taxes, and whether collect or prepaid. Charges paid in advance are called prepaid freight bills. charges collected at the destination are called destination or collect freight bills.

Freight Broker

Any person who sells transportation without actually providing it. Usually refers to agent for TL shipments, matching small shippers with carriers. Freight brokers often do not accept any responsibility for their shipments. (See Freight Forwarder and Shipper's Agent)

Freight Forwarder

An individual or company that accepts less-than-truckload (LTL) or less-than-carload (LCL) shipments from shippers and combines then into carload or truckload lots. Designated as a common carrier under the Interstate Commerce Act. Freight forwarders issue a bill of lading for shipments and accept responsibility for cargo. Sometimes refers to company which fills railroad trains with trailers. (See Broker and Shipper's Agent)

GAWR (Gross Axle Weight Rating)

The 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)

The total weight of a loaded combination vehicle, such as a tractor-semitrailer or truck and full trailer(s).

Geared Speed

The calculated vehicle speed at the engine's governed rpm in each transmission gear, or (commonly) in top gear.

Gear Ratio

A 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.

General Freight Carrier

A carrier which handles a wide variety of commodities in standard trailers. Such carriers can provide truckload or less-than-truckload service.

Grade

The 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

A 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%.

Gross Combination Weight (GCW)

The maximum allowable fully laden weight of a truck and its payload. The most common classification scheme used by manufacturers and by states. (See Gross Vehicle Weight)

GVW (Gross Vehicle Weight)

The maximum allowable fully laden weight of a truck and its payload. The most common classification scheme used by manufacturers and by states.

GVWR (Gross Vehicle Weight Rating)

The total weight a vehicle is rated to carry by the manufacturer, including its own weight and the weight of its load.

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

The 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.

Heavy Duty Truck

Truck with a gross vehicle weight generally in excess of 19,500 pounds (class 6-8). Other minimum weights are used by various laws or government agencies.

HCFC

Hydrochlorofluorocarbon.

Highway User Fee or Tax

A charge levied on persons or organizations based on the use of public roads. Funds collected are usually applied toward highway construction, reconstruction, and maintenance. Examples includes vehicle registration fees, fuel taxes, and weight distance taxes.

Horsepower (hp)

The 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

The tested horsepower of a "bare" engine without fan, water pump, alternator, exhaust system or any other accessories.

Horsepower, SAE Net

The horsepower capability of an engine with full accessories and exhaust system. Test procedures per standards of Society of Automotive Engineers (SAE).

Hours-Of-Service

The U.S. Department of Transportation safety regulations which govern the hours of service of commercial vehicle drivers engaged in interstate trucking operations.

ICC (Interstate Commerce Commission)

The federal body charged with enforcing Acts of Congress affecting interstate commerce. Because of recent changes in regulation, this body may be obsolete.

ICC Authorized or Regulated Motor Carriers

A carrier licensed and regulated by the Interstate Commerce Commission to carry freight. With deregulation, the meaning of this term is historical.

Intercity Trucking

Trucking operations which carry freight beyond the local areas and commercial zones.

Intermodal Transportation

Transportation movement involving more than one mode, e.g. rail-motor, motor-air, or rail-water.

Interline Freight

Freight which moves from point of origin to destination over the lines of two or more transportation companies.

Interstate Commerce Act

An act of Congress regulating the practices, rates, and rules of transportation lines engaged in hauling interstate traffic. Because of changes to regulation, this agency may become obsolete.

Interstate Commerce Commission (ICC)

The federal body charged with enforcing Acts of Congress affecting interstate commerce.

Intrastate Traffic

Traffic having origin, destination, and entire transportation within the same state.

ISTA

Intermodal Surface Transportation Efficiency Act of 1991.

IVHS (Intelligent Vehicle Highway Systems)

A 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:

Advanced Public Transportation Systems (APTS)

Advance Traffic Management Systems (ATMS)

Advance Traveler Information Systems (ATIS)

Advanced Vehicle Control Systems (AVCS)

Commercial Vehicle Operations (CVO)

Jackknife

To place the trailer at a very sharp angle to the tractor.

JIT (Just-In-Time)

The manufacturing system which depends on frequent, small deliveries of parts and supplies to keep on-site inventory to a minimum.

Kingpin (Axle)

The pin around which a steer axle's wheels pivot.

Kingpin (Trailer)

The 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.

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

A company or individual which leases vehicles.

Less Than Truckload (LTL)

A quantity of freight less than that required for the application of a truckload rate. The historical definition for LTL freight is shipments under 10,000 pounds. LTL carriers are carriers which specialize in shipments under 10,000 pounds. However, competition from other freight carriers restricts shipments for most LTL carriers to the range between 300 and 3000 pounds.

Lift Axle

An 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.

Line Haul

The movement of freight between cities, excluding pickup and delivery service.

Load Range (Tires)

A letter code system for the weight carrying capacity of tires.

Logbook

A 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

An open flat-bed trailer with a deck height very low to the ground, used to haul construction equipment or bulky or heavy loads.

LPG

Liquid propane gas.

LTL Motor Carrier

. LTL carriers are carriers which specialize in shipments under 10,000 pounds. However, competition from other freight carriers restricts shipments for most LTL carriers to the range between 300 and 3000 pounds.

LTL (Less Than Truckload)

A quantity of freight less than that required for the application of a truckload rate. The historical definition for LTL freight is shipments under 10,000 pounds. LTL carriers are carriers which specialize in shipments under 10,000 pounds. However, competition from other freight carriers restricts shipments for most LTL carriers to the range between 300 and 3000 pounds.

LTL Carrier

A trucking company which consolidates less-than-truckload cargo for multiple destinations on one vehicle.

Modal Share

The percentage of total freight moved by a particular type of transportation.

Nation's Freight Bill

The amount spent annually on freight transportation by the Nation's shippers; also represents the total revenue of all carriers operating in the Nation. This includes private carriers as well as common and contract carriers. The total bill was around $330 Billion in 1992.

Net Profit Margin

A measure of profitability based on the ratio of net income to total operating revenues.

Non-Regulated Trucking

A carrier which is exempt from economic regulation, e.g.exempt agricultural shipments and private trucking operations.

Recent changes in regulation have blurred the distinction between common, private, and contract carriers. Term may be meaningless in the near future.

Operating expenses

The costs of handling traffic including both direct costs, e.g. driver wages and fuel; and indirect cots, e.g. computer expenses and advertising; but excludes interest expense.

Operating Ratio

A measure of profitability based on operating expenses as a percentage of gross revenues.

Overage

Excess freight over the quantity believed to have been shipped, or more service.

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

A trucker who owns and operates his own truck(s).

P&D

Pickup and delivery.

Payload

The weight of the cargo being hauled.

Peddle Run

A truck route with frequent delivery stops.

Piggyback

The transportation of highway trailers or removable trailer bodies on rail cars specifically equipped for the service. It is essentially a joint carrier movement in which the motor carrier forms a pickup and delivery operations to a rail terminal, as well as a delivery operation at the terminating rail head.

Pigtail

A cable used to transmit electrical power from the tractor to the trailer. So named because it is coiled like a pig's tail.

Pintle Hook

A 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.

Ply Rating (PR)

The relative measure of tire casing strength. (See Load Range)

Point of Origin

The terminal at which freight is received from the shipper.

Power Units

The control and pulling vehicle for trailers or semitrailers.

Private Carrier

A 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, a unit of measurement for tire air pressure, air brake system pressure and turbocharger boost.

PTO (Power Takeoff)

A 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

A short, full trailer (supported by axles front and rear) with an extended tongue.

Pup Trailer

A short semitrailer, usually between 26 and 32 feet long, with a single axle.

Rate

The charge for transporting freight.

Rating

The determination of the correct legal rate for a shipment.

Relay (Relay Driving)

A 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

A refrigerated trailer with insulated walls and a self-powered refrigeration unit. Most commonly used for transporting food.

Regular Common Carrier

Any company authorized to serve the public and to transport general commodities over set routes.

Regulated Motor carrier

A carrier subject to economic by the Interstate Commerce Commission. Recent changes in regulation have made this term obsolete.

Retarder

A 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.

Revenue

Moneys paid to carriers as compensation for the movement of freight.

RFG (Reformulated Gasoline)

A gasoline blended with pollution reducing additives.

RoadRailer

A semitrailer specially designed to travel both on highway and on rails. Manufactured by Wabash Corp.

Rocky Mountain Double

A combination vehicle consisting of a tractor, a 45 to 48 foot semitrailer and a shorter 28 foot semitrailer.

Rolling Radius

The 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)

The measure of the speed at which a shaft spins. Most often used to describe engine crankshaft speed. Indicated by a tachometer.

Runaway Truck Ramp

An 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.

Semitrailer

A truck trailer equipped with one or more axles and constructed so that the front end rests upon a truck tractor.

Setback Axle

The 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.

Shipper's Agent

A company which coordinates all aspects of an intermodal move, hiring drayage at both ends, and providing shippers with a single invoice. (See also Freight Forwarder and Broker)

Shipping Weight

The "dry" weight of a truck including all standard equipment, but excluding fuel and coolant.

SIC Code (Standard Industrial Classification Code)

A classification of establishments by type of activity in which they are engaged; for the purpose of facilitating the collection, tabulation, presentation and analysis of data relating to establishments, e.g. SIC 42 Motor Freight Transportation and Warehousing SIC 421 Trucking, Local and Long distance.

Single-Source Leasing

A service in which companies can lease drivers and trucks from the same source, rather than having to procure them from different companies.

Sleeper

A sleeping compartment mounted behind a truck cab, sometimes attached to the cab or even designed to be an integral part of it.

Sliding Fifth Wheel

A 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)

A 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.

Specialized Carrier

A trucking company franchised to transport articles which, because of size, shape, weight, or other inherent characteristics, require special equipment for lading, unloading or transporting. The regulatory meaning of this term is obsolete, but many carriers continue to specialize because specialty items continue to require special equipment and skills.

Speedability

The top speed a vehicle can attain as determined by engine power, engine governed speed, gross weight, driveline efficiency, air resistance, grade and load.

Spread Axle (Spread Tandem)

A 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.

Standard Industrial Classification (SIC) Code

A classification of establishments by type of activity in which they are engaged; for the purpose of facilitating the collection, tabulation, presentation and analysis of data relating to establishments, e.g. SIC 42 Motor Freight Transportation and Warehousing SIC 421 Trucking, Local and Long distance.

State of Domicile

Companies - The state in which the carrier maintains its headquarters.

Drivers - the state in which a driver resides.

Straight Truck

A vehicle with the cargo body and tractor mounted on the same chassis.

Synchronized Transmission

A transmission with built-in mechanisms to automatically "equalize" the speed of its gears to allow smooth shifting without the need to double-clutch.

Tandem Axle (Tandems)

A pair of axles and associated suspension usually located close together. (see Spread Axle)

Team (Driver Team)

A team of two drivers who alternative driving and resting.

Terminal

A building for the handling and temporary storage of freight pending transfer between locations.

TEU (Twenty-Foot Equivalent Unit)

The standardized unit for measuring container capacity on ships, railcars, etc.

Third Structure Tax

Any tax on road users other than registration fees or fuel taxes. See ton-mile tax and weight-distance tax for examples

TL (Truckload)

(a) Quantity of freight required to fill a truck.

(b) When used in connection with freight rates, the quantity of freight necessary to qualify a shipment for a truckload rate.

(c) Historical definition is a shipment of 10,000 pounds or more.

TL Carrier

A 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

A trailer on (rail) flat car. A form of piggyback movement of freight.

Ton-Mile

The movement of one ton of freight a distance of one mile. Ton-miles are computed by multiplying the weight in tons of each shipment transported by the distance hauled for each movement. Total ton-miles for a carrier are calculated by adding the figure for all movements.

Ton-Mile Tax

A tax calculated by measuring the weight of each truck for each trip. The gross weight is assigned a tax rate which is multiplied by the miles of travel.

Tracer

A request that a carrier locate a shipment to speed its movement or to establish proof of delivery, or a request for an answer to a previously filed claim.

Tractor

A 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 Semitrailer

A combination vehicle consisting of a power unit (tractor) and a semi-trailer.

Trailer

A vehicle designed without motive power, to be drawn by another vehicle.

Tri-Axle

A truck, tractor or trailer with three axles grouped together at the rear. (See Tridem)

Tridem

A 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)

A 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

A motor vehicle designed to carry an entire load. It may consist of a chassis and body; a chassis, cab and body; or it may be of integral construction so that the body and chassis from a single unit.

Truck Tonnage

The weight of freight in tons transported by truck.

Truckload (TL)

(a) Quantity of freight required to fill a truck.

(b) When used in connection with freight rates, the quantity of freight necessary to qualify a shipment for a truckload rate.

(c) Historical definition is a shipment of 10,000 pounds or more.

Turnpike Double

A combination vehicle consisting of a tractor and two trailers of 45 to 48 feet.

Truck

A vehicle which carries cargo in a body mounted to its chassis, rather than on a trailer towed by the vehicle.

Twin Trailer

A short semitrailer (under 29;) designed to be operated as part of a combination vehicle with a tandem trailer of similar length.

ULEV

Ultra-low emissions vehicle.

Upper Coupler

A 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.

Uniform System of Accounts

A code prescribing the reporting procedure and specified accounts for motor carriers described by the ICC.

This accounting system is no longer in use.

Vehicle-Mile

A measurement of the total miles traveled by all vehicles in an area. Generally applies to intercity movements only.

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)

A set of codes developed to facilitate computerized tracking of parts and labor used in equipment repair. Established and maintained by the American Trucking Associations.

Walking Beam Suspension

A 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.

Waybill

Description of goods with a common carrier freight shipment.

Weight-Distance Tax

A tax basing the fee per mile on the registered gross weight of the vehicle. Total tax liability is calculated by multiplying this rate times miles traveled.

WIM (Weigh-In-Motion)

A technology for determining a vehicle's weight without requiring it to come to a complete stop.

Yard Tractor (Yard Mule)

A special tractor used to move trailers around a terminal, warehouse, distribution center, etc.