A
Axle Weight
The load carried by a single axle or axle group. Federal limits: 20,000 lbs per single axle, 34,000 lbs per tandem group. Exceeding axle weights is a violation even if gross weight is legal.
APU (Auxiliary Power Unit)
A small engine or battery system that powers the cab's heat, AC, and electronics during rest without idling the main engine. Saves fuel, reduces emissions, and complies with idling ordinances.
Alligator
CB slang for a blown tire tread lying in the road. "There's an alligator in the left lane at mile marker 204."
AMT (Automated Manual Transmission)
A transmission that shifts automatically but uses a mechanical (non-hydraulic) clutch mechanism. More fuel-efficient than traditional automatics; standard on most new semi-trucks.
B
Backhaul
A load picked up for the return trip after delivering the original load. Getting a backhaul instead of running empty (deadheading) is critical to profitability.
Bear
CB slang for law enforcement. "Bear in the air" = police helicopter. "Bear cave" = police station or weigh station. "Smokey" (from Smokey Bear) is the classic term; "county mountie" = county sheriff.
Bill of Lading (BOL)
The primary shipping document describing the freight, its origin, destination, and terms. The driver must carry the BOL for every load and present it at delivery for a signature (POD).
Black Ice
A thin, nearly invisible layer of ice on the road surface. Called "black" because it takes on the color of the road beneath it. Extremely hazardous — appears to be a wet road surface.
Bobtail
A tractor operating without a trailer attached. Counterintuitively, a bobtail truck can be harder to control than a loaded combination — the rear axles have little weight on them, reducing traction.
Broker
An intermediary who connects shippers with carriers (typically owner-operators). Brokers take a percentage of the load rate as their fee. Load boards like DAT and Truckstop.com are where many broker loads are listed.
Bunny Hop
Rapid, jerky acceleration — typically from an inexperienced driver releasing the clutch unevenly. Also used to describe small, abrupt forward movements while waiting in line at a dock.
C
Cab-Over
A truck design where the cab sits directly over the engine, with no hood protruding in front. More common in Europe; shorter overall length makes maneuvering easier in tight areas. Less common on U.S. highways today.
CDL (Commercial Driver's License)
The license required to operate commercial motor vehicles. Three classes (A, B, C) plus endorsements for special cargo (hazmat, tanker) or passenger vehicles.
Chain Law
A state regulation requiring chains or alternative traction devices on certain vehicle types when driving in winter storm conditions. Violations result in fines and potential removal from service.
Chicken Hauler
CB slang for a livestock hauler, or colloquially, any driver who runs excessively fast. Also: a truck with lots of chrome accessories.
Chocks
Wedge-shaped blocks placed against tires to prevent a trailer from rolling when parked (especially during loading/unloading). Required at many docks.
CVSA (Commercial Vehicle Safety Alliance)
The organization that coordinates roadside inspection standards in North America. Conducts International Roadcheck (annual inspection blitz) and Brake Safety Week.
Converter Dolly
A wheeled device that converts a semi-trailer into a full trailer by adding a fifth wheel, allowing it to be pulled as part of a double or triple combination.
CSA Score (Compliance, Safety, Accountability)
FMCSA's scoring system that tracks carrier and driver safety performance. High CSA scores can trigger investigations and affect a carrier's ability to get insurance or contracts.
D
DAT Load Board
One of the largest online freight marketplaces where brokers post available loads and carriers (especially owner-operators) search for freight. Competing platforms include Truckstop.com and Amazon Freight.
Deadhead
Miles driven without a paying load — either running empty to a pickup location or returning home without cargo. Deadhead miles cost the driver fuel and time with no revenue.
Detention Time
Time a driver spends waiting at a shipper or receiver beyond the free time allotted (typically 2 hours). Should be compensated by the shipper but often is not or is difficult to collect. A major driver grievance.
DVIR (Driver Vehicle Inspection Report)
The written report a driver completes after each trip noting any defects observed. Required by federal regulation — a vehicle with a safety defect may not be operated until repaired.
Doubles / Triples
Combination vehicles with two or three trailers. Requires a CDL with doubles/triples (T) endorsement. Not permitted in all states — some ban them entirely on certain road classes.
Drop and Hook
A delivery method where the driver drops a loaded trailer at a facility and hooks up a pre-loaded outbound trailer — no waiting for live loading/unloading. Preferred for efficiency.
E
ELD (Electronic Logging Device)
A federally mandated device that automatically records driving time and Hours of Service data. Connects to the truck's engine control module. Replaced paper logbooks for most drivers in 2019.
Engine Brake (Jake Brake)
A compression release braking system that uses the engine to slow the truck, reducing wear on wheel brakes. Extremely loud — banned in many residential areas. Signs reading "No Engine Brakes" are common near towns.
F
Fifth Wheel
The coupling plate on the tractor that connects to the kingpin on the trailer. The fifth wheel allows the trailer to pivot when the truck turns. Must be properly lubricated and locked for safe operation.
FMCSA (Federal Motor Carrier Safety Administration)
The federal agency within the U.S. Department of Transportation responsible for regulating commercial motor vehicles and interstate trucking. Sets HOS rules, ELD requirements, driver qualifications, and more.
Flatbed
A trailer with no sides or roof — just a flat platform. Used for oversized, heavy, or awkwardly shaped cargo (steel, lumber, machinery, construction equipment). Requires careful load securement with chains, straps, and binders.
Four Wheeler
CB slang for any passenger car or light vehicle (as opposed to an 18-wheeler). Often used when warning about car traffic patterns around the truck.
G
Gladhands
The air line couplings that connect the tractor's air brake system to the trailer. Two lines: service (blue) and emergency/supply (red). Must be properly connected before moving a trailer.
Gross Vehicle Weight (GVW / GVWR)
The total weight of the vehicle including the tractor, trailer, and all cargo. Federal limit on most highways: 80,000 lbs. GVW Rating is the manufacturer's maximum safe operating weight.
H
Hazmat
Hazardous materials — substances regulated by the DOT for transport due to flammability, toxicity, reactivity, or other dangerous properties. Nine classes, from explosives to radioactive material. Requires CDL H endorsement and additional training.
HOS (Hours of Service)
Federal regulations governing how many hours a commercial driver may drive and work before mandatory rest. See Regulations Guide for full details.
Hot Shot
A carrier using a pickup truck (often with a gooseneck trailer) for expedited freight delivery. Typically used for smaller, time-sensitive loads. Not subject to all the same regulations as Class 8 trucking but growing in the industry.
I
IFTA (International Fuel Tax Agreement)
An agreement among U.S. states and Canadian provinces that simplifies fuel tax reporting for interstate carriers. Drivers report miles traveled and fuel purchased in each jurisdiction quarterly, and taxes are redistributed accordingly.
IRP (International Registration Plan)
A reciprocity agreement for commercial vehicle registration across states and provinces. Trucks operating in multiple jurisdictions register under IRP and pay proportional registration fees based on miles driven in each state.
J
Jake Brake
Common name for a compression release engine brake (named after the Jacobs Vehicle Systems brand). See "Engine Brake."
Jockey
A yard truck or yard dog — a small, specialized truck used to move trailers around a shipping yard or warehouse dock area. Also the act of maneuvering a trailer into position.
K
Kingpin
The steel pin on the front underside of a semi-trailer that locks into the fifth wheel of the tractor. The coupling point for the entire combination vehicle.
K-Whopper
CB slang for a Kenworth truck (K-W).
L
LTL (Less Than Truckload)
A shipping method where a single trailer carries freight from multiple shippers going to multiple destinations. The carrier consolidates loads. Contrasted with FTL (Full Truckload) where one shipper fills the whole trailer.
Landstar
One of the largest asset-light trucking companies in the U.S., known for using independent agents and owner-operators. Often used as a benchmark in discussions about owner-op pay structures.
Log Book
The record of a driver's on-duty, off-duty, sleeper berth, and driving time. Now typically maintained on an ELD rather than paper. Must be accurate and available for inspection.
M
Medical Card
The DOT medical examiner's certificate showing the driver has passed a physical and is medically qualified to operate a CMV. Must be carried at all times while driving and presented during roadside inspections.
Mileage Pay
The most common pay structure for company OTR drivers — paid per mile driven. Typically ranges from $0.50 to $0.75+ per mile depending on carrier and experience. Does not compensate for non-driving time.
N
Net Per Mile
An owner-operator's profitability metric: load revenue minus all expenses (fuel, tolls, maintenance, insurance) divided by miles driven. Industry rule of thumb: $1.50–$2.00+ net per mile is healthy for owner-ops.
NBI (National Bridge Inventory)
The federal database of all bridges in the U.S., including clearances, weight limits, and structural ratings. CleanShot uses NBI data to warn drivers of low-clearance structures ahead.
O
OTR (Over the Road)
Long-haul trucking where drivers are away from home for extended periods (days to weeks). Contrasted with regional (home most weekends) or local (home daily) routes.
Out-of-Service (OOS)
A vehicle or driver placed out-of-service by an inspector cannot move until the violation is corrected. OOS violations for vehicles typically involve critical safety defects; for drivers, hours of service violations are most common.
Owner-Operator
An independent truck driver who owns (or leases) their own equipment and operates as an independent business, contracting freight directly or through carriers. Responsible for all expenses including insurance, fuel, maintenance, and taxes.
P
Permit Load / Oversize Load
Cargo exceeding standard legal dimensions or weight limits that requires a state permit to move. Often restricted to daylight hours, certain days, and specific routes. May require pilot cars or law enforcement escort.
POD (Proof of Delivery)
The signed Bill of Lading or delivery receipt confirming freight was received at destination. Required for the carrier to invoice the shipper and for the owner-op to get paid.
PrePass
An electronic clearance system that allows trucks to bypass weigh stations if their weight and credentials check out electronically. A green light means keep rolling; red means pull in. Saves significant time on long runs.
Reefer
A refrigerated trailer used to transport temperature-sensitive cargo (food, medicine, chemicals). The refrigeration unit (also called a "reefer unit") runs on diesel. Reefer loads typically pay a premium due to equipment costs and monitoring requirements.
R
Rate Per Mile
The amount a shipper or broker pays per mile for a load. Current market rates fluctuate with fuel prices, seasonality, and supply/demand. Gross rate per mile minus operating costs equals net per mile profit.
Reefer
A refrigerated trailer. See above under P (listed for searchability).
Runaway Truck Ramp
An emergency escape ramp built into steep downhill grades, filled with deep gravel or sand to stop a truck whose brakes have failed. Using a ramp is preferable to any alternative — trucks that use them are not ticketed.
S
Scale Ticket
The receipt issued after a truck is weighed at a weigh station, showing gross weight and individual axle weights. Drivers should keep scale tickets as documentation — they're useful for IFTA records and load history.
Shipper
The company or individual sending freight. The shipper arranges the load, prepares the BOL, and is responsible for proper loading (in many cases). The shipper pays the carrier or broker for transportation.
Sleeper Berth
The sleeping area in a truck cab, located behind the driver's seat. Varies from basic bunks to full "condo" configurations with TVs, refrigerators, and standing room. A driver's home for weeks at a time on OTR routes.
Spread Axle
A trailer configuration where the rear axles are spread farther apart (up to 10 feet instead of the standard ~52 inches). Allows higher legal weight on rear axles and better weight distribution. Common on flatbeds carrying heavy machinery.
T
Tanker
A trailer designed to carry liquid or bulk dry cargo. Liquid tankers have unique handling characteristics — liquid shifts when the truck turns or brakes (surge effect), requiring special training. CDL N endorsement required.
Tarping
Covering an open flatbed load with heavy canvas or vinyl tarps to protect cargo from rain, road debris, and damage. Tarping is physically demanding work — tarps weigh 50–100 lbs each and must be properly secured at highway speed.
Team Driving
Two drivers sharing one truck, alternating between driving and sleeping in the berth. Allows nearly continuous operation — one driver drives while the other rests. Common for time-sensitive expedited freight.
Tractor
The powered portion of a semi-truck combination — the cab and engine. Also called the "power unit." The tractor is separate from (and can operate without) its trailer.
U
USDOT Number
A unique identifier assigned by the FMCSA to commercial vehicles. Required to be displayed on both sides of any CMV used in interstate commerce. Used to track safety records, compliance history, and inspections.
Unloaded Vehicle Weight (UVW)
The weight of the vehicle without cargo or passengers. Also called tare weight. Used to calculate available payload capacity within legal weight limits.
V
Van
Short for dry van — an enclosed box trailer used for general freight. The most common trailer type. No temperature control. Typical interior dimensions: 53 feet long, 8.5 feet wide, 9 feet tall.
Violations (CSA)
Safety violations recorded during roadside inspections that feed into a carrier's or driver's CSA score. Categories include HOS, vehicle maintenance, driver fitness, controlled substances, and hazmat.
W
Weigh Station
A roadside facility where trucks are weighed to enforce legal weight limits. May also conduct safety inspections. Some use weigh-in-motion technology to screen trucks at highway speed — only overweight or flagged trucks must pull in fully.
Weight Restriction
A reduced weight limit applied to specific roads or bridges — often seasonally (spring thaw) or permanently due to structural limitations. Violating a posted weight restriction carries significant fines.
Wiggle Wagon
CB slang for a double or triple trailer combination.
Y
Yard Dog / Yard Jockey
A small truck used exclusively for moving trailers around a yard or distribution center. Not licensed for public road use. The drivers who operate them are called yard jockeys.
Z
ZIP Fuel
Industry term for diesel fuel with additives to improve cold-weather performance (winterized diesel). Prevents gelling in extreme cold. Important for drivers running northern routes in winter.
When we set out to build CleanShot, one of the first things we did was learn the language. Not just the DOT acronyms and the regulatory terms — the real language. "Alligator in the hammer lane." "Bear taking pictures." "Chicken hauler pushing 80 through a scale." The way drivers actually talk about their world.
Because here's what we believe: you can't build useful software for an industry you don't understand. You can't build it from a conference room looking at market research slides. You have to actually know what detention time costs a driver, why PrePass matters, what it means when a reefer unit goes down in Arizona in July. We know these things. That knowledge is baked into every decision we make about CleanShot.
The trucking industry is the backbone of this country's economy. Most people never think about it — they just expect the shelves to be stocked and the packages to arrive. At CleanShotHQ, we think about it every day. This glossary is part of how we make sure that everyone on our team thinks about it too — with the same respect for the craft that the drivers who live it deserve.