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Trailer Jargon

Ever been in a meeting, unsure of an industry term your team used but didn't want to ask? Bookmark this page for a growing list of trailer and industry jargon!


ABS (Anti-lock Braking System) – An automated system of braking that uses sensors and solenoid valves that act in concert to coordinate wheel speed and the force applied to braking. It’s beneficial to a driver who may be breaking in adverse weather conditions and allows them to gain control of the truck or vehicle should they need to apply heaving braking pressure in a stressful situation such as slipper roadways.

Air Ride Suspension – A type of suspension system that uses and air cushion via air filled chambers or “bags.” This is in lieu of steel coil springs or leave springs. Air suspension, however, requires compressed air which is supplied to a reservoir tank. The compressed air is what’s supplied to the chamber or airbag and provides greatest dampening of force from turbulence. The same compressed air system that is used in the suspension system may also be used in the braking system.

Backhaul - The process of a transportation vehicle (typically a truck) returning from the original destination point to the point of origin. A backhaul can be with a full or partially loaded trailer.

Bill of Lading - This is a key piece of documentation associated with the cargo transported. It indicates that thee contracted goods to be transported were received. The bill of lading itemizes the cargo being transported. The document is a contract between shipper and carrier and indicates receipt of the cargo. The driver is often the person who signs and thereby acknowledges that they received the cargo, as indicated on the bill of lading, and is responsible to be sure that what they sign is truly what's on the bill of lading and what they are transporting.

Carrier - The mover transporting your household goods.

CAT Scales – These scales are weight scales located at various weight stations that accurately measure the weight of the load being carried. The scales are calibrated regularly and must provide the most accurate measure of load.

Chassis - A trailer-type device with wheels constructed to accommodate containers, which are lifted on and off.

Condition-based Maintenance - Maintenance performed on material or equipment based on an underlying condition caused by continuous wear and operation.

Doubles – A double is a combination of twin trailers. A truck tractor may pull two semitrailers in tandem that are connected via a converter dolly. While the load is greater, and consume more power, the tractor can manage to pull it. Thus, more twice as much cargo may be pulled by one truck tractor, however the operational cost of doing so is not necessarily twice the cost of one trailer. Doubles can often be an economical means of transport, but they do require a truck tractor capable of pulling such a load, and a driver qualified and able to haul such a combination.

Drayage - Transporting of rail or ocean freight by truck to an intermediate or final destination; typically, a charge for pickup/delivery of goods moving short distances (e.g., from marine terminal to warehouse).

Dry Van - A trailer that is not refrigerated and normally enclosed, often carrying dry goods. Geofencing - a method of controlling the flow of transportation and supply chain cargo with the GPS, sometimes RFID technology to create a virtual geographic boundary. Software may be programmed to trigger a response when a mobile device enters or leaves a particular area.

Federal Motor Carrier Safety Administration (FMCSA) - The administration within the U.S Department of Transportation (USDOT) responsible for monitoring and developing safety standards for commercial motor vehicles operating in interstate commerce.

Fifth Wheel - Fifth wheel is is the hooked connection at the trailer’s kingpin. The kingpin is the point at which the trailer and tractor or dolly pivots. A fifth wheel derives its name from the fact that four wheels are ordinarily used for a vehicle to travel and make turns. A fifth wheel performs the function as if it were the fifth wheel that allows the other wheels not to turn, but rests on the tractor or dolly, which is the point of pivot and turning.

Fixed Tandem – Tandem refers to a combination of both two axles with associated suspension, fixed to the trailer chassis and does not move or shift back and forth.

Freight Forwarder - An entity (usually a company) that orchestrates truck transportation of cargo belonging to others, and commissions carriers to provide the actual truck transportation. A freight forwarder assumes responsibility for the cargo from origin to destination and usually takes possession of the cargo at some point during the transportation. Freight forwarders typically assemble and consolidate less-than-truckload shipments into truckload shipments at origin and disassemble and deliver shipments at destination.

GAWR (Gross Axle Weight Rating) - This is the maximum weight, as rated by the axle manufacturer, that an axle is rated to carry. The rating incorporates the weight of the axle and the portion of a vehicle’s weight carried by the axle.

GCW (Gross Combination Weight) - Because truck and trailer transport include so many parts that are detachable and interchangeable, the GCW refers to the total weight of the combined truck tractor and its trailer or trailers.

GVWR (Gross Vehicle Weight Rating) - This is an important rating that refers to the total weight a vehicle is rated to carry by the manufacturer of that vehicle. It considers its own weight and the maximum load it is capable of safely pulling or hauling.

Hazardous Materials - Explosives, compressed gases, flammable liquids and solids, oxidizers, poisons, corrosives and radioactive materials. Many common household items are considered hazardous materials. These include nail polish remover, paints, paint thinners, lighter fluid, gasoline, propane cylinders, and automotive repair and maintenance chemicals.

Hazardous Materials Regulations (HMR) - Federal regulations governing the commercial transportation of hazardous materials. The HMR are contained in the Code of Federal Regulations, Title 49, Subtitle B, Chapter I.

Hazmat – Is a common term that refers to hazardous materials, as classified by the United States Environmental Protection Agency (EPA). Transportation of hazardous materials is regulated by the United States Department of Transportation (USDOT or sometimes just DOT). Because hazardous materials is – as its name implies, hazardous – not just any driver can haul it. A driver is required to have a hazmat endorsement on their commercial driver’s license (CDL). In order to attain such an endorsement, the driver must have special training.

Heavy Duty Truck - A classification of truck with a higher gross vehicle weight exceeding 19,500 lb. Class 6 - 8 trucks are considered heavy duty trucks.

Jackknife – This condition occurs when the tractor is at an extreme angle to the trailer – similar to the position of an opening jackknife or pocketknife. The position may be achieved intentionally, as in jackknife parking, or unintentionally, as in a jackknife accident common when slippery conditions are present.

Less-Than-Containerload/Less-Than-Truckload (LCL/LTL) - A container or trailer loaded with cargo from more than one shipper; loads that do not by themselves meet the container load or truckload requirements.

Liftgate - Hydraulic or electric (or both) equipment on the rear of a truck used to lift, load, and unload heavy cargo. The gate assembly is rated by the gross weight it is capable of lifting.

Low Boy - A trailer with a high-capacity rating and a detachable gooseneck, often used for hauling heavy machinery or equipment.

Piggybacking – This term refers to when a trailer and its load – most often tank or container - are loaded on its chassis and often wheels, onto a railcar and transported to rail heads for further intermodal activity. Then it may be offloaded at another location where a truck will haul it to a specified destination.

Predictive maintenance - A maintenance technique assessing material and equipment, understanding critical points of failure or degradation, and estimating reasonable times to perform maintenance to avoid failure.

Leasing Agreement - In the context of trailers, leasing is for terms longer than renting, with terms that fit the longer time duration. Leasing affords use of the trailer without the burden of ownership and provides flexibility to the user if the need diminishes or ends over time, or if the trailer technology becomes obsolete for the user’s needs.

Reefer Trailer - A refrigerated trailer that is commonly used for perishable goods.

Rental Agreement - In the context of trailers, rental agreements are for shorter durations than leases. Renting provides maximum flexibility to meet the needs of the renter. Renting agreements for trailers are better for shorter term needs or seasonal needs, without a continuous need for the trailer over time.

Radio Frequency Identification (RFID) Tags - Physical devices, mounted on a cargo load that uses radio frequency technology with these tags and tag readers that provides an identity of the cargo.

Safety Audit – This is an event that examines a motor carrier’s operations to provide educational and technical assistance on safety and the operational requirements of the Federal Motor Carrier Safety Regulations (FMCSR) and applicable hazardous material regulations (HMR) and to gather critical safety data. This data is then used to measure the carrier’s safety performance and basic safety management controls.

Semitrailer – A semi-trailer does not have a front axle. It is normally combined with a truck tractor to pull it. This common trailer term most often refers to a combined truck and trailer and uses a “fifth wheel” located on the truck tractor or dolly for turning.

Shipper - The person (customer) whose goods are being moved.

Sliding Tandem – When a tandem (paired) axle suspension may be shifted forward and aft to the rear of a semitrailer so its weight may be distributed between axles. The length between the kingpin at the fifth wheel point at the tandem is thus variable to accommodate a varying cargo load.

Third-party Logistics (3PL) Provider – A 3PL is sometimes part of the supply chain. They support logistics by coordinating the transportation, warehousing, and logistics-related services to buyers or sellers. It is a means of using their specific expertise to manage the supply chain and alleviates the burden from the shipper from coordinating it.

Truckload (TL) – Quantity of freight equals a fully loaded trailer, or at a minimum, the amount required to qualify for a truckload rate. TL at its essence means that a fully loaded trailer transports goods from point A to point B without any additional stops.

Twenty-foot Equivalent Unit (TEU) - The 8-foot by 8-foot by 20-foot intermodal container is used as a basic measure in many statistics and is the standard measure used for containerized cargo.

USDOT Number - An identification number assigned to all interstate commercial carriers regulated by the FMCSA. The number is used to track the safety records associated with a given carrier.


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