Whether you are a new to trucking or you’ve been in the industry for years, it always helps to know your trucking terms. We have compiled a list of the most useful and relevant terms for you. Are we missing something? Let us know here.

Air Brake

A brake which is operated by air. The air brake system on tractors consist of air lines, valves, tanks, and an air compressor.

Air Ride Suspension

Air suspension is a type of vehicle suspension powered by an electric or engine-driven air pump or compressor. This compressor pumps the air into a flexible bellows, usually made from textile-reinforced rubber. The air pressure inflates the bellows, and raises the chassis from the axle.

Air spring system

The system in which the container and plunger are separated by pressurized air. When the container and plunger attempt to squeeze together, the air compresses and produces a spring effect.

Air Tank

A reservoir for storing air for use in the air brake system. Braking would be impossible without an adequate supply of air.


An axle is a structural component to which wheels, brakes, and suspension are all attached.

Back Haul

A return load. Many companies, often ones who haul their own product, take a load from their home location to a certain area the country, then they need to go back to the original location to pick up another similar load. Instead of returning empty, they'll find another load (the "back haul") going back to the original location.

Bill of Lading

Shipping documents or shipping papers for a particular shipment. It contains an itemized list of goods included in the shipment. It also serves as a contract of shipment, and a receipt for the goods.

Blind Spot

The areas around a tractor-trailer which are not visible to the driver through the windows or mirrors.


The tractor operating without a trailer attached.

Balloon Freight

Cargo which takes up a lot of space, but is very light.

Brigde Formula

A bridge protection formula used by the federal and state governments to regulate the amount of weight that can be put on each of a vehicles axles and how far apart the axles must be legally be able to carry a certain weight.

Bulk Freight

Freight that is not in packages or containers, normally hauled in tankers, grain trailers, and sometimes in regular van trailers.


Short for cab-over-engine, designed so that the cab sits over the engine on the chassis.

Cartage Company

A motor carrier that provides local pickup and delivery.

CAT Scales

The most common type of scales at truck stops are CAT scales. These are purported to be the most accurate, and they guarantee the weight reading to be accurate, or else they'll go to court for you and pay the fine.

CB (Citizens Band Radio)

The type of radio that's used by truckers to communicate with each other.

CDL (Commercial drivers License)

The drivers license which authorizes individuals to operate commercial motor vehicles and buses over 26,000 pounds gross vehicle weight.

Check Call

Calling by telephone, or using the Qualcomm system to check in with your company/dispatcher, usually once a day, early in the morning. This informs them of your progress, and any other important information a company may require.

Clearance Lights

The lights on top of the front and rear of the trailer; often referred to as the marker lights.

Clutch brake

The clutch brake is engaged when you push the clutch all the way to the floor. You only do this when you're stopped, and need to get the truck into gear.


A shipping container is a standard sized metal box used to transport freight. It is used in Intermodal Transportation, which utilizes different modes of transportation ship, rail, and highway. International shipping containers are 20 to 40 feet long, and have to conform to International Standards Organization (ISO) standards and are designed to fit in ship's holds.

Converter Dolly

The assembly which connects trailers together, as in a set of double or triple trailers. This assembly is equipped with the fifth wheel for coupling.


Driving a tractor-trailer without cargo, or without paying load.


A safety device that hooks to your trailer's bumper when you're backed to a loading dock. This device is controlled from inside the facility, and it prevents the trailer from being able to move away from the dock, especially considering the safety of the forklift driver and anyone else inside the trailer. See the section on " picking up the load".

Empty Call

The call you make to your dispatcher to inform him that you're unloaded/empty, and need a new load assignment.

Fifth Wheel

The coupling device attached to a tractor or dolly which supports the front of the semitrailer and locks it to the tractor or dolly. The center of the fifth wheel hooks to the trailer's kingpin, at which point the trailer and tractor or dolly pivots.


The cargo you're hauling. The same as product, commodity, load, etc.

Frequent Fueler

Many of the major truck stops have frequent fueler programs or cards which drivers can sign up for. These programs give you credit or cash back for each gallon of fuel you purchase.


A device which limits the maximum speed of a vehicle. Used by a great number of trucking companies who want to save on fuel expenses, and limit accidents.


When the tires lose contact with the road due to excess water.

Interaxle Differential

On tractors with tandem rear axles, the interaxle differential allows each axle to turn independently.

Jake Brake

An engine retarder which helps to slow vehicles, especially on down grades.

Johnson Bar

The trailer hand valve, commonly used to test the brakes after coupling the tractor and trailer. Also known as the trolley valve.


A thick, metal pin located underneath the front of the trailer. This kingpin slides into, and connects with, the locking jaws of the fifth wheel of the tractor or dolly, thereby attaching the tractor/dolly to the trailer.

Load Locks

Long metal bars which retract and expand to fit in place from one side wall of the trailer to the other, thereby holding back, and securing the load (cargo).

Log book

The book in which truck drivers record their trucking activities -- a truck driver's hours of service and duty status for each 24-hour period. Details of maintaining your logbook are covered in a different section.

Low Boy

An open flatbed trailer, where the main body of the trailer is very low to the ground so that it can haul oversize or wide loads; often construction equipment, or other extremely bulky or heavy loads.

LTL (Less-Than-Truckload)

A quantity of freight less than that required for the application of a truckload rate, usually less than 10,000 pounds. These smaller loads are consolidated by an LTL carrier into one vehicle headed for multiple destinations.

MVR Report

A driver’s motor vehicle record, which shows all violations, accidents, etc.

No Touch

A situation in which the driver doesn’t have to load or unload (no touching, or fingerprinting, the load) the cargo.

Opti- Idle

Equipment which starts and shuts down the truck to keep the truck a certain temperature inside, while reducing idling time.


Extra freight which shouldn’t have been shipped.


A truck driver who’s in business for himself; and owns and operates his own truck/s, trailer/s, and/or equipment; an independent contractor.


The wooden base onto which a product is loaded. It has slats on the sides which enable a forklift to move products easily.

Pay Load

The weight of the cargo being hauled.


The term used for the situation in which loaded highway trailers are loaded onto railcars, and taken to railheads. From there, local trucks take the trailers the rest of the way to their destination.


The electrical line supplying electric power from the tractor to the trailer, coiled like a pig’s tail.

PTO (Power Takeoff)

A device used in tractors which transmits tractor engine power to auxiliary equipment.


A satellite tracking device and communication tool that can also be used to monitor speed, braking, idling, and other barometers of a driver’s efficiency.

Relay Driving

In LTL shipments, a driver only takes a load a portion of the way, usually for the duration of one shift (eight to 10 hours). The driver then turns the truck over to another driver to continue the trip.

Rider Policy

The company’s policy regarding allowing passengers in the truck with the driver.

Runaway Truck Ramp

An emergency escape ramp used on steep downgrades for trucks which have lost braking power.


A plastic or metal band (once it’s broken, it cannot be reconnected) placed on the trailer door latch. An intact seal ensures that the trailer doors have not been opened, and the cargo is untouched.


A trailer supported at the rear by its own axles and wheels, and at the front by fifth wheel from a tractor or dolly.

Service Plaza

A rest area found on turnpikes or toll roads. These usually have truck parking, restrooms, vending machines, telephones, and often fast food restaurants.


A sleeping compartment situated behind the tractor’s cab, behind the driver’s seat, or an integral part the cab.

Sliding Tandem

A mechanism that allows a tandem axle suspension to be moved back and forth at the rear of a semi-trailer in order to distribute the weight between axles, and adjust the length between kingpin and tandems.

Sliding Fifth Wheel

A fifth wheel with a sliding mechanism which allows it to be adjusted in order to distribute the weight of the axles, varying the overall vehicle length and weight per axle.

Spread Axle

A tandem axle assembly that has the ability to be spread farther apart than the standard spacing. When the tandems are spread to 8 or 9 feet, each axle is weighed independently, with each allowed up to 20,000 pounds (or 40,000 pounds for the combined tandem weight).

Tandem Axle

A pair of axles grouped closely together; either the drive axles on the tractor or the tandem axles of the trailer.

TL Carrier

A trucking company which usually dedicates trailers to a single shippers cargo, as opposed to an LTL carrier, which often transports the combined cargo of several different shippers.


Any combination of three axles grouped together.


A tractor which carries cargo in a body (van, tank, etc.) which is mounted to its chassis, possibly in addition to a trailer which is towed by the tractor. This is common in truck-trailer combination vehicles which haul fuel, or other liquid.


A truck-trailer combination consists of a truck which holds cargo in its body which is connected to its chassis, and which tows a trailer.

Unified Carrier Registration

A system created in 2005 to streamline the process of registration for commercial carriers engaged in interstate commerce.

Upper Coupler

Part of the connection between the tractor and trailer, it carries weight from the trailer, and houses the kingpin, which connects to the fifth wheel of the tractor.


US Department of Transportation.

Vehicle Miles of Travel (VMT)

A unit to measure vehicle travel made by a private vehicle, such as an automobile, van, pickup truck, or motorcycle.

VIN – Vehicle Identification Number

The manufacturer gives a unique VIN to every vehicle.


A document issued by a carrier that lists important details and instructions pertaining to a particular shipment.

Weigh Station

Official facilities that randomly check commercial vehicles’ weights, and sometimes perform mechanical and log inspections as well.

WIM (Weigh-In-Motion)

The system which allows a vehicle to be weighed while still in motion on the interstate, usually just before coming to a weigh station.

Yard Jockey

A driver who shuttles trailers into and out of loading docks at a factory or distribution center.