• A
  • ABS (Antilock Braking System)

    Computer, sensors and solenoid valves which together monitor wheel speed and modulate braking force if wheel lockup is sensed during braking. Helps the driver retain control of the vehicle during heavy braking on slippery roads.

  • Aerodynamics Package

    A group of components consisting of the following: roof mount wind deflector, side fairings, front spoiler and fuel tank skirting. Also see individual listing for each item.

  • After Cooler

    A performance device found on diesel engines.

  • AFV (Alternative Fueled Vehicle)

    Vehicle powered by a fuel other than gasoline or diesel.

  • Air Brake

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

  • Air Brake Dryer

    A device that removes moisture from air-operated brake systems.

  • Air Foil/Wind Deflector

    Aerodynamic aid attached to the roof of a truck, or tractor creating an air stream over the trailer.

  • Air Ride Suspension/Air Bags

    Suspension which supports the load on air-filled rubber bags rather than steel springs. Compressed air is supplied by the same engine-driven air compressor and reservoir tanks which provide air to the air brake system.

  • 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 affect.

  • Air Tank

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

  • Anteater

    A generic description of a low profile, high aerodynamic tractor.

  • ATC (Automatic Traction Control)

    Usually an optional feature based on ABS, it prevents spinning of the drive wheels under power on slippery surfaces by braking individual wheels and/or reducing engine throttle.

  • Attic

    The part of a van body which extends over the cab of the truck.

  • Auxiliary Transmission/AKA Brownie

    Extra transmission mounted behind the main transmission to provide additional gear splits.

  • AVI (Automatic Vehicle Identification)

    System combining an on-board transponder with roadside receivers to automate identification of vehicles. Uses include electronic toll collection and stolen vehicle detection.

  • AVL (Automated Vehicle Location)

    Class of technologies designed to locate vehicles for fleet management purposes and for stolen vehicle recovery. Infrastructure can be land-based radio towers or satellites.

  • Axle

    Structural component to which wheels, brakes and suspension are attached.

    - Drive axles are those with powered wheels.
    - Front axle is usually called the steer axle.
    - Pusher axles are unpowered and go ahead of drive axles.
    - Rear axles may be drive, tag or pusher types.
    - Tag axles are unpowered and go behind drive axles.

  • B
  • Banjo

    Rear axle drive or differential housing.

  • 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.

  • Balloon Freight

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

  • BBC

    Distance from a truck's front bumper to the back of its cab.

  • 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.

  • Binders

    Lever-type device used on trailers for securing cargo.

  • Blind Spot

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

  • Blower

    A turbo charger on diesel engines.

  • Bobtail

    Tractor operating without a trailer.

  • Bogey (also spelled bogie).

    Assembly of two or more axles, usually a pair in tandem.

  • Brake Horsepower (bhp)

    Engine horsepower rating as determined by brake dynamometer testing.

  • Bridge Formula

    A bridge protection formula used by 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 to legally be able to carry a certain weight.

  • Bulkhead

    The part of a trailer that extends vertically.

  • Bulk Freight

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

  • C
  • Cab

    The part of the vehicle that encloses the driver and operating controls.

  • Cabover (Cab-Over-Engine, COE)

    Truck or tractor design in which the cab sits over the engine on the chassis.

  • Cab Protector

    A shield covering the rear of a cab, normally constructed of steel, aluminum or mesh.

  • Camelback Suspension

    A type of heavy-duty rear spring suspension.

  • C A Dimension

    The distance from the back of the truck cab to the centerline of the rear axle. Measured in inches.

  • Cartage Company

    Company that provides local (within a town, city or municipality) pick-up 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)

    Two-way radio for which no license is required by the Federal Communications Commission (FCC). Long beyond its heyday in the '70s, CB is still used by truckers and motorists for everything from traffic condition reports to emergency calls to idle chatter.

  • CDL (Commercial Driver's License)

    License which authorizes an individual to operate commercial motor vehicles and buses over 26,000 pounds gross vehicle weight. For operators of freight-hauling trucks, the maximum size which may be driven without a CDL is Class 6 (maximum 26,000 pounds gross vehicle weight).

  • CG (Center of Gravity)

    Weight center or balance point of an object, such as a truck body. Calculated to help determine optimum placement of truck bodies on chassis.

  • Clearance Lights

    The small lights found on each corner of a trailer and on top corners of trucks and tractors.

  • Class 1-8 Truck

    Truck with the following Gross Vehicle Weight (GVW):
    CLASS           GVW
    1                        6,000 or less
    2                       6,001 - 10,000
    3                      10,001 - 14,000
    4                      14,001 - 16,000
    5                      16,001 - 19,500
    6                      19,501 - 26,000
    7                      26,001 - 33,000
    8                      33,001 and over

  • Chassis Weight (Curb Weight, Tare Weight)

    Weight of the empty truck, without occupants or load.

  • 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.

  • Common Carrier

    Freight transportation company which serves the general public. May be regular route service (over designated highways on a regular basis) or irregular route (between various points on an unscheduled basis).

  • Compensated Intracorporate Hauling

    Freight transportation service provided by one company for a sister company.

  • Container (Shipping Container)

    Standard-sized rectangular box used to transport freight by ship, rail and highway. International shipping containers are 20 or 40 feet long, conform to International Standards Organization (ISO) standards and are designed to fit in ships' holds. Containers are transported on public roads atop a container chassis towed by a tractor. Domestic containers, up to 53 feet long and of lighter construction, are designed for rail and highway use only.

  • Container Chassis

    Single-purpose semitrailer designed to carry a shipping container.

  • Contract Carrier

    Company that transports freight under contract with one or a limited number of shippers.

  • Conventional Cab

    Cab in which the engine is mounted forward of the driver compartment.

  • Converter Dolly (Dolly)

    Auxiliary axle assembly equipped with a fifth wheel (coupling device), towed by a semitrailer and supporting the front of, and towing, another semitrailer.

  • Consignee

    Interior volume of a truck body, semitrailer or trailer, measured in cubic feet.

  • Cross Member

    The portion of frame on tractors and trailers that runs at a right angle between the main and left and right frame rails.

  • D
  • Day Cab

    A tractor which has no sleeper berth. Often for local work where the driver gets home every night.

  • Dead-Heading

    Operating a truck without cargo.

  • Detention

    Extra driver pay for time spent waiting at a customer facility.

  • Disc Wheels/Budd Wheels

    A one-piece tire rim. Available in steel, chromed steel, and aluminum.

  • Diesel Exhaust Fluid (DEF)

    A chemical product that contains mostly purified water (about 68%) and urea (about 32%). In an SCR system a small injector sprays DEF as a fine mist into the exhaust stream to ultimately cause a chemical reaction in the catalyst that changes NOx to harmless nitrogen gas water vapor.

  • Diesel Particulate Filter (DPF)

    An exhaust after treatment device that removes soot from the exhaust of a diesel engine. On class 8 trucks built in the US after 2007, it replaces the muffler and traps. The DPF traps and then uses heat to oxidize the soot.

  • Displacement (Piston Displacement)

    Sum of the volumes swept by an engine's pistons as they travel up and down in their cylinders. Based upon bore (diameter of cylinder) and stroke (distance traveled by piston). Expressed in liters or cubic inches.

  • Dock Lock

    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.

  • Dolly

    An auxiliary axle assembly having a fifth wheel. Used for converting a semitrailer to a full trailer.

  • DOT

    Department of Transportation.

  • Drop Deck Trailer

    A flatbed type trailer with a belly section the same or lower than the trailer height of the axle(s).

  • Drop and Hook

    Taking a loaded trailer to a shipper/receiver, dropping the trailer (unhooking the trailer, and leaving it there at the customer's facility), and then hooking up to, and leaving with, another loaded trailer. Most drivers prefer this because there's no waiting, sometimes for hours, for your trailer to get unloaded or loaded.

  • Driveline

    All the components which together transmit power from the transmission to the drive axle(s). These consist of at least one driveshaft (propeller shaft) with a universal joint at each end.

  • Dry Freight

    Freight that's not refrigerated.

  • Doubles (Twins, Twin Trailers)

    Combination of a tractor and two semitrailers connected in tandem by a converter dolly.

  • Drive Axle

    Front and/or rear axle connected to the power unit.

  • Duplex

    A transmission having five speeds forward with a two-speed auxiliary; thus giving ten speeds forward. There are two shift levers on this transmission.

  • Dual Drive Tandem.

    Two axles having drive mechanisms connected to an engine power tandem unit.

  • DRL (Daytime Running Lights)

    System that automatically turns on a vehicle's low beam headlights when the parking brake is released and the ignition is on.

  • E
  • EDI (Electronic Data Interchange)

    The business-to-business interconnection of computers for the rapid exchange of a wide variety of documents, from bills of lading to build tickets at auto plants.

  • Exempt Carrier

    Company which transports commodities exempted from Interstate Commerce Commission (ICC) economic regulation.

  • Extended Hood

    An option or model of a Class 8 conventional truck with a longer hood. The hood normally extends an additional 12". F. E. T. Federal Excise Tax. Applied to the purchase of all new medium (33,000 lb.) and heavy-duty trucks, trailers, and equipment.

  • F
  • 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.

  • Fingerprinting

    A common term for what a driver does when he has to unload the trailer by himself.

  • Fixed Tandem

    The assembly of two axles and suspension that is attached to the chassis in one place and cannot be moved back and forth.

  • Flat Top Sleeper

    A sleeper box whose height is flush with the top of the tractor's cab.

  • Float

    An extendable flat bed or lowboy trailer.

  • Floating the Gears

    When you shift gears without using the clutch.

  • Floatation Tires

    Over-width tires with a cross-section greater than 14 inches. Applicable only to construction vehicles.

  • Fuel Tank Skirting

    Aerodynamic aid attached over the fuel tanks creating a flush face surface between the cab and frame.

  • G
  • GAWR (Gross Axle Weight Rating)

    Maximum weight an axle is rated to carry by the manufacturer. Includes both the weight of the axle and the portion of a vehicle's weight carried by the axle.

  • GCW (Gross Combination Weight)

    Total weight of a loaded combination vehicle, such as a tractor-semitrailer or truck and full trailer(s).

  • Governor

    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.

  • Geared Speed

    Calculated vehicle speed at the engine's governed rpm in each transmission gear, or (commonly) in top gear.

  • Gear Ratio

    Number, usually expressed as a decimal fraction, representing how many turns of the input shaft cause exactly one revolution of the output shaft. Applies to transmissions, power takeoffs, power dividers and rear axles. Example: If 2.5 revolutions of an input shaft cause one revolution of the output shaft, the gear ratio is 2.5:1.

  • Glider Kit

    A cab and chassis with all components except the complete drive train (engine, transmission, differential, and rear axles).

  • Grade

    Steepness of a grade, expressed as a percentage. Example: A vehicle climbing a 5% grade rises 5 feet for every 100 feet of forward travel.

  • Gradeability

    Vehicle's ability to climb a grade at a given speed. Example: A truck with a gradeability of 5% at 60 mph can maintain 60 mph on a grade with a rise of 5%.

  • GVW (Gross Vehicle Weight)

    Total weight of a vehicle and everything aboard, including its load.

  • GVWR (Gross Vehicle Weight Rating)

    Total weight a vehicle is rated to carry by the manufacturer, including its own weight and the weight of its load.

  • H
  • Hazmat

    Hazardous materials, as classified by the U.S. Environmental Protection Agency (EPA). Transport of hazardous materials is strictly regulated by the U.S. Department of Transportation.

  • Headache Rack

    Heavy protective barrier mounted behind the tractor's cab. Designed to prevent "headaches" caused by load shifting forward from the trailer and crushing the cab.

  • Heavy Duty Truck

    Truck or tractor with a gross vehicle weight in excess of 19,500 lb. (Class 6 - 8).

  • Hendrickson Suspension

    A walking beam rear suspension. Used primarily on heavy duty construction type trucks.

  • Horsepower (hp)

    Measure of power (the amount of work that can be done over a given amount of time). One horsepower is defined as 33,000 foot-pounds of work in one minute. Example: Lifting 33,000 pounds one foot in one minute, or lifting 3300 pounds ten feet in one minute.

  • Hot Shot

    A light or medium duty tractor equipped with an after-market sleeper.

  • Hours-Of-Service

    U.S. Department of Transportation safety regulations which govern the hours of service of commercial vehicle drivers engaged in interstate trucking operations.

  • I
  • In-Frame Major Overhaul

    Diesel engine overhaul performed in the vehicle. Includes the replacement of main and thrust bearings, rod bearings, cylinder liners pistons, and rings and reconditioning of the cylinder head.

  • I L S (In Lieu of Stock)

    In Lieu of Stock, i.e. a component or piece of equipment on the vehicle which differs from the standard factory equipment.

  • Interaxle Differential

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

  • IVHS (Intelligent Vehicle Highway Systems)

    Blanket term for a wide array of technologies, including electronic sensors, computer hardware and software and radio communications. The purpose of IVHS is to increase efficiency of use of existing highways, reducing travel time, fuel consumption, air pollution and accidents

  • J
  • Jackknife

    When the tractor is at an extreme angle to the trailer. Can be done intentionally, as in jackknife parking, or unintentionally, as in a jackknife accident common when slippery conditions are present.

  • Jake Brake (Engine Brake Retarder)

    A device using engine compression to slow a vehicle down, saving the vehicle's air operated brake system. Used especially on down grades.  Available only with diesel engines.

  • Johnson Bar

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

  • K
  • Kingpin

    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.

  • Kingpin Lock

    A locking device which is placed around/over the kingpin, which prevents a fifth wheel from connecting to it, and taking the trailer. Highly recommended if you plan on dropping the trailer in an unsecured location, which includes truck stops.

  • King Pin Plate

    The large flat plate surrounding the king pin on a trailer.

  • L
  • Landing Gear

    Retracting legs which support the front of a semitrailer when it is not coupled to a tractor.

  • LCV (Long Combination Vehicle)

    In general, vehicles longer than a standard doubles rig (tractor and two 28-foot semitrailers). Examples of LCVs which are permitted in some U.S. western states and eastern toll roads: Twin 48-foot trailers; triple 28-foot trailers.

  • Lift Axle

    Extra, un powered axle needed only when the vehicle is loaded, allowing it to meet federal and state vehicle weight standards. The lift axle is mounted to an air spring suspension that raises the axle when it is not required.

  • Lift Gate

    A mechanism found on the rear of a truck body that is used to load and unload heavy products. The gate is rated in pound capacity and powered either hydraulically or electrically.

  • Light Duty Truck

    Truck with a Gross Vehicle Weight of 10,000 lb. or less (Class 1 & 2).

  • 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

    Book carried by truck drivers in which they record their hours of service and duty status for each 24-hour period. Required in interstate commercial trucking by the U.S. Department of Transportation.

  • Long Nose Conventional

    A truck or tractor with a front bumper to back of cab dimensions (BBC) of 112" or more.

  • Low Boy

    Open flat-bed trailer with a deck height very low to the ground, used to haul construction equipment or 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.

  • M
  • Medium Duty Truck

    Truck or tractor with a gross vehicle weight of 10,001 to 19,500 lb. (Class 3 - 5)

  • N
  • Nose Cone

    Found on the front of van bodies and dry van trailers, this piece is attached to increase aerodynamics.

  • O
  • Operating Authority

    “Operating authority” is the term used by transportation regulatory agencies to describe a grant of legal permission by a federal or state government to engage in for-hire interstate (state-to-state) or intrastate (within a state) transportation by motor vehicle. Essentially, it is a business license

  • Out-Of-Frame Major Overhaul

    Diesel engine overhaul performed with the engine removed from the vehicle. Includes all In-Frame repairs with the addition of reconditioning the complete lower end, including the crankshaft.

  • Over The Road Tractor or Truck

    A vehicle equipped and in condition for long haul operations.

  • Owner-Operator

    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.

  • P
  • P&D

    Pickup and delivery operations

  • Pay Load

    The weight of the cargo being hauled.

  • Penthouse

    A sleeper unit and least 78" high with skylight type windows.

  • Piggyback

    A semi- trailer built with reinforcements to withstand transport by a railroad flatcar.

  • Pig Tail

    The electrical cable that connects the tractor unit with the trailer.

  • Pintle Hook

    A coupling device used in double and triple trailer, and truck-trailer combinations.

  • Placard

    A sign showing the type of hazardous materials loaded on the vehicle, placed on all four sides of a trailer.

  • Pogo Stick

    A metal pole with springs mounted behind the cab that support the air lines.

  • PTO (Power Takeoff)

    Device used to transmit engine power to auxiliary equipment. A PTO often drives a hydraulic pump, which can power a dump body, concrete mixer or refuse packer. Some designs mount to a standard opening on the transmission, while others attach at the front or rear of the engine.

  • Pusher Axle

    A non-powered truck or tractor axle set in front of powered axle.

  • R
  • Relay (Relay Driving)

    Common practice in the less-than-truckload industry, in which one driver takes a truck for 8 to 10 hours, then turns the truck over to another driver, pony express style.

  • Reefer

    Refrigerated trailer with insulated walls and a self-powered refrigeration unit. Most commonly used for transporting food.

  • Retarder

    The device used to assist brakes in order to slow a vehicle. There are many different types of retarders; including engine retarders, transmission-mounted hydraulic retarders, and axle mounted electromagnetic retarders. An engine retarder commonly called a 'Jake Brake' is used in most trucks today.

  • Runaway Truck Ramp

    Emergency area adjacent to a steep downgrade that a heavy truck can steer into after losing braking power. Usually two or three lanes wide and several hundred feet long, the ramp is a soft, gravel-filled pathway which absorbs the truck's forward momentum, bringing it to a safe stop. Depending on the surrounding terrain, the ramp may be level or run up or down hill.

  • S
  • Saddle Tanks

    Fuel tanks that are mounted along the frame just to the rear of the cab.

  • Selective Catalytic Reduction (SCR)

    An exhaust after treatment system that eliminates NOx from the exhaust of a diesel engine. The system uses a fluid (Diesel Exhaust Fluid) to crate a chemical reaction with the exhaust to convert NOx into harmless nitrogen and water vapor. On class 8 trucks built in the US after 2010, the SCR comes after the DPF, and consists of a tank for the fluid and a catalytic converter for the reaction.

  • Semi-trailer

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

  • Setback Axle

    Front steering axle moved rearward from the generally accepted standard position. Advantages: Shorter turning radius and more of a vehicle's weight shifted to front axle.

  • Short Nose Conventional

    A truck or tractor with front bumper to back of cab dimension (BBC) of 95" or less.

  • Side Fairing

    Aerodynamic aid attached to rear sides of a truck or tractor creating a flush surface from the vehicle to the trailer.

  • Six by Six (6x6)

    (Written 6X6), a tractor having six wheels driving (3 axles), i.e. a tandem rear-end with driving front axle.

  • Sleeper

    Sleeping compartment mounted behind a truck cab, sometimes attached to the cab or even designed to be an integral part of it.

  • 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).

  • Stacks

    Vertical exhaust pipes on a tractor.

  • Step Tanks

    Fuel tanks that integrate a step for access to the cab.

  • Striaght Truck

    A vehicle with the cargo body and cab mounted on the same chassis.

  • Super Singles

    Very wide tires that take the place of dual wheels on each axle. A rear tandem axle truck normally has 8 tires, however, if equipped with super singles it will have only 4. Usually found on mixers or dumps.

  • Synchronized Transmission

    Transmission with built-in mechanisms to automatically "equalize" the speed of its gears to allow smooth shifting without the need to double-clutch.

  • T
  • Tag Axle

    A non-powered truck or tractor axle set behind a powered axle.

  • Tandem Axle (Tandems)

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

  • Team Driving

    Two drivers who alternate between driving and non-driving time (sleeping, resting, etc) in order to expedite the shipment and maximize the overall production of the truck.

  • 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.

  • Tractor

    A truck designed primarily to pull a semi-trailer by the use of the fifth wheel which is mounted over its drive axle/s. May be called a truck/highway tractor to differentiate it from a farm tractor.

  • Tri-axle

    Any combination of three axles grouped together.

  • Trip Leasing

    Leasing a company's vehicle to another transportation provider for a single trip.

  • U
  • Upper Coupler

    Load bearing surface on the underside of the front of a semitrailer. It rests on the fifth wheel of a tractor or dolly and has a downward-protruding kingpin which is captured by the locking jaws of the fifth wheel.

  • Utility Bed

    A truck bed attached to the cab and chassis that has compartments and toolboxes accessible from the exterior of the bed. The interior is normally open but can be equipped with an optional enclosure.

  • V
  • VIN (Vehicle Identification Number)

    Assigned by the manufacturer, this number is unique to each vehicle and appears on the vehicle's registration and title.

  • Visibilty Window

    A window in the lower portion of the door, which enables the operator to look down on traffic.

  • VMRS (Vehicle Maintenance Reporting Standards)

    Set of codes developed to facilitate computerized tracking of parts and labor used in equipment repair. Established and maintained by the American Trucking Associations.

  • W
  • Walking Beam Suspension

    Type of truck and tractor rear suspension consisting of two beams, one at each side of the chassis, which pivot in the center and connect at the front to one axle of a tandem and at the rear to the other axle.

  • West Coast Mirrors

    Large rear view mirrors on both sides of the cab.

  • Wet Line Kit

    A hydraulic pump and reservoir assembly used to operate a dump trailer.

  • Wheel Base

    The distance between the centerlines of the front and rear axles. For trucks or trailers with tandem or tri-axles, the centerline is midway between the rear axles.

  • Wheel Power

    The total number of axles of a power unit (X) the number of wheels powered and multiplied by 2. Example is 3 axles, 2 of which are power is listed as 6x4.

  • WIM (Weigh-In-Motion)

    Technology for determining a vehicle's weight without requiring it to come to a complete stop.

  • Y
  • Yard Jockey

    Person who operates a yard tractor.

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