Trucks and Trailers Industry Terminology

ABS (Antilock Braking System)

An active safety system that prevents wheel lockup under heavy braking, helping maintain steering control and reduce stopping distance. Mandated on most tractors and trailers in North America.

-Trailer ABS fault light came on; schedule service before the next run. -ABS helps the driver maintain control on wet ramps. -All our new trailers are spec’d with ABS and roll stability.

Aerodynamic Devices

Add-ons that reduce air drag on tractors and trailers (e.g., side skirts, rear fairings/trailer tails, nose cones, tandem covers), improving fuel economy and emissions.

-We added side skirts and trailer tails to cut drag and save fuel. -Nose cones and fairings help us meet GHG Phase 2 targets. -SmartWay-verified aero kits improved our mpg by 5%.

Air Ride Suspension

A suspension using air springs (air bags) to cushion the ride, protect cargo, and allow limited ride-height adjustment; common on van and reefer trailers.

-Switching to air ride reduced claims on fragile freight. -Raise the deck height using the air dump valve. -Air bags need inspection for cracks during PM.

APU (Auxiliary Power Unit)

A small diesel or battery-electric system that provides heating, cooling, and electrical power to the cab when parked, reducing engine idling, fuel use, and emissions.

-The APU keeps the cab cool without idling the engine. -APUs help us comply with idling restrictions. -We calculated a 1.5-year payback on diesel APUs.

ATIS (Automatic Tire Inflation System)

A trailer-mounted system that automatically maintains preset tire pressure via air lines routed through the axle, reducing tire wear, blowouts, and fuel use.

-ATIS kept the trailer tires at 100 psi all week. -We saw fewer roadside calls after installing ATIS. -ATIS plus TPMS helps protect casings for retread.

Backhaul

A return load that fills the truck on the way back from a delivery, reducing empty miles and boosting asset utilization.

-We secured a backhaul out of Dallas to avoid deadhead. -Broker found a backhaul at $2.10 per mile. -Backhaul revenue improved fleet utilization.

Bill of Lading (BOL)

A legal document issued by the shipper acknowledging receipt of goods, listing terms and details of the shipment; serves as a contract of carriage and receipt of goods.

-Dispatch needs the BOL number to trace the shipment. -Driver noted damage exceptions on the BOL. -Signed BOL is required to invoice the customer.

Bridge Formula

Federal rule that limits axle weight based on the number of axles and the distance between them to protect bridge infrastructure; affects axle placement and load distribution.

-Slide the tandems to meet the Bridge Formula. -We were legal on gross but over on the bridge. -Know axle spacing to avoid bridge law citations.

CARB Compliance

Conformance with California Air Resources Board regulations covering emissions, idling, transport refrigeration units, and sometimes trailer aerodynamics and tires for certain operations.

-Our reefers must meet CARB TRU requirements. -Spec low-NOx engines for CARB-compliant operations. -Trailer aero and LRR tires help with CARB enforcement.

Converter Dolly

A wheeled unit with an axle and fifth wheel used to connect one semi-trailer to another, enabling doubles or triples combinations.

-Hook the converter dolly to run doubles. -Check the dolly’s fifth wheel and brakes before use. -Dolly pintle and safety chains must be inspected.

CSA Score (Compliance, Safety, Accountability)

FMCSA’s safety measurement system evaluating carriers across BASIC categories (e.g., unsafe driving, HOS, maintenance) based on roadside inspections and crashes.

-Brake violations are hurting our CSA scores. -Better DVIRs improved our Vehicle Maintenance BASIC. -High CSA scores can limit shipper access.

Deadhead

Operating a truck or tractor-trailer with no paying load, typically to reposition for the next shipment.

-We ran 120 miles deadhead to the next pickup. -Reduce deadhead with better network design. -Backhaul strategy cut deadhead by 15%.

DEF (Diesel Exhaust Fluid)

A urea and deionized water solution injected in SCR aftertreatment to reduce NOx emissions in diesel engines.

-Top off DEF before heading into California. -Low DEF quality can trigger engine derate. -DEF usage averages 2–3% of fuel consumption.

Detention Time

Time a driver waits at a shipper or receiver beyond agreed free time; often billable and a key cause of lost productivity.

-Shipper pays $75/hour after two hours detention. -ELD data supports our detention invoices. -Reducing detention improves asset turns.

DPF (Diesel Particulate Filter)

An exhaust aftertreatment component that traps soot particles and periodically regenerates to burn off accumulated material.

-The DPF needs an ash cleaning at 300k miles. -Frequent regens indicate a DPF issue. -High idle can plug the DPF faster.

Drop-and-Hook

Operating model where drivers drop a loaded trailer and hook to a preloaded or empty trailer, reducing loading/unloading delays.

-We run drop-and-hook to cut dwell time. -Yards need enough empties to support drop-and-hook. -Drop-and-hook improves driver productivity.

DVIR (Driver Vehicle Inspection Report)

A required pre-trip/post-trip inspection report documenting vehicle or trailer defects and corrective actions, supporting safety compliance.

-Submit your eDVIR before leaving the yard. -DVIR found a cracked brake chamber. -Missing DVIRs can fail audits.

Dry Van Trailer

An enclosed, non-refrigerated box trailer used for general freight; common length in North America is 53 feet.

-Most consumer goods move in 53' dry vans. -We spec dry vans with logistics posts. -Dry van vs. reefer changes rate and equipment.

ELD (Electronic Logging Device)

A device that electronically records a driver’s hours of service by synchronizing with the vehicle’s engine, replacing paper logs for most carriers.

-ELD mandate changed how we plan HOS. -The ELD flagged a violation risk. -We integrated ELD data into the TMS.

Freight Broker

A licensed intermediary that arranges transportation between shippers and carriers, without owning the equipment; compensated by a fee or margin.

-The broker tendered a load via the load board. -We negotiated the broker’s margin. -Broker credit checks reduce payment risk.

Freight Class (NMFC)

The NMFC system that categorizes LTL freight (classes 50–500) based on density, handling, stowability, and liability to determine pricing.

-The shipment reclassed from 70 to 85. -Use a density calculator to get the right class. -LTL quotes depend heavily on freight class.

FTL (Full Truckload)

A shipment that uses the full capacity of a trailer (by weight or cube) and typically moves direct from origin to destination with no terminal handling.

-It’s an FTL move from Dallas to Atlanta. -FTL rates are strong in the spot market. -Converting LTLs into FTLs reduces cost.

GAWR (Gross Axle Weight Rating)

The maximum distributed weight that may be supported by an axle or axle group as specified by the manufacturer.

-We’re over the GAWR on the tandems. -Spec higher GAWR for heavy commodities. -GAWR limits dictate how we load pallets.

GHG Phase 2

U.S. EPA/NHTSA greenhouse gas and fuel-efficiency standards for medium- and heavy-duty vehicles and certain trailers, phasing in technologies through 2027.

-Trailer aero helps meet GHG Phase 2. -We document compliance for new tractor specs. -LRR tires are part of GHG Phase 2 strategy.

GVWR (Gross Vehicle Weight Rating)

The maximum allowable total weight of a vehicle or trailer when fully loaded, as rated by the manufacturer.

-Don’t exceed the trailer’s GVWR. -Specs list GVWR for the tractor and trailer. -Payload depends on GVWR minus tare.

Hazmat Placarding

Regulated signage placed on vehicles transporting hazardous materials to indicate hazard class and aid in emergency response.

-We need Class 3 placards for this load. -Verify placards are visible and undamaged. -49 CFR rules govern hazmat placarding.

HOS (Hours of Service)

Federal limits on driving and on-duty time designed to prevent fatigue, including daily and weekly limits and required breaks.

-Plan around the 14-hour HOS clock. -The 30-minute break resets the short-haul. -He hit his 70/8 and had to take a reset.

Intermodal

Using multiple transport modes (e.g., rail and truck) in a single move, typically with standardized containers and minimal cargo handling.

-We converted long-haul lanes to intermodal. -Dray carriers handle the ramps. -Domestic 53' intermodal competes with OTR.

Kingpin

The steel pin under the trailer nose that locks into the tractor’s fifth wheel; also a measurement reference for legal axle settings.

-Grease the kingpin to prevent wear. -Check kingpin lock engagement. -Kingpin-to-axle setting affects bridge law.

Landing Gear

Retractable support legs at the front of a semi-trailer that hold it up when uncoupled from the tractor.

-Don’t drop the trailer; lower the landing gear fully. -Lubricate the landing gear jackscrew at PM. -We bent the landing gear on a high hook.

Liftgate

A hydraulic or electric platform mounted at the trailer’s rear to raise or lower freight when docks or forklifts aren’t available.

-This delivery needs a 3,000-lb liftgate. -Battery voltage is low; the liftgate is slow. -Add liftgate service to the accessorials.

Lowboy Trailer

A heavy-haul trailer with a dropped deck (often a removable gooseneck) that carries tall or heavy equipment while keeping overall height low.

-Use a lowboy for the excavator move. -RGN lowboys ease loading heavy equipment. -Low deck height keeps us under the bridge.

LTL (Less-than-Truckload)

Shipments that do not fill a trailer and are consolidated with other freight in a hub-and-spoke terminal network.

-We’ll move that as an LTL shipment. -LTL pricing uses class and FAK rules. -Cross-docking is standard in LTL networks.

MC Number (Motor Carrier Number)

FMCSA-issued operating authority number for for-hire motor carriers and brokers; distinct from the USDOT number.

-Verify the broker’s MC number is active. -Our MC authority is pending. -The shipper requires carriers with valid MCs.

NOx Emissions

Oxides of nitrogen produced during diesel combustion; a major air pollutant targeted by SCR aftertreatment and evolving emission standards.

-Low-NOx engines are coming for 2027. -SCR with DEF reduces NOx. -CARB’s Omnibus targets NOx reductions.

Overdimensional Permit

Authorization to move oversize or overweight loads that exceed statutory limits, specifying routes, times, and escort requirements.

-We need permits for 12-foot-wide loads. -The route requires a night-move permit. -Two pilot cars are mandated by the permit.

Owner-Operator

An independent driver who owns or leases their truck, either leased to a carrier or operating under their own authority.

-She’s an owner-operator leased to our fleet. -Fuel surcharge is critical for owner-operators. -They ran under their own authority as O/Os.

Payload

The weight of the cargo being carried, typically gross vehicle weight minus the empty (tare) weight of the vehicle/trailer.

-Aluminum wheel specs increased payload. -We’re cube-out before we hit payload limits. -Payload equals gross minus tare weight.

PM (Preventive Maintenance)

Scheduled inspections and servicing designed to prevent failures, extend component life, and maintain regulatory compliance.

-The trailer is due for a PM B service. -We aligned PM schedules with DOT annuals. -PM compliance cut roadside breakdowns.

POD (Proof of Delivery)

Documentation (paper or electronic) signed at delivery confirming receipt of goods, used for invoicing and claims resolution.

-Upload the ePOD to trigger billing. -POD shows two cartons short at delivery. -No POD, no payment under our contract.

PTO (Power Take-Off)

A device that transfers engine power to auxiliary equipment (e.g., hydraulic pumps) for vocational applications like dumps, tankers, and blowers.

-Engage the PTO before running the blower. -End dumps need a wet kit with PTO. -Idle speed increases when the PTO is on.

Reefer (Refrigerated Trailer)

An insulated trailer equipped with a transport refrigeration unit (TRU) to maintain a controlled temperature for perishable cargo.

-Pre-cool the reefer to 35°F before loading. -CARB TRU rules affect our reefer fleet. -Download the reefer temp recorder for QA.

Regeneration (DPF)

The process of burning off soot captured in the diesel particulate filter, which can occur passively, actively, or via a driver-initiated parked regen.

-The dash shows an active regen. -Perform a parked regen if the warning persists. -Incomplete regens can cause a derate.

Residual Value

The estimated value of a truck or trailer at the end of its holding period or lease term; a key factor in lifecycle cost.

-Higher residuals lower lease payments. -Spec choices impact residual value at sale. -We hedged residual risk with a TRAC lease.

SCR (Selective Catalytic Reduction)

An exhaust aftertreatment system that injects DEF into the exhaust stream to convert NOx into nitrogen and water.

-SCR needs DEF to function. -We replaced the SCR catalyst under warranty. -SCR helps meet low-NOx standards.

Side Skirts

Panels mounted along the lower sides of a trailer to reduce aerodynamic drag and improve fuel economy.

-Side skirts cut fuel burn by ~4–7%. -Repair the torn skirt from last dock hit. -Skirts are SmartWay-verified on our spec.

Sliding Tandems

A movable trailer axle group that can be repositioned along the trailer to adjust weight distribution and effective wheelbase.

-Slide the tandems forward for city turns. -We moved the tandems to balance weight. -Lock the pins before pulling out.

SmartWay Certification

An EPA program that verifies fuel-saving technologies and recognizes carriers and shippers for freight efficiency and reduced emissions.

-We buy SmartWay-verified tires and aero. -SmartWay carrier status helps in RFPs. -We report SmartWay emissions annually.

Telematics

Onboard hardware and software that collect and transmit data (location, utilization, diagnostics, temperature, door status) for fleet management and analytics.

-Telematics shows trailer location and dwell. -We monitor reefer temps via telematics. -Geofencing automates arrival and departure.

TMS (Transportation Management System)

Software used by shippers, brokers, and carriers to plan, execute, track, and settle freight moves, including tendering, routing, visibility, and analytics.

-The TMS auto-tenders loads to carriers. -We use the TMS for rating and optimization. -AP integrates TMS data for freight audit.