Home / Trucking Glossary
119 terms
A
ABSAnti-lock Braking System helps prevent wheel lockup during hard braking so the driver can maintain steering control.Air BrakeA braking system that uses compressed air to apply the service brakes on many heavy commercial vehicles.Air CompressorAn engine-driven component that supplies compressed air to the vehicle's air-brake system and reservoirs.Air GovernorA control that tells the air compressor when to begin and stop pumping air based on system pressure.Air LineA hose or tube that carries compressed air between brake-system components, including tractor and trailer connections.Air TankA reservoir that stores compressed air for the brake system and other air-operated equipment.Alley DockA backing maneuver in which a commercial vehicle enters a space at an angle, commonly 45 or 90 degrees.AxleA structural assembly that supports vehicle weight and connects wheels at a given position.Axle WeightThe portion of a vehicle's total weight carried by a single axle or axle group.
B
BackingMoving a commercial vehicle in reverse while controlling its path and checking the area around it.Bill of LadingA shipping document describing the freight, shipper, consignee, quantity, and transportation terms.Blind SideThe side of a vehicle with reduced direct visibility, usually the passenger side of a left-hand-drive truck.BobtailOperating a truck tractor without a trailer attached.Brake ChamberA housing that converts air pressure into mechanical force to apply a foundation brake.Brake DrumA rotating cylindrical brake component pressed by brake shoes to create friction and slow the wheel.Brake FadeA reduction in braking effectiveness caused by excessive heat or other brake-system stress.Brake LiningFriction material attached to brake shoes or pads that contacts a drum or rotor.Brake RotorA flat rotating disc squeezed by brake pads in a disc-brake assembly.Breakaway SystemA system designed to apply trailer brakes if the trailer separates from the towing vehicle.Bridge FormulaA federal formula used to determine allowable gross weight based on axle count and spacing.
C
Cab CardA registration credential listing jurisdictions and vehicle information for apportioned operations.Cargo SecurementThe methods and devices used to prevent cargo from shifting, falling, leaking, or escaping.CDLCommercial Driver's License, the state-issued credential required to operate specified commercial motor vehicles.CDL Class AA CDL class generally used for combination vehicles with a qualifying gross combination weight rating and a towed unit over 10,000 pounds GVWR.CDL Class BA CDL class generally used for a single qualifying heavy vehicle and certain smaller towed units.ChassisThe load-bearing vehicle frame and related running components that support a truck body, container, or equipment.ChockA wedge placed against a wheel to help prevent unintended vehicle movement.ClearanceThe available height, width, or space for a commercial vehicle to pass safely.CLPCommercial Learner's Permit, which authorizes supervised practice in the proper class and endorsements subject to applicable rules.CMVCommercial Motor Vehicle, a vehicle that meets an applicable federal or state commercial definition.Combination VehicleA powered vehicle connected to one or more towed units, such as a tractor and semitrailer.ConsigneeThe person or business designated to receive a shipment.Conspicuity TapeReflective material placed on trailers and certain vehicles to improve nighttime visibility.CouplingThe process and system used to connect a tractor to a trailer or another towed unit.Cranking Landing GearRaising or lowering trailer support legs with the landing-gear handle.
D
DAC ReportAn employment-history report used by some motor carriers when evaluating driver applicants.DeadheadOperating a commercial vehicle without revenue freight, often while repositioning for the next load.DEFDiesel Exhaust Fluid, a urea-based fluid used by selective catalytic reduction systems to reduce certain emissions.DispatchThe function that assigns loads, communicates trip details, and coordinates drivers and equipment.Dock LockA device that restrains a trailer at a loading dock to reduce unintended movement or early departure.DollyA converter dolly has an axle, fifth wheel, and drawbar used to connect semitrailers in a multiple-trailer combination.DOT PhysicalA medical examination used to determine whether a driver meets applicable physical qualification standards.Double ClutchingA manual-transmission shifting method that uses the clutch twice during each gear change.Doubles and Triples EndorsementThe T endorsement that authorizes operation of qualifying double or triple trailer combinations when permitted.DowngradeA descending roadway grade that can increase vehicle speed and brake demand.Drive AxleAn axle that receives power from the drivetrain and turns the wheels.Drop and HookAn operation in which a driver drops one trailer and connects to another instead of waiting for live loading.DVIRDriver Vehicle Inspection Report, used to document reportable vehicle defects or deficiencies under applicable rules and carrier procedures.
E
E RestrictionA CDL restriction that prohibits operation of a commercial motor vehicle with a manual transmission when the skills test was completed in an automatic vehicle.ELDElectronic Logging Device, equipment that records driving time and helps create a driver's record of duty status.ELDTEntry-Level Driver Training, the federal training requirements for specified first-time CDL applicants, upgrades, and endorsements.Emergency EquipmentRequired safety items carried on a CMV, such as warning devices and a properly rated fire extinguisher.EndorsementAn authorization added to a CDL for specialized operations such as hazardous materials, passengers, school buses, tank vehicles, or doubles and triples.
F
Fifth WheelThe coupling plate on a tractor or dolly that locks around a trailer kingpin.Fifth-Wheel SlideA mechanism that allows the tractor's fifth wheel to move forward or rearward to adjust axle loading.FlatbedAn open trailer with a level deck used for freight that does not require an enclosed van.FMCSAFederal Motor Carrier Safety Administration, the U.S. DOT agency responsible for regulating and supporting motor-carrier safety.Freight BrokerA person or company that arranges transportation between shippers and authorized motor carriers.
G
GCWRGross Combination Weight Rating, the manufacturer's specified loaded weight rating for a vehicle and its towed units.Glad HandA coupling connector used to join tractor and trailer air-brake lines.GOALGet Out And Look, a backing safety practice used to verify the vehicle's path and clearance.Gross Vehicle WeightThe actual total weight of a vehicle and its cargo, fuel, driver, and equipment at a given time.GVWRGross Vehicle Weight Rating, the manufacturer's maximum loaded weight rating for a single vehicle.
H
HazMatHazardous materials are substances regulated in transportation because they may present health, safety, property, or environmental risks.HazMat EndorsementThe H endorsement authorizes a properly qualified CDL holder to transport placardable hazardous materials.Hours of ServiceFederal or state rules that limit driving and on-duty time and require qualifying rest periods.
I
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K
L
Landing GearRetractable supports at the front of a semitrailer used when the trailer is not attached to a tractor.Lane TrackingMaintaining a commercial vehicle's proper position within a travel lane through curves, turns, and straight roadway segments.Live LoadA shipment loaded while the driver waits with the trailer at the facility.Load BoardA marketplace where freight opportunities are posted for authorized carriers and brokers.Low-Air WarningA visual and audible warning that activates when air-brake system pressure falls below a specified level.
M
N
O
P
P EndorsementThe passenger endorsement authorizes a properly qualified CDL holder to operate certain passenger-carrying vehicles.PayloadThe weight of freight, passengers, or other revenue-producing load carried by a vehicle.Permit BookA physical or electronic collection of vehicle credentials, permits, registration, and supporting documents.PlacardA diamond-shaped hazardous-material warning sign displayed on a transport vehicle when required.Post-Trip InspectionA vehicle condition review performed after operation, with defect reporting as required by applicable rules and carrier policy.Pre-Trip InspectionThe driver's systematic check before operation to be satisfied that the CMV is in safe operating condition.
R
ReeferA refrigerated trailer or truck body used to transport temperature-controlled freight.RODSRecord of Duty Status, the driver's log of off-duty, sleeper-berth, driving, and on-duty-not-driving time.Route SurveyA review of a planned route for clearances, restrictions, permits, turns, grades, and facility access.
S
S EndorsementThe school bus endorsement authorizes a qualified CDL holder to operate a school bus and is used with the passenger endorsement.ScalingWeighing a commercial vehicle to determine gross, axle, or axle-group weights.Service BrakeThe primary brake system used by the driver to slow and stop the vehicle during normal operation.ShipperThe person or business that tenders freight for transportation.Shipping PapersDocuments that describe transported goods and provide required shipment information.Slack AdjusterA brake component that transfers pushrod motion to the foundation brake and maintains or permits adjustment of brake stroke.Sleeper BerthA compliant resting compartment installed behind or beside the driving area of certain commercial vehicles.Sliding TandemsA movable trailer-axle assembly used to adjust weight distribution and trailer wheelbase.SpotterA trained person who helps guide a vehicle maneuver from outside the vehicle.Steer AxleThe front axle that supports the steering wheels and carries part of the vehicle's weight.Straight-Line BackingBacking while keeping the vehicle aligned in a straight path.
T
Tandem AxlesTwo axles positioned close together and treated as an axle group for many weight rules.Tank EndorsementThe N endorsement authorizes operation of certain commercial vehicles transporting liquid or gaseous material in tanks.Team DrivingAn operation in which two qualified drivers share responsibility for moving a truck, often to keep freight moving longer each day.Tire Tread DepthThe measured depth of the main grooves in a tire's tread, subject to minimum standards based on position and use.TorqueRotational force produced by an engine or applied to a fastener.TPRFMCSA's Training Provider Registry, which lists registered ELDT providers and receives training-completion information.Tractor Protection ValveA valve designed to protect the tractor's air supply if the trailer separates or a major trailer air leak occurs.Trailer SwingSideways movement of the rear or body of a trailer during turning or backing.Trip InspectionA general term for systematic vehicle checks before, during, or after a trip.Trip PlanningPreparing a commercial trip by evaluating route, weather, fuel, parking, clearances, appointments, hours, and required documents.Tug TestA low-force test used after coupling to help confirm the trailer is held by the fifth-wheel connection.Turnaround TimeThe total time needed to complete a pickup, delivery, loading, unloading, or equipment exchange.