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.
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.
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.
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.
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.
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.
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.
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).
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
“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
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.
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.
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.
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.
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.
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).
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.
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.
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.