CDL study guide
CDL · Work through your exam, one topic at a time.
A Commercial Driver's License (CDL) is a credential that authorizes you to operate a Commercial Motor Vehicle (CMV) on public roads. Driving a CMV demands a higher level of knowledge, experience, skills, and physical ability than driving a non-commercial vehicle, and CDL holders are held to a higher standard whenever they operate any type of motor vehicle on public roads. The CDL study guide has 8 sections and about 2,933 words.
01General Knowledge: Safe Driving Fundamentals
The General Knowledge exam tests the driving logic behind every other endorsement: pre-trip inspection, basic control, shifting, seeing and communicating, speed and space management, night and extreme-weather driving, emergencies, and cargo securement. Learn the why behind each rule, because questions are written as short scenarios rather than definitions.
357 words, about 2 min02Air Brakes: Components, Pressures, and Tests
A compressor (engine-driven) charges the tanks; the governor cuts the compressor out near 125 psi and back in near 100 psi. A safety valve protects the tanks from overpressure, and drain valves remove water and oil.
373 words, about 2 min03Combination Vehicles: Coupling, Off-Tracking, and Brake Timing
A tractor-trailer bends at several points, so it off-tracks in turns and cut corners more sharply than a straight truck. Rearward amplification means the last trailer swings wider than the first during quick lane changes - the "crack the whip" effect.
369 words, about 2 min04Double and Triple Trailers: Converter Dollies and Stability
Doubles and triples add converter dollies , pintle hooks, and additional air and electrical connections. Each dolly carries its own set of shut-off valves and glad hands, and each coupling point must be checked individually.
380 words, about 2 min05Tank Vehicles: Liquid Surge and Rollover Risk
A partly filled tank lets liquid move. That surge pushes the vehicle forward when you brake and sideways when you turn, lengthening stopping distance and shifting weight onto tires that may already be near their limit.
383 words, about 2 min06Hazardous Materials: Placards, Papers, and Parking Rules
The hazmat endorsement requires a TSA background check and a written test. On the road, the shipping papers must be within reach of the driver (in the cab, or in a pouch on the driver's door) whenever hazmat is aboard, and they must include the hazard class, UN identification number, proper shipping name, quantity, and shipper's certification.
358 words, about 2 min07Passenger Transport: Riders, Stops, and Emergencies
Passenger drivers carry people, not freight, so the test focuses on boarding, securement of riders and their belongings, aisle and exit access, and behavior management. Riders may stand only behind the standee line ; no one stands forward of that line or on stairs while the bus is moving.
383 words, about 2 min08Vehicle Inspection and Safe Driving Skills
You will perform a pre-trip inspection , and the examiner grades how you look, not just what you say. Walk the vehicle in a fixed order and name each item: engine compartment (fluid levels, belts, hoses, steering, exhaust, leaks), then front axle (tire tread, cracks, knots, rim, hub, brakes, slack adjusters, suspension), then the coupling system, then lights and reflectors, then rear axles and cargo securement.
330 words, about 2 min