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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!


7-Way Connector – The electrical plug on the trailer nose that connects tractor power to the trailer. Each pin in the connector has a unique service purpose.


Anti-Lock Braking System (ABS) – Mandated on trailers since 1998, the ABS automatically releases and reapplies the brakes to help keep wheels from locking and causing a lack of driver control in adverse weather conditions. The central ABS controller includes an electronic controller unit (“ECU”) that monitors wheel rotation speed through sensors and controls the braking system hydraulics.

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.


Annual Inspection – The U.S. Department of Transportation Federal Motor Vehicle Safety Administration (USDOT FMVSA) requires that every semi-trailer be inspected annually. After each annual inspection, an updated FMVSA safety sticker (often archaically referred to as an “FHWA Inspection” sticker) should be applied to the nose of the trailer as a reference for drivers, roadside inspectors and maintenance personnel. Copies of the completed inspection forms and the inspector’s certification should remain on file for requested review by CVSA roadside inspectors and/or audit by FMVSA representatives. Ask your Premier Trailer Leasing representative for more information on annual inspections. (Click here for additional information.)


Anti-Lock Braking System (ABS) – Mandated on trailers since 1998, the ABS automatically releases and reapplies the brakes to help keep wheels from locking and causing a lack of driver control in adverse weather conditions. The central ABS controller includes an electronic controller unit (“ECU”) that monitors wheel rotation speed through sensors and controls the braking system hydraulics.


Articulation – See “Fifth Wheel”


Association of American Railroads (AAR) – The railroad trade association that sets design and testing standards (AKA “M931”) for all trailers and containers that might ever be used on or in North American railroad intermodal service.

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.


Bogie – (AKA, “running gear”) The bogie is the trailer’s sub-assembly that includes the axles, suspension, and brake chambers, all connected to a steel beam frame also known as the “slider box”. The bogie sub-assembly is either welded directly to the body of a “fixed suspension” trailer or placed in a “slide track” under the rear of the trailer where it is held in place to a “slide track” by adjustable locking pins so the bogie can be moved forward or back to accommodate different load and/or operating requirements. Note: A trailer bogie should not be confused with a “bogey” as in a spooky night-time creature, or one shot over par in golf.


Brake Wear - See “Tire and Brake Wear”


Bridge Formula – To protect against excessive pavement wear from overweight vehicles, the U.S. Department of Transportation Federal Highway Administration (USDOT FHWA) has established a complex formula to determine the maximum allowable trailer weight per axle based on the length of the trailer and the number and spacing of the axles. (Click here for additional information.) 


Bottom Rail – A key element in the structural design of a trailer, the bottom rails run the full length of the trailer on both sides from front to rear parallel to the road surface. In a “box trailer” design (e.g. dry van or reefer), the bottom rail is most commonly an aluminum extrusion whose purpose is to connect the floor and wall structures of the 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.


California Air Resources Board (CARB) – Established in 1967 under then-governor Ronald Reagan, CARB sets California’s air quality standards for vehicles, fuels and consumer products. Working in conjunction with national policy set by the United States Environmental Protection Agency (EPA) (see also “Smartway Certification”), CARB has taken a leading role among states in setting stricter emissions and energy efficiency regulations for cars, trucks and trailers. For trailers, this includes requirements for approved aero-dynamic devices (e.g. side skirts, etc.), low rolling resistance tires, and eventual elimination of emissions from trailer refrigeration units (TRUs) by 2035. Many other states are now adopting CARB regulations as their own.

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.


Class 7 or 8 – “Heavy Duty” truck and trailer classifications set by the U.S. Federal Highway Administration (FHWA) and used to categorize models by gross vehicle weight rating (“GVWR”). Class 7 trailers have GVWR ratings of 26,001 – 33,000 lbs. Class 8 is anything above 33,000 lbs. These two classifications include virtually all semi-trailer types 28’ and longer.


Collision Damage Waiver (CDW) – See “Loss Damage Waiver”


Commercial Vehicle Safety Alliance (CVSA) – The non-profit alliance was started in 1980 to improve commercial vehicle safety and enforcement by providing guidance, education and advocacy across the United States, Canada and Mexico. CVSA is composed of federal, state, and local officials (including over 13,000 law enforcement officers) along with industry representatives. In addition to its education and advocacy programs, CVSA performs over 4 million commercial vehicle inspections per year across North America, and in conjunction with the U.S. Federal Motor Vehicle Safety Administration (FMCSA), maintains a database of carrier inspection and safety records based on those inspections. CVSA scores help carriers to become safer, insurance companies to establish risk profiles, and shippers to select reliable, quality carrier partners.


Composite Plate – (See also “plate wall”) The generic name for the side wall material initially developed and introduced to the truck trailer industry in the 1990’s by Wabash National under the brand name “DuraPlate”. Composite plate material generally consists of pre-painted galvanized steel sheets laminated on both sides to a High-Density Polyethylene (HDPE) (e.g., “plastic”) core, although other core materials have been unsuccessfully tried. Connected overlapping of the composite plate sheets to create the sidewalls of a dry van trailer provides a wider inside width compared to the traditional “sheet & post” sidewall construction and eliminates the need for plywood lining. Composite plate was developed as a lower cost and higher durability alternative to solid aluminum plate that had been used previously in some trailer and container applications. Composite plate trailers’ market share has grown to over 70% of all new dry vans. The material is now used in other applications beside trailer sidewalls including door panels, side skirts, and roof sheets.

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


Congear – See “Dolly”


Conspicuity Tape – In 1992, the National Highway Traffic Safety Administration (NHTSA) established regulations requiring the use of conspicuity materials (i.e., retroreflective tape or reflex reflectors) on trailers and the rear of truck tractors. The tape is intended to reduce the incidence of motorists crashing into the sides or rear of trailers at nighttime and under other conditions of reduced visibility. (Click here for more information.)


Consignee – The receiver of the freight sent from the “shipper”.


Containers – (AKA “Intermodal Containers” or “Shipping Containers”) Originally developed in the 1950’s for use in ocean shipping, containers are large, structurally independent, freight carrying boxes that are separable from the container chassis used to move the containers on the highway. Containers are stackable in varying heights depending on the type of container and whether empty or loaded.

Marine Containers – (AKA, “ISO Containers”) Typically 96” wide and 8’0”, 8’6” or 9’6” high, marine containers are mostly 20’, 40’ or 45’ long and, depending on whether loaded or empty, are stackable up to 9-high empty. Standardized maximum gross weight ratings for 20’s and 40’s is 67,200 lbs. and 73,000 lbs. for 45’s.

North American Domestic Containers – (AKA, “Domcons”) Mostly 53’ long by 102” wide by 9’6” high, domestic containers are designed to physically emulate the cargo carrying capacity of a 53’ highway trailer as closely as possible while also allowing for the loaded boxes to be carried two-high on double stack rail cars. Versus a 53’ highway van however, domcons are engineered to be lifted and stacked independently from the landing gear and wheel assemblies on a skeletal “container chassis”. This results in a heavier empty tare weight and lower cubic cargo volume of the combined container and chassis than that of a standard van trailer. This comparative cargo loading disadvantage, however, is more than equalized by low railroad double-stack rates in freight lanes of 600 miles or more.


Container Chassis – Skeletal trailers used to transport containers on the road. Chassis are available in a wide range of sizes and configurations depending on what size and weight container is being moved or whether the chassis is designed for one size container or multiple sizes.


Container Chassis Pools – (AKA, “Neutral Chassis Pools”) Large groups of container chassis in various sizes and configurations that are made available for short term rental to highway “drayage” carriers at major rail and port intermodal terminals.


Converter Dolly – See “Dolly”


Corner Radius – The vertical corner piece that connects the nose wall of the trailer to the side wall. Corner radiuses are typically rounded or flat on a diagonal depending on the brand and design of the trailer.


Crashplate – A steel plate at the rear 12 – 48” of the trailer floor that is designed to absorb the heavy impact of a forklift entering the trailer from the loading dock. Depending on the design of the trailer, the crashplate may be overlaid on the trailer’s wood floor or independently engineered directly to the rear crossmembers with no wood underneath.


Crossmember – Either “I” beam or channel shaped, crossmembers are generally steel or aluminum and support the trailer floor latitudinally between the longitudinal “bottom rails” on each side of the trailer. In a dry van or reefer style trailer the crossmembers are connected to the bottom rails using a “crossmember clip” welded to the end of the crossmember and mechanically fastened to the bottom rail.


Dock Leveler – A steel plate hinged to the floor of the loading dock that is used to help equalize the height transition between the dock height and trailer floor height


Dolly – (AKA “Congear”, “Converter Dolly”) A vehicle used to connect trailers together behind a truck tractor in a double or triple trailer LCV (“Longer Combination Vehicle”) configuration. Single axle dollies are most common due to their prevalent use by LTL carriers with 28’ pup trailers, but 2-axle (AKA “tandem axle”) dollies are needed to connect 48’ or 53’ “turnpike doubles”. Key parts of a converter dolly include the “drawbar eye” (the steel ring that connects to the lead trailer’s “pintle hook”), the “fifth wheel” (the hitch plate that connects to the trailer being pulled), the “anti-tip leg” (the retractable front leg used to stabilize and move the dolly when not connected), and, of course, the frame, axles, wheels, tires air & electrical, etc.


Dolly Legs – Archaic for “Landing Gear”


Domestic Containers (Domcons) – See “Containers”


DOT Minimum T&B – (AKA, U.S. Department of Transportation minimum tire and brake depths) The U.S. DOT sets minimum tire tread depth and brake lining thickness, below which vehicle operation is regarded as unsafe and inspection violations will be issued. The minimum DOT trailer tire tread depth is 2/32” and the minimum brake lining thickness is 1/8”. Generally, tires and brakes should be inspected frequently and replaced well before the DOT minimum is reached for reasons of safety and lower cost scheduled maintenance. (Note: other conditions like “flat spotting”, tire side wall damage, and/or cracked brake linings are required by DOT for replacement even if tread depth and lining thicknesses are above DOT minimums.) (See also “Tire and Brake Wear” regarding rental and lease requirements.)

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 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.


Drawbar Eye – See “Dolly”


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. 


Duraplate – See “Composite Plate”


Electronic Stability Control (ESC) – A modern evolution of anti-lock braking systems (“ABS”), ESC is an optional that adds gyroscopic sensing to the steering axle’s directional sensor. When an anomaly conflicts between the two the “ECU” (See Electronic Stability Unit”) intervenes to brake the specific wheels needed to restore stability. ESC is an expensive option and consequently, most often limited to hazmat and tanker applications.


Fairings – See “Side Skirts”


Federal Highway Administration (FHWA)Established in 1966, the FHWA is an agency within the U.S. Department of Transportation that supports state and local governments in the design, construction, and maintenance of the United States highway system.

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 - Refers to the mechanism on the rear of the tractor that connects to the kingpin of the trailer creating a complete tractor trailer configuration. The 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. The combination or two or more vehicles in this manner is called “articulation”.


Finance Lease – (Sometimes also called a “Capital Lease”) The finance company (lessor) maintains legal ownership of the trailer until the end of the agreed lease term when the title passes to the lessee. During the term of the lease, the lessee accounts for the trailer on the books as the owner and in accordance with US GAAP accounting conditions.

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.


Flat Spotting – The wearing down or elimination of tire tread when the trailer is pulled while the brakes are locked. Severe flat spotting requires tire replacement for safety purposes.


Floors – Trailer floors vary in both the material used and the design profile depending on the type of trailer. Dry van trailers typically use laminated hardwood planks fastened side by side longitudinally to the trailer crossmembers. Reefer trailers are generally equipped with either corrugated (AKA “duct”) or flat aluminum floors. Duct floors allow for improved air flow and temperature control throughout the trailer and flat floors allow for the loading and unloading of carts and dollies with caster wheels.


Food Safety Modernization Act (FSMA) – Signed into law in 2011, the FSMA seeks to protect public health more effectively by strengthening the food safety system.  FSMA focuses on preventing food safety problems before they occur including the development and dissemination of guidelines for food handling and transportation.


Full Maintenance Lease – A rental or lease contract that specifies a comprehensive list of maintenance functions to be provided to the lessee by the lessor throughout the duration of the rental or lease term.

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.


Galvanic Corrosion – When dissimilar metals (e.g. steel and aluminum) come in contact with each other and an “electrolyte” (e.g. water) is introduced, an electrical charge is passed between the metals (AKA “Electrolysis”) that corrodes either or both materials to a point of structural degradation and failure. This is particularly key when steel trailer sub-assemblies like upper couplers, crossmembers and rear frames are connected to aluminum parts like top and bottom rails. Galvanic corrosion in these areas can be prevented by connecting similar materials, “Galvanizing” the steel parts, or separating dissimilar materials using a lubricant or non-conductive material like plastic tape or HDPE pads.


Glad Hands – The coupling devices on the air lines of the truck tractor and the front of the trailer that connects and regulates brake line air pressure between the truck tractor and the trailer to allow safe and uniform stopping. (See also “Nose Box”)

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.

Geofencing - An option with many trailer tracking services, “Geofencing” allows for the system administrator to define permissible geo-graphic limits for each specific trailer or group of trailers and to then request a management alert if the defined trailers stray beyond their limits.


GPS Trailer Tracking – The Global Positioning System (“GPS”) is a satellite navigation system owned and operated by the U.S. Government. It provides geolocating and time information to GPS receivers anywhere in the world. Depending on the brand selected, commercial trailer tracking products may use GPS and/or telephonic cellular systems to triangulate the latitude and longitude of trailers equipped with mobile transponders. Most trailer tracking systems are accurate to within 10 – 30’ of the actual trailer location. Powering the on-board transponders depends on the product selected and includes battery, 7-way tractor supply and/or solar. A variety of optional monitoring features for other trailer functions are also available with most trailer tracking brands including Geofencing, interior temperature and cargo sensing, and door open/closed.

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.


Gross Vehicle Weight (GVW) – The trailer’s GVW includes both the empty trailer (see “tare weight”) and everything on it or in it (e.g., cargo). Monitoring loaded trailer GVW is key because excess loading can result in highway inspection violations and/or structural failure accidents from exceeding the engineered Gross Vehicle Weight Rating (“GVWR”) of the trailer. The U.S. federal GVW maximum for most loaded tractor/trailer configurations is 80,000 lbs. on interstates and primary highways. GVW per axle is also regulated and varies based on the axle location in the configuration. (See “Bridge Formula”) Allowable tractor/trailer GVW limits are subject to wide variation on intrastate and local highways not otherwise defined as federal highways.

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.


High Base Rail – Instead of using “scuff” on the lower 12-24” of the interior trailer side walls to help deflect expensive forklift blade damage on the side wall structure, some trailer designs feature an exposed, taller and thicker, heavy duty aluminum bottom rail to take the brunt of the wear. This occurs in specialty composite wall dry van trailer models.


ICC Bumper – Archaic for “Rear Impact Guard (RIG)”


Insulated Vans – Some van trailers are insulated to provide for enhanced temperature or humidity control and may or may not have mechanical refrigeration or heater units. The most common style of insulated vans are sheet and post construction with various kinds of insulation material (e.g., foam block, fiberglass, or spray foam) inserted in the voids between the outer side skin and interior lining of the side walls, nose and roof. Use of non-metal composite materials (e.g., plastic inner and outer skins with foam cores) in lieu of traditional sidewall construction are starting to be introduced into van trailer design.


Insurance – See “Loss Damage Waiver”


Intermodal – Moving freight between two or more transportation modes. Commonly, the term “intermodal transportation” is a reference to the movement of marine and/or domestic containers between trucks, trains and ships.


ISO – The International Organization for Standardization (“ISO”) is based in Geneva Switzerland and is composed of representatives from national standards organizations around the world. The organization develops and publishes over 24 thousand international standards in all technical and nontechnical fields except electrical and electronic engineering, including manufactured products, technology, food safety, agriculture and health care. For semi-trailers, ISO design and manufacturing standards apply to a variety of components and construction materials. Intermodal marine containers are also subject to ISO design and testing requirements.

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.


Kingpin – The kingpin is the key component of the trailer’s “upper coupler” sub-assembly. It connects to the tractor’s fifth wheel to provide the articulated tractor/trailer combination. The kingpin is made of forged steel carefully hardened to precise standards and when properly welded into the all-steel upper coupler assembly it meets or exceeds all the testing and safety requirements set by the AAR, SAE and TTMA.


Landing Gear – (Also “Dolly Legs” – archaic) The retractable legs near the front of the trailer and behind the upper coupler assembly. Used for holding up the nose of the trailer when not connected to a tractor power unit. Key parts of the landing gear assembly include the crank handle and gear box, and the “sandshoe” feet which are generally 10” x 10” steel pads that pivot on the bottom of each leg and distribute the weight of the trailer without sinking into the ground. (In lieu of sand shoes, steel wheels were often used on the bottom of dolly legs in the early days of trucking.)


Less-Than-Truckload (LTL) – Versus truckload (TL) or package, the LTL segment of the trucking industry specializes in moving mid-sized shipments between 150 and 15,000 pounds including palletized or irregular size cargo. Unlike TL, LTL operations are generally organized on a hub and spoke system… picking up “shipper” freight locally, sorting it by destination at nearby regional “cross-dock” hub terminals, trucking the sorted loads “line haul” to regional cross dock hub terminals close to destination, re-sorting again and completing final delivery to the designated local “consignee”. Unlike TL (but like package) the LTL segment requires a regional or national infrastructure of terminals and a wide array of handling and line haul equipment. 28’ “pup” trailers are widely used in LTL for the convenience of their shorter length for local pick-ups and deliveries, and their versatility for terminal-to-terminal line haul moves in doubles or triples configurations. 40’ – 48’ midsized trailer with liftgates is often used for pickup and delivery of heavier shipments. In addition to 28’ doubles and triples combinations, 53’ vans are used in mor cargo dense terminal to terminal lanes. 53’ domestic containers are increasingly used for hub to hub moves in major rail intermodal corridors of 600 miles or more.


Lease – (AKA “Long Term Lease”) A lease is an agreement between the owner of the trailer (“Lessor”) and the carrier who wishes to use the lessor’s trailer (“Lessee”). Technically, the term “lease” refers to a written contract covering the agreement but is also often used to refer to the length of the term of the agreement versus a rental. In that context, “lease” (or “long term lease”) is generally accepted as an agreement of one year or more in duration versus a “rental” which is a lease for less than one year. Other uses of the word “lease” have additional specific meanings that can be confusing. For example, see “Full Maintenance Lease”, “Lease Purchase”, “Finance Lease”, or “TRAC Lease”. Further complicating a clear definition for the word lease are the differing characteristics of a “Net Lease”, or “Triple Net Lease” also defined herein.


Lease Purchase – A lease agreement with a fixed term and an option for the lessee to purchase at the end of the term. The lessor/owner retains the trailer title until the purchase option is exercised.


Lessee – The party that rents or leases the trailer from the owner (“lessor”)


Lessor – The party that owns the trailer and rents or leases it to the lessee.

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.


Line Haul – The movement of freight between two points. More typically, line haul refers to more cargo dense full truck lanes, so in TL that means origination to destination and in LTL it means between hub terminals.


Log Posts – Short for “Logistics Posts”. Vertical trailer sidewall posts in “sheet & post” style trailers that have “slots” to anchor load control beams across the width of the interior. The load beams (Also called “logistics beams” or “shoring beams”) can be used for securing or decking the cargo. Logistics straps can also be used with log posts instead of load beams.


Logistic Seams – In a post-less style composite plate wall trailer, the composite plate panels are sometimes overlapped in such a way as to allow the interior lining material to be slotted to accommodate logistics load bars or straps. While this replicates an independent steel log post, the thinner gauge of the plate wall lining material cannot carry the same load as a typical log post. Furthermore, the 48” width of a standard composite panel does not allow for the more suitable 12”, 16” or 24” log post spacing normally preferred in a sheet and post trailer design.


Logistics Track – Slotted steel or aluminum rails that are install horizontally on both interior sidewalls of a trailer to allow for the installation of load bars or logistics straps to help hold freight cargo in place during transit. There are several styles of logistics track available depending on the carrier application, the material and finish of the rails, and carrier preference for the size and shape of the slots. The most common “e-track” or “a- track” styles feature rectangular slots while some others use round holes.


Longer Combination Vehicle (LCV) – Any of a variety of tractor trailer configurations that includes more than one trailer. In 1991, the Federal Intermodal Surface Transportation Efficiency Act (ISTEA) instituted a freeze on the expanded use of all LCV configurations used at that time on U.S. interstate and primary highways. That freeze continues today. Individual states, however, can and have changed LCV regulations on intrastate roadways adding a wide range of semi-trailer size and weight allowances depending on the jurisdiction.


Loss Damage Waiver (LDW) – Also sometimes referred to as a “collision damage waiver” (CDW). Typically, the trailer “lessor” requires that the “lessee” independently provide insurance for collision, fire, loss or theft of their leased trailers for the duration of the rental or lease term. Proof of this insurance is generally provided to the lessor in the form of an insurance certificate issued by the lessee’s insurer and automatically updated or voided annually at the end of the current policy period. In some instances, large, financially substantial companies will elect to “self-insure” which requires higher credit approval standards and additional lease documentation. LDW or CDW options offered by some lessors at an additional cost to the lessee can substitute or replace the insurance requirements of the lease or rental agreement.

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


Loss Damage Waiver (LDW) – Also sometimes referred to as a “collision damage waiver” (CDW). Typically, the trailer “lessor” requires that the “lessee” independently provide insurance for collision, fire, loss or theft of their leased trailers for the duration of the rental or lease term. Proof of this insurance is generally provided to the lessor in the form of an insurance certificate issued by the lessee’s insurer and automatically updated or voided annually at the end of the current policy period. In some instances, large, financially substantial companies will elect to “self-insure” which requires higher credit approval standards and additional lease documentation. LDW or CDW options offered by some lessors at an additional cost to the lessee can substitute or replace the insurance requirements of the lease or rental agreement.

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.


Marine Containers – See “Containers”


Master Lease – A master lease is a special contractual agreement between the lessor and lessee that encompasses the terms and conditions of all trailer rental and leasing by the lessee for a specified term. Master leases are often preferred by large carriers with significant rental and lease activity to minimize the lease documentation burden for individual transactions. Master lease terms and conditions can vary significantly from the lessor’s standard lease agreement and usually require lengthy legal negotiation between the parties.


Mileage Charge – See “Tire and Brake Wear”


Model Year – Like most vehicles in the automotive industry, a trailer’s model year is the year following the actual manufacturing calendar date for the trailer. The change over for model year varies by OEM, but generally advances from one year to the next in January of the current production year. For example: a trailer built in January of 2022 by one manufacturer whose model year changeover is on January 1 would be given a 2023 model year designation.


Monocoque Design – A modern trailer engineering system taken from aerospace design that uses a “skeletal rib” system created by trailer floor crossmembers, steel sidewall posts, and roof bows surrounded by an outside “skin” (e.g. the trailer floor, sidewall sheets and roof sheet) to produce sufficient independent structural integrity for the standard trailer to carry up to 50,000 pounds of evenly distributed cargo without the support of heavy duty beams under the length of the trailer as required on flatbed trailers. (AKA “frameless construction”) Originally implemented in the 1940’s and 50’ with aluminum sheet and post trailers, the concept remains the same for more recent post-less composite plate wall construction because the overall distributed structural integrity of the composite plate material is enough to replace the need for steel posts.


Multi-Temp – A refrigerated trailer that is designed to accommodate different cargo temperature zones by creating separate compartments inside the trailer and using a specially equipped trailer refrigeration unit (“TRU”). Multi-temp trailers are common in grocery and food service distribution as they can carry a combination of frozen foods, produce and/or dry goods in one trailer load. Multi-temp reefers often have one or more side doors to provide access to the separate temperature zone compartments.


National Highway Traffic Safety Administration (NHTSA) – Originally established by Congress in 1970 as a separate agency within the U.S Department of Transportation (“DOT”), NHTSA is charged with (among other things) writing and enforcing commercial truck and bus industry safety standards (“Federal Vehicle Safety Standards – FMVSS”) as set by the Federal Motor Vehicle Safety Administration (“FMVSA). NHTSA is also responsible for licensing vehicle manufacturers and administering “VIN” (“Vehicle Identification Numbers”)


Net Lease – A lease agreement where the lessee pays a portion of the trailer expenses in addition to the monthly rental payments. Most trailer rental and long-term lease agreements are “net leases” and typically place the responsibility for maintenance, inspections, insurance, taxes, fees and permits with the lessee while titling, licensing and registration remain with the lessor. Net leases are differentiated from “standard maintenance” leases that include maintenance and some other items paid by the lessor. With “triple net leases” the lessee pays for all costs including titling, licensing and registration. Triple net is uncommon in the trailer rental and lease space.


Nose Box – A common name for the location of the air and 7-way electrical connectors on the nose of the trailer. Nose boxes can be either surface mounted on or recess mounted in the trailer front wall, either centered on the nose or off-set on the roadside depending on design of the trailer and customer preference.


Original Equipment Manufacturer (OEM) – The company that builds or assembles the finished trailer for the customer. North American trailer OEMs are technically assemblers for the most part as many of the trailer sub-assemblies are provided assembled by component suppliers.


Package Carriers – The segment of the trucking industry that focuses on moving small, “package” shipments. (AKA UPS and FedEx).


Pintle Hook – The “pincer-type” device permanently installed on the rear of a lead trailer in an LCV configuration allowing for the connection to the drawbar eye of an intermediary converter dolly. The following trailer then connects to the dolly fifth wheel.


Plate Wall – Originally the name for solid ¼” thick aluminum plate trailer and container sidewalls. Plate trailers are now conventionally made of “composite plate” material for their improved structural integrity instead of aluminum.


Pre-Trip Inspection – Physical or computer sensor-assisted check for the proper working order of primary trailer safety features before leaving the yard. (e.g., lights, brakes, tires, air system, etc.)


Pups – 28’ van and reefer trailers used for first and last mile pick-up and delivery and used in doubles or triples LCV configurations for line haul moves.


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.


Rear Impact Guard (RIG) – Historically referred to as the “ICC bumper” or just “the bumper”, the RIG is the structure on the rear of the trailer with the primary purpose of preventing or reducing serious injury to automobile passengers during impact and/or an underride collision with the trailer.


Reefer – Trailer and trucking industry short name for “refrigerated trailer”. Many types and sizes of reefer trailers are common depending on the carrier segment and cargo application. The most common, and the only configuration available for rental or lease is a 53’ single temp, swing door reefer. Other variations do not have the universal demand to justify inventorying in a non-specialized rental/lease fleet.

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.


Running Gear – See “Bogie”

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.


Sandshoes – See “Landing Gear”


Scuff – The additional layer of interior sidewall trailer lining typically measuring 12” – 24” high from the trailer floor that helps to deflect and/or prevent damage from loading and un-loading by the tines of forklift trucks. Carrier scuff preferences vary widely and include corrugated or plate steel, laminated hardwood, and various plastic composite materials.

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.


Sheet & Post – A van sidewall construction that that includes steel posts riveted to aluminum or steel exterior side sheets, and the plywood or plastic lining connected to the posts on the interior. This compares to a plate van for which the plates (aluminum or composite) connect directly to each other to form the structural side wall without posts or lining. The sheet & post design provides a cavity between the outer skin and inner lining that can be filled with insulation if desired. In addition, a sheet and post van usually weigh less than a comparable plate van and is generally better suited to modification with side doors and other special features. Exterior post sheet & post vans have the aluminum posts on the outside. This style of construction is less popular today due to increased aerodynamic drag.


Shipper – The company or person that is sending the freight to the receiving consignee.


Single Temp – A refrigerated trailer (“reefer”) equipped with a trailer refrigeration unit (“TRU”) that is design to cool the entire trailer interior to one consistent temperature. (Versus “multi-temp”)


Side Skirts – Aerodynamic “fairings” installed along the bottom rails of the trailer to reduce drag created by airflow under the trailer. Data shows that side skirts may improve fuel economy up to 4-7% at sustained speeds of 50 MPH or more.


Slide Track – “L” rails welded longitudinally to the trailer crossmembers and parallel to each other at the rear of the trailer. Round holes punched at regular intervals on the vertical section of the “L” track serve as securement points for retractable pins on the “bogie” frame. When the pins are retracted and the trailer brakes applied, the driver can move the tractor and trailer forward or back to reposition the bogie as may be needed for various operating conditions.


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.


SmartWay Certification - Launched in 2002 by the U.S. Department of Environmental Protection (EPA), Smartway is a voluntary public-private program dedicated to researching, tracking, documenting and sharing information about freight equipment fuel use and emissions. Equipment manufacturers, carriers, logistics companies and other transportation companies can participate as “Smartway Certified” partners by following Smartway recommended practices to reduce their environmental footprint.


Society of Automotive Engineers (SAE) – A globally active professional association and standards developing organization for engineering professionals in various industries.


Spring Ride Suspension – Trailer axles mounted below arched steel springs to improve ride quality and add vehicle stability. (Compared to “air ride”.)


Standard Maintenance Lease – A rental or lease contract that specifies a comprehensive list of maintenance functions to be provided to the lessee by the lessor throughout the duration of the rental or lease term.


Tandem Axle – Two-axle running gears (“bogies”) commonly found on longer vans and reefers and most often set in “slide tracks” to allow for re-positioning based on the distributed cargo weight and road conditions. By contrast, 28’ “pup” trailers are conventionally single axle configurations that are fixed at the rear of the trailer.


Tare Weight – The empty weight of the trailer only without cargo.

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.


Tire and Brake Wear (Also “T&B wear”) – Tires and brakes constitute the largest daily operating expenses for most trailers. Those expenses are variable and directly related to the miles operated, road conditions, and maintenance care by the lessee. Given the wide range of lessee operating circumstances, trailer lessors will typically separately charge for tire tread and brake lining wear used by the lessee and in addition to the fixed monthly rental or lease payment. Some lessors charge per 1/32” of tire tread per tire and 1/8” of brake lining per wheel end for wear used between outbound and return inspection measurements taken at the at the lessor’s yard. Some charge a T&B mileage rate based on outbound and inbound hubodometer readings. Others charge estimated mileage in advance that they reconcile upon return of the trailer at the of the rental period.


Tire Pressure Monitoring System (TPMS) - Proper tire inflation pressure is critical to efficient and safe operation of a trailer. Correct tire inflation reduces tire wear, increases fuel efficiency, and leads to fewer roadside breakdowns due to tire failures. Tire pressure monitoring systems (TMPS) monitor pressure and, in some cases, temperature, for each individual tire using various sensor locations and warning methods. In most cases the system will transmit the collected data and display it to the operator and/or fleet. The TPMS monitors each tire based on a pre-set target pressure, and issues alerts based on the difference between the target pressure and the actual measured pressure in the tire.


Top Rail – A key element in the structural design of a trailers, the top rail runs the full length of the trailer from front to rear parallel to the road surface. In a “box trailer” design (e.g. dry van or reefer), the top rail is most commonly an aluminum extrusion that connects the floor and wall structures of the trailer.


TRAC Lease - A Terminal Rate Adjustment Clause (“TRAC”) lease is a fixed term contract between the lessor and lessee that includes a fixed purchase option price at the end of the lease term. With a TRAC lease, If the lessee chooses not to exercise the end-of-lease purchase option they are responsible for any shortfall the lessor may have between the ultimate sale price of the trailer and the originally documented residual purchase price. When appropriate, TRAC leases have tax advantages that can reduce the monthly lease payment to the lessee, but they also have higher credit standards for financing qualification.


Trailer Tracking – See “GPS Trailer Tracking”


Transport (and/or Trailer/Truck) Refrigeration Unit (TRU) – The mechanical unit mounted on the nose of a trailer to provide cooling or heating for temperature sensitive cargo. ThermoKing and Carrier are the primary brand names for North American trailer TRUs.


Transportation Management System (TMS) – Any of a number of software systems (off-the-shelf, customized, or hybrid) that help companies coordinate and manage trucking and logistics operations.

Triple Net Lease – See “Net Lease”


Triples – Three trailers connected to a single tractor for over-the-road operation. Normally, triples refer to the combination of three 28’ “pup” trailers in specific lanes allowed by law.


Truckload (TL) – The segment of the trucking industry that focuses on full trailer loads moved from the originating shipper to the destination consignee. Compare to less-than-truckload (LTL) or package carriers.


Truck Trailer Manufacturers’ Association (TTMA) – The industry trade and lobbying association for North American semi-trailer OEM.s.


Turnpike Doubles – Typically refers to twin 48’ trailer LCV combinations operating on select turnpikes and interstates in the U.S. See “Longer Combination Vehicle”.

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.


Upper Coupler – The trailer steel sub-assembly in the front floor of the trailer that includes the trailer kingpin. The “pick-up plate” of the upper coupler is the smooth steel surface at the bottom/front of the upper coupler that allows the tractor fifth wheel to slide into connection with the kingpin.

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.


Vehicle Identification Number (VIN) – The U.S. NHTSA' requires that each motor trailer must be assigned a unique vehicle identification number (“VIN”), which is a 17-character number that encodes specific information about the trailer’s model year, size, type, original manufacturer, and production series number. The VIN must be prominently displayed on the nose of the trailer and repeated in a hidden location elsewhere on the trailer.


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