NC CDL General Knowledge cheat sheet

Pre-trip inspection is required by federal rule (49 CFR 396.13) before driving; the driver must be satisfied the vehicle is in safe operating condition.

After-trip inspection is required at the end of each day's work and must cover the same items as the pre-trip; defects go on the written report.

Seven-step walk-around: (1) left front and engine compartment, (2) front axle and steering, (3) right front and side, (4) right rear and duals, (5) rear and lights, (6) left rear, (7) left side and coupling area.

Brake test order before moving: parking brake applied, service brake applied, then release parking brake and check for movement (leak-down and pull tests).

Air brake inspection thresholds: with engine off and full pressure, loss must be under 2 psi in 1 minute (single vehicle) or 3 psi in 1 minute (combination); low-air warning must activate by 60 psi.

Tire rules: minimum tread depth 4/32 inch on steering axle and 2/32 inch on all other axles; no cuts exposing cords, no sidewall bulges.

Lighting check: headlights (high and low), clearance and marker lights, turn signals, four-way flashers, brake lights, and reflectors must all work.

CDL pre-trip test requires naming each item and stating what a defect looks like; skipping a required item is an automatic failure.

Steering: keep both hands on the wheel; hand-over-hand is permitted on a CDL test, but never palm the wheel or let it spin free.

Manual transmission: start in the correct gear, do not coast in neutral, and never shift while crossing railroad tracks.

Automatic transmission: come to a full stop before shifting between drive and reverse; never shift to reverse while moving forward.

Backing: back only when necessary, use a helper or get out and look, back toward the driver's side (left) when possible, and back slowly.

Speed and stopping distance: total stopping distance = perception distance + reaction distance + brake lag distance + braking distance.

Brake lag for air brakes is about 0.4 second (roughly 32 feet at 55 mph) before braking force begins.

Turning: a large vehicle may need to swing wide; turn slowly and check mirrors throughout the turn to keep the rear wheels clear of the curb.

Retarder/engine brake use: never use on slippery surfaces; use only on dry pavement with the drive wheels gripping.

Manual transmissions: shift up in the correct sequence and do not skip gears unless the transmission and load permit it; double-clutching is required in non-synchronized transmissions.

Downshift before a downgrade and before entering a curve; do not coast downhill in neutral or with the clutch depressed.

Match engine rpm to road speed; upshift before the engine reaches governed rpm, downshift before it lugs.

Use the clutch fully: press to the floor to shift, release smoothly; do not ride or slip the clutch.

On upgrades, downshift before the engine loses power; waiting until the engine lugs can stall the vehicle.

Automatic transmissions: select a lower range before a long downgrade to use engine braking, and never shift to neutral to save fuel.

Progressive shifting (skip-shifting) is a fuel-saving technique taught by some carriers but requires manufacturer/company approval.

If a shift is missed, do not force it; return to neutral, match rpm, and re-select the gear.

Following distance rule: at least one second per 10 feet of vehicle length at speeds under 40 mph; add one second above 40 mph. A 60-foot vehicle needs 6 seconds under 40 mph and 7 seconds above.

Use the 4-second rule as the minimum for cars and light trucks; add one second for each adverse condition (rain, darkness, heavy traffic).

Scan 12-15 seconds ahead (about one city block in town, a quarter mile on the highway).

Check mirrors every 5-8 seconds and before any lane change, turn, or stop.

Communicate with turn signals, four-way flashers, brake lights, headlight flashing, and horn; signal at least 100 feet before a turn (some states require more).

Use the horn only to warn others; a loud horn is required equipment on commercial vehicles.

Blind spots: large trucks have no-zone areas on both sides, directly behind, and in front; if you cannot see the driver's mirror, the driver cannot see you.

At night or in low light, use low beams when following or meeting traffic; high beams when alone on an open road.

Speed must be reasonable and prudent for conditions, not merely the posted limit; the basic speed law applies in every state.

Total stopping distance grows with the square of speed: doubling speed roughly quadruples braking distance.

Perception and reaction time average about 1.75 seconds combined; at 55 mph that is roughly 142 feet before the brakes apply.

On wet pavement, braking distance roughly doubles; on ice it can be 10 times the dry distance.

Enter curves at a safe speed before the curve; brake before the curve, not in it.

On downgrades, select a low gear before the grade and use engine braking; do not ride the brakes, which can fade or fail.

Work zone and school zone limits are strictly enforced; fines are commonly doubled when workers are present.

Adverse weather: reduce speed by at least one-third on wet roads and by half or more on snow or ice.

Space cushion: keep at least one lane width on each side when possible; avoid driving beside another vehicle.

Ahead: maintain the one-second-per-10-feet rule plus one second above 40 mph; behind: allow room for a tailgater to stop if you must brake.

When stopped behind another vehicle, leave enough space to see its rear tires touching the road, so you can steer around it.

Lane changes: check mirrors, signal, check blind spot, and change one lane at a time.

Passing: complete the pass only when you can see the passed vehicle's headlights in your mirror and there is clear space ahead.

Railroad crossings: never stop on the tracks; if the gate comes down, drive through it rather than stop on the crossing.

Merge and exit: adjust speed to traffic flow; do not force a merge or cross solid lines.

Hills and curves: reduce speed before cresting a hill or entering a curve so you can stop within the visible distance.

Rain: hydroplaning begins at highway speed with as little as 1/10 inch of water; reduce speed and avoid standing water.

Fog: use low beams, slow down, and increase following distance; never use high beams in fog.

Snow and ice: gentle steering, gentle braking, and low gear; avoid cruise control and sudden throttle.

Hot weather: watch tire pressure and tread; heat raises pressure and increases blowout risk.

Cold weather: check antifreeze, battery, and air dryer; drain air tanks daily to remove moisture that can freeze.

Construction zones: expect narrowed lanes, uneven pavement, and workers; obey flaggers and reduce speed.

Strong wind: grip the wheel firmly, reduce speed, and watch for sudden gusts at bridges and open areas.

Flooded roads: never drive through moving water; 6 inches of moving water can knock a person down, 12 inches can move a car.

Brake failure: pump the brakes, downshift, use the parking brake gradually, and look for an escape route.

Tire blowout: hold the wheel firmly, do not brake hard, let the vehicle slow, then pull off the road.

Skid: steer in the direction you want the front of the vehicle to go; do not brake hard until the wheels regain traction.

Hydroplane: ease off the accelerator, do not brake or steer abruptly, and wait for the tires to regain contact.

Fire: stop, shut off the engine, get everyone out and away, and call emergency services before attempting to fight a small fire.

Stuck accelerator: shift to neutral, brake firmly, and pull off the road when safe.

Runaway on a downgrade: use engine braking, escape ramps, or a safe turnout; never ride the brakes.

Emergency stop on the shoulder: turn on four-way flashers, set out reflective triangles (within 10 minutes, 10 feet/100 feet/200 feet placement rules).

Before a downgrade, check brakes, select a low gear, and check the load is secure.

Use the same gear going down that you used going up; do not upshift on the grade.

Engine braking and retarders control speed; brakes are for slowing, not for holding speed on a long grade.

Watch for brake fade: if brakes feel weak or the pedal goes to the floor, pull over and let them cool.

Escape ramps are for runaway vehicles; do not stop or park on them.

Upgrades: downshift before the engine lugs; watch the temperature gauge and stop if it overheats.

Mountain curves: reduce speed before the curve and stay in your lane; do not cross the center line.

Altitude affects engine power and can affect air compressor output; watch gauges closely.

Headlights must be on from sunset to sunrise and whenever visibility is limited; many states require them in rain or fog.

Use low beams within 500 feet of oncoming traffic and within 200 feet when following another vehicle.

Do not look directly into oncoming headlights; look toward the right edge of your lane.

At night, reduce speed so you can stop within the distance illuminated by your headlights.

Increase following distance at night; the one-second-per-10-feet rule still applies, and add time for reduced visibility.

Watch for pedestrians, cyclists, and animals; they are harder to see at night and may not be visible until close.

Dirty or misaimed headlights reduce visibility; clean them and check aim regularly.

Fatigue is a major night hazard; stop and rest if you feel drowsy, and do not rely on caffeine or the radio.

Cargo must be secured to prevent shifting; use tiedowns with a working load limit of at least 50% of the cargo weight.

Aggregate working load limit of tiedowns must be at least 1.5 times the cargo weight for most loads.

Cargo must not extend more than 3 feet beyond the front or 4 feet beyond the rear of the vehicle without a flag or light.

Hazardous materials: placards are required for most quantities; placards must be on all four sides of the vehicle.

Shipping papers must be within reach of the driver and include the proper shipping name, hazard class, and UN number.

Never smoke or use open flame near hazardous materials; keep fire extinguishers accessible.

Loads must not exceed axle or gross weight ratings; check scales and axle weights.

Secure tarps and covers so they do not flap or tear; inspect tiedowns and straps for wear before each trip.

Passenger vehicles: stop only at designated stops, load and unload safely, and never move until passengers are seated or holding handholds.

Standees are not permitted on buses unless the bus is designed for them; never allow passengers to ride on the outside of the vehicle.

Check the bus after each trip for sleeping passengers, lost items, and hazards; do a complete interior check.

Emergency exits must be clearly marked and unobstructed; know how to operate each type.

Air brake system: compressor builds pressure, governor cuts out around 120-125 psi and cuts in around 85-100 psi.

Low-air warning must activate by 60 psi; spring brakes apply automatically when pressure drops to about 20-45 psi.

Air brake test: with engine off, apply brakes and hold; loss must be under 2 psi (single) or 3 psi (combination) per minute.

Air dryer and tanks: drain moisture daily; moisture in the system can freeze and cause brake failure.