Your FREE CDL Flashcards 2026 – 100+ Cards

A commercial driver is legally intoxicated at a blood alcohol concentration of 0.04% — half the 0.08% limit for regular drivers. A first offense brings a one-year disqualification (three years if hauling hazmat).

The Model Commercial Driver License Manual published by AAMVA. States base their CDL knowledge tests on it, and the General Knowledge test comes from its 'Driving Safely' content.

The written CDL knowledge test all CDL applicants must pass (about 50 multiple-choice questions; ~80% to pass). It covers safe driving, inspection, control, and basic cargo rules.

Required for a combination of vehicles with a gross combination weight rating (GCWR) of 26,001 lb or more, where the towed unit is rated over 10,000 lb (e.g., a tractor-trailer).

Required for a single vehicle with a gross vehicle weight rating (GVWR) of 26,001 lb or more, or such a vehicle towing a unit not over 10,000 lb (e.g., a straight truck or large bus).

Required for vehicles that don't meet Class A or B but carry 16 or more passengers (including the driver) or transport placarded hazardous materials.

A vehicle that meets a CDL weight threshold (26,001+ lb), is designed to carry 16+ passengers including the driver, or transports placarded hazardous materials.

An added authority printed on a CDL that lets you operate a special vehicle or carry special cargo, earned by passing an extra knowledge (and sometimes skills) test.

A code on a CDL that LIMITS what you may operate (the opposite of an endorsement) — for example, the 'L' restriction barring air-brake vehicles.

Authorizes hauling placarded hazardous materials. Requires a written test plus a TSA security threat assessment (background check); subject to ELDT for new applicants.

Authorizes driving a tank vehicle carrying liquid or gas in a permanently mounted or portable tank of large capacity. Tested on liquid surge and tank handling.

Authorizes driving a vehicle designed to carry 16 or more passengers, including the driver. Requires a knowledge and skills test; ELDT applies to new applicants.

Authorizes driving a school bus. Requires the passenger (P) endorsement plus a school-bus knowledge and skills test; ELDT applies to new applicants.

Authorizes pulling more than one trailer (double and triple combinations). Tested by a knowledge test; requires a Class A CDL.

A combination of the Tank (N) and Hazmat (H) endorsements on one code — for drivers who haul hazardous materials in a tank vehicle.

To drive an air-brake CMV you must pass the air-brake knowledge test (and demonstrate the skills). Fail it, or test in a non-air-brake vehicle, and an 'L' restriction bars you from air-brake vehicles.

An extra knowledge test required for a Class A CDL, covering coupling/uncoupling, fifth-wheel hookup, off-tracking, and combination-specific handling.

Effective Feb 7, 2022, new applicants for a first Class A or B CDL — or the H, P, or S endorsements — must complete training from a provider on the FMCSA Training Provider Registry BEFORE the CDL test.

The FMCSA database of approved entry-level driver-training providers. ELDT must be completed with a registered provider, who reports completion electronically to FMCSA.

By holding a CDL and operating a CMV, a driver has already agreed to alcohol/drug testing when lawfully requested. Refusing a required test carries the same penalty as failing it.

Include DUI/DWI, refusing a test, leaving the scene of a crash, using a CMV to commit a felony, and driving a CMV with a revoked/suspended CDL — first offense usually means a 1-year disqualification (3 years for hazmat).

Include excessive speeding (15+ over), reckless driving, improper lane changes, tailgating, and texting/handheld phone use while driving a CMV. Two within 3 years = 60-day disqualification; three = 120 days.

A roadside order declaring a driver or vehicle unsafe to operate until the listed defects are fixed or the disqualifying condition ends. Operating in violation of an OOS order is itself a serious offense.

A document proving a commercial driver meets DOT physical-qualification standards (vision, hearing, blood pressure, etc.). The driver must carry it and keep it current to remain medically qualified.

At least 20/40 acuity in each eye (with or without correction), a 70° field of vision in each eye, and the ability to recognize standard traffic-signal colors.

The ability to perceive a 'forced whisper' at 5 feet (or meet a defined audiometric threshold) in the better ear.

21 years old to drive a CMV in interstate commerce (across state lines). Many states allow CDL holders 18+ for intrastate (within-state) driving only.

The physical commercial driver license itself, issued by your state of domicile, printed with your class plus any endorsement and restriction codes. You must carry it whenever you drive a CMV.

Safety for you and others, and to find problems before they cause a breakdown or crash. Federal and state law require inspections, and the skills test includes a vehicle-inspection portion.

Pre-trip (before driving), en-route (during the trip — watch gauges, stop to check), and post-trip (after the trip, with a written report of any defects).

1) Vehicle overview, 2) Check engine compartment, 3) Start engine/check cab, 4) Turn off engine/check lights, 5) Do the walk-around, 6) Check signal lights, 7) Start engine and check brakes.

Approach the vehicle and note its general condition, looking for damage and fresh fluid leaks (oil, coolant, fuel) on the ground under it before you begin the detailed inspection.

If a pre-trip inspection reveals a defect that affects safe operation, you must NOT drive the vehicle until it is repaired. Never drive first and report later.

A written post-trip report listing any defects found. If a previous report notes a safety defect, the driver must confirm it was repaired before driving.

At least 4/32 inch of tread on steering-axle tires and 2/32 inch on all other tires. Check for cuts, bulges, uneven wear, and correct inflation.

After starting the engine, confirm the oil pressure, air pressure, ammeter/voltmeter, coolant temperature, and warning lights all read normal as part of the cab check.

Perception distance + reaction distance + braking distance. It's how far the vehicle travels from when you see a hazard until you fully stop.

How far the vehicle travels from the moment your eyes see a hazard until your brain recognizes it (about 1.75 seconds for an alert driver — roughly 142 ft at 55 mph).

How far the vehicle travels while you move your foot from the accelerator to the brake pedal (about 0.75–1 second — roughly 61 ft at 55 mph).

How far the vehicle travels after the brakes grab until it stops. At 55 mph on dry pavement a heavy vehicle adds about 216 ft — total stopping distance is over 400 ft (longer than a football field).

Braking distance increases with the SQUARE of speed: doubling your speed (e.g., 20 to 40 mph) roughly QUADRUPLES the braking distance.

Allow at least 1 second for every 10 feet of vehicle length under 40 mph. Above 40 mph, add 1 second. A 40-ft vehicle needs 4 seconds below 40 mph, 5 seconds above.

When the vehicle ahead passes a fixed object, count 'one-thousand-one, one-thousand-two...' until your front bumper reaches the same object. The number of seconds is your gap.

The technique for shifting a manual CMV: release the accelerator, push in the clutch and shift to neutral, release the clutch, let engine rpm match road speed, push in the clutch again and shift to the next gear.

Shift up when the engine reaches the top of its recommended rpm range (use the tachometer). Shifting too early or too late wastes the engine's power band.

Devices that help slow the vehicle and save the service brakes on downgrades. Turn them OFF on wet, snowy, or icy roads because they can cause the drive wheels to skid.

A curved 'fisheye' mirror that gives a wider field of view of the sides and lower areas around the truck. Objects appear smaller and farther away than they really are.

Signal turns and lane changes early and keep the signal on until the maneuver is complete; use your horn, brake lights, and (at night) flashers to be seen and understood by others.

Space ahead is the most important — it's the area you can do the most about. Keep enough following distance to stop or steer around a hazard; large vehicles need far more room than cars.

Slow to a safe speed BEFORE entering a curve, then accelerate gently through it. Posted curve speeds are set for cars — a loaded truck or one with a high center of gravity can roll over even at the posted speed.

Traction is the grip between tires and road. On wet, snowy, or icy roads, reduce speed (by about 1/3 on wet roads, 1/2 on packed snow) because braking and steering need traction.

When a vehicle turns, the rear wheels follow a tighter path than the front wheels. Longer vehicles off-track more, so swing wide enough that the trailer tires clear the curb or corner.

Hold the wheel firmly with both hands on opposite sides. A wheel can jerk out of your hands if you hit a curb or pothole, causing loss of control.

Select a safe low gear BEFORE starting down a long grade and use the braking effect of the engine. Use the brakes in short, firm applications ('snub braking'), not steady pressure that can overheat them.

Loss of braking power from overheated brakes on long downgrades. Prevent it by going slow in a low gear and letting the engine do most of the braking instead of riding the brakes.

Keeps the wheels from locking during hard braking so you keep STEERING control. ABS may not shorten stopping distance — its benefit is control, not a shorter stop.

Brake NORMALLY — apply steady, firm pressure and let the system prevent lockup. Don't pump the brakes (pumping is for vehicles WITHOUT ABS).

If the ABS malfunction lamp stays on while driving, you still have NORMAL brakes — you've just lost the antilock function on that wheel/axle. Get the ABS repaired soon.

Any road condition or another road user that is a possible danger. Spotting hazards early gives you time to slow, steer, or change lanes before the hazard becomes an emergency.

An emergency stopping technique for vehicles WITHOUT ABS: brake fully until the wheels lock, release until the wheels roll, then reapply — keeping the vehicle straight while stopping quickly.

An EMPTY truck can actually take LONGER to stop than a loaded one — less weight on the tires means less traction, and the brakes/tires are designed for heavier loads. Drive empty trucks carefully too.

Look 12–15 seconds ahead (about a quarter mile at highway speed) so you have time to respond. Scan for road conditions, other users, and clues that a driver or pedestrian may do something unexpected.

Anything that takes your eyes, hands, or mind off driving. Texting/handheld phone use in a CMV is banned by federal rule and is a serious violation — set up navigation and devices before you start.

Aggressive driving is operating a vehicle to endanger others (tailgating, weaving). Don't engage angry drivers: stay out of their way, avoid eye contact, and don't make gestures.

Never drive faster than the range your headlights light up — low beams reach about 250 ft, high beams about 350–500 ft — or you can't stop within the distance you can see. Use high beams when legal and dim within 500 ft of oncoming traffic.

Slow down (or pull off safely and wait), use LOW beams and fog lights if equipped, and watch for slow or stopped vehicles. High beams reflect off the fog and reduce visibility.

A thin, clear layer of ice that lets dark pavement show through, so the road just looks wet. It's especially dangerous because it's nearly invisible — drivers don't slow for it.

Just below freezing with the road looking wet but no spray from other tires; ice on mirror arms, antenna, or wiper blades. These warn that black ice may be forming.

When tires ride up on a film of water and lose contact with the road, so steering and braking traction is lost. To recover, release the accelerator and let the vehicle slow — don't brake hard or steer sharply.

Standing water and speed, made worse by underinflated or worn tires. It can happen at speeds as low as 30 mph if there's enough water.

When the trailer swings around toward the tractor at a sharp angle (like a folding knife), usually caused by the trailer wheels locking up during hard braking on a slippery surface.

If the drive wheels spin and skid (often from too much power on a slippery road), STOP accelerating and push in the clutch to let the wheels turn freely and regain traction.

To recover from a front-wheel or rear-wheel skid, ease off the accelerator/brake and steer in the direction you want the vehicle to go, then countersteer to straighten out.

A truck escape ramp (runaway lane) is built on steep downgrades to stop vehicles whose brakes have failed. If your brakes fail on a grade, USE the escape ramp — don't pass it.

If brakes fail: downshift to use engine braking, pump hydraulic brakes to try to build pressure, use the parking/emergency brake gradually, and look for an escape ramp or an open escape route.

Hold the steering wheel firmly, stay off the brake at first, let the vehicle slow on its own, then brake gently once it's under control and pull off the road. Hard braking can cause loss of control.

Class A — wood/paper/cloth; Class B — flammable liquids (fuel, oil, grease); Class C — electrical fires. A B:C or A:B:C extinguisher covers the fires most likely on a truck.

Aim at the BASE of the fire, staying as far back as you can, and sweep side to side. Position yourself upwind. Never open the hood of a fire-engulfed engine — it feeds the fire oxygen.

Slow down, look both ways, and listen for a train; be ready to stop. The absence of gates or lights does NOT mean it's safe to cross without checking.

Never start across tracks unless you're sure there's enough room on the FAR side to completely clear them without stopping. A tractor-trailer needs at least 14 seconds to clear a single track. Don't shift gears while on the tracks — you could stall.

Buses with passengers and placarded hazmat vehicles must STOP 15–50 ft before the nearest rail, look and listen, then cross without shifting. Other commercial vehicles must slow and be ready to stop.

Get enough sleep before a trip, take breaks, and watch for signs of drowsiness (heavy eyes, drifting, missing exits). The only real cure for fatigue is sleep — stop and rest rather than push on.

Alcohol impairs judgment, reaction time, and vision. Only time sobers a person — coffee, fresh air, or food won't speed it up. A commercial driver is over the limit at 0.04% BAC.

Protect the area (flashers and reflective triangles behind the vehicle), notify authorities with your exact location, and care for the injured without moving them unless there's danger like fire. Don't move a seriously injured person unless necessary.

Put out reflective triangles within 10 minutes of stopping: one ~10 ft behind, one ~100 ft behind, and one ~100 ft in front (or adjusted on a divided/one-way road or near a hill/curve).

On long, steep downgrades, gravity adds speed, so go slow in a low gear and let the engine and retarder do the braking. The service brakes are backups, not the main braking method.

The maximum weight of a single vehicle plus its load specified by the manufacturer. It's the rating for one power unit including its cargo.

The maximum weight of a power unit PLUS its trailer(s) and load specified by the manufacturer. It's the combination-vehicle equivalent of GVWR.

GVW (gross vehicle weight) is the ACTUAL total weight of the vehicle and load right now; GVWR is the manufacturer's MAXIMUM rating. You must keep GVW at or below GVWR and legal axle limits.

The weight transmitted to the ground by one axle or one set of axles. Federal/state limits cap how much a single axle or tandem may carry, separate from the total gross weight.

Load cargo low and spread it evenly. A high center of gravity (heavy load stacked high) makes the vehicle tip and roll more easily in curves and quick lane changes.

Bridge limits depend on how weight is SPREAD across axles and the spacing between them, not just total gross weight — so a legal-gross truck can still be over a bridge limit.

Blocking is wedged in front of, behind, and around cargo to keep it from sliding; bracing extends from the cargo to a wall/structure to keep it from tipping or shifting.

Use at least one tiedown for every 10 feet of cargo, and always a minimum of TWO tiedowns no matter how short the load.

Cargo over 5 ft but ≤10 ft and over 1,100 lb needs at least 2 tiedowns. Cargo over 10 ft needs 2 for the first 10 ft, plus 1 more for each additional 10 ft (or fraction).

The maximum load a tiedown or securement device is rated to hold under normal use, marked by the manufacturer. The aggregate WLL of all devices must be at least half the cargo weight.

Found by adding together the working load limits of all the tiedowns and anchor points securing an article of cargo. It must equal at least 50% of the cargo's weight.

A strong barrier at the front of a flatbed or cargo area that protects the driver from cargo shifting forward during a hard stop or crash.

Placed between a strap and a sharp cargo edge so the sharp edge can't cut or weaken the tiedown. Required on metal coils and many flatbed loads.

Rubber mats placed under cargo to increase grip between the load and the deck, helping keep cargo from sliding (they can count toward securement under the rules).

Cylindrical cargo like concrete pipe or coils must be chocked, cradled, or blocked so it cannot roll sideways, forward, or backward on the deck.

Inspect cargo and securement within the first 50 miles of a trip, then re-check every 150 miles or 3 hours (whichever comes first), and whenever you change duty status.

Too much weight (or weight too high or unbalanced) makes the vehicle harder to steer and stop, harder to control on grades, and more likely to roll over or have brake/tire failure.

Sliding the fifth wheel forward shifts more of the trailer's load onto the tractor's axles; sliding it back shifts load onto the trailer axles. Adjust it to keep each axle within its legal limit.

Logs ride in bunks/stakes/bolsters that cradle them; tracked machinery is chained at strong points; transported vehicles are tied down so they can't roll, using attachments to the vehicle itself.