NH CDL General Knowledge cheat sheet

Pre-trip inspection items: brake system (air pressure, slack adjusters, drums/rotors, hoses), steering (play, linkage), lights and reflectors, tires (tread depth, inflation, damage), wheels and rims, suspension, exhaust, frame, coupling devices, and emergency equipment.

Minimum tread depth for front tires of a CMV is 4/32 inch; all other tires require at least 2/32 inch.

Steering wheel free play: 10 degrees or less on a 20-inch wheel; 10 degrees is about 2 inches of movement at the rim.

Air brake pre-trip: build pressure to governor cut-out, then check that leakage does not exceed 3 psi per minute (single vehicle) or 4 psi per minute (combination) with brakes released and engine off.

Applied leakage test: with a fully charged system and brakes applied, leakage must not exceed 4 psi per minute; hold the pedal and watch the gauge.

Low air pressure warning must activate before pressure drops below 60 psi; the spring brakes must apply between 20 and 45 psi.

Before driving, test the service brake at low speed and confirm the parking brake holds the vehicle.

Mirror adjustment: you should see the rear of your vehicle in the inner edge of each mirror and a clear view down the side; adjust before moving.

Upshift pattern for a typical 10-speed unsynchronized transmission: start in 1st, then progress through the range; use the splitter or range selector as the truck requires, and never skip gears while loaded.

Double clutching: press clutch, shift to neutral, release clutch, press clutch again, engage next gear; this matches engine and transmission speed in non-synchronized gearboxes.

Floating gears is only acceptable if you can match engine rpm precisely; if you cannot, use the clutch to avoid grinding.

Downshift before a downgrade; do not coast in neutral. Select a gear that holds your speed without riding the brakes.

Backing rule: use a helper or get out and check the area; if you must back alone, use GOAL (Get Out And Look) and back slowly with hazard lights on.

Back toward the driver's side whenever possible so the vehicle swings to the side you can see; back slowly and correct small amounts.

Right turns in a large vehicle require a wide swing to the left first, then a tight turn to keep the rear wheels from hitting the curb; watch the rear wheels in the right mirror.

Off-tracking: the rear wheels of a tractor-trailer cut the corner inside the path of the front wheels; the longer the wheelbase, the greater the off-tracking.

Following distance rule: at least one second per 10 feet of vehicle length at speeds under 40 mph, plus one extra second; at 40 mph and above, use one second per 10 feet.

At 55 mph a 60-foot combination needs at least 6 seconds of following distance; add more in rain, snow, fog, or darkness.

Aim high: look at least 12-15 seconds ahead of the vehicle, and check mirrors every 5-8 seconds.

Space cushion: keep at least one car length of space to the front and sides; avoid driving beside another vehicle, especially in its blind spot.

Use the 4-second rule for a safe gap at highway speed; if the vehicle ahead passes a fixed point before you count to 4, you are too close.

Scan for hazards: look for brake lights, turn signals, road debris, pedestrians, and vehicles entering from side streets; identify escape routes before you need them.

When stopped in traffic, leave enough space ahead to see the rear tires of the vehicle in front; this gives room to steer around if it stalls.

Blind spots: a tractor-trailer has large blind spots behind and along both sides; if you cannot see the driver's mirror, the driver cannot see you.

Total stopping distance = perception distance + reaction distance + brake lag distance + braking distance.

Perception and reaction time together are about 1.5 seconds; at 55 mph that is about 121 feet traveled before the brakes are applied.

Brake lag for air brakes is about 0.4-0.5 seconds; at 55 mph that adds roughly 32-40 feet before braking begins.

Braking distance increases with the square of speed: doubling speed roughly quadruples braking distance.

At 55 mph, a loaded tractor-trailer needs about 300 feet to stop on dry pavement; on wet or icy roads, distance increases substantially.

Speed limits: obey posted limits, and reduce speed to a safe level for curves, construction zones, and adverse weather even if the limit is higher.

On a downgrade, use a lower gear and engine braking; do not rely on the service brakes alone, which can fade from heat.

Ramp speed: enter and exit ramps at or below the posted advisory speed; rollover risk rises sharply if you enter a curve too fast.

Skids are caused by oversteering, overbraking, or driving too fast for conditions; the corrective action is to remove the cause.

Drive-wheel skid: release the accelerator and steer in the direction you want the front of the vehicle to go; do not apply brakes.

Front-wheel skid: the vehicle will not turn; release the brake or accelerator to regain steering, then steer where you want to go.

Brake-induced skid: release the brake pedal and steer to correct; with ABS, apply firm continuous pressure and steer.

Trailer jackknife: release the brakes and steer the tractor in the direction of the skid; avoid hard braking that locks the trailer wheels.

To prevent a skid, slow down before curves, brake gently, and keep the load balanced; avoid sudden steering or braking inputs.

On ice and snow, reduce speed and increase following distance; use gentle throttle and brake inputs and avoid cruise control.

If you begin to skid, look where you want to go and steer smoothly; do not stare at the obstacle.

If a tire blows, hold the steering wheel firmly, release the accelerator, and steer straight; do not brake hard until the vehicle is under control.

If the brakes fail, downshift to a lower gear, pump the brakes, use the parking brake gradually, and look for an escape route such as an uphill grade or runaway ramp.

If the accelerator sticks, shift to neutral, brake firmly, and pull off the road; turn off the engine only after stopping.

If a fire starts, stop, turn off the engine, get everyone out, and move at least 100 feet away; do not open the hood if the fire is under it.

At an accident scene: protect the area, call for help, and do not move injured persons unless there is immediate danger.

Place reflective triangles: within 10 minutes, place them at 10 feet, 100 feet, and 200 feet behind the vehicle on a two-lane road; use 100 feet and 200 feet on a divided highway.

If you are involved in an accident, stop, give aid, exchange information, and report the accident to the proper authorities.

Do not move a vehicle involved in a fatal accident until authorities arrive, unless it blocks traffic and creates a hazard.

Cargo must be secured so it cannot shift, and tiedowns must be able to withstand forward force of 0.8 g and rearward and lateral force of 0.5 g of the cargo weight.

Aggregate working load limit: the sum of the working load limits of all tiedowns must be at least half the cargo weight.

Number of tiedowns: one for cargo 5 feet or shorter and 1,100 pounds or less; two for cargo longer than 5 feet but 1,100 pounds or less; for heavier cargo, one tiedown per 10 feet of length.

Cargo must not extend more than 3 feet beyond the front of the vehicle or more than 4 feet beyond the rear; flag the rear extension if it extends 4 feet or more.

Weight limits: steer axle 12,000 pounds, tandem axle 34,000 pounds, gross vehicle weight 80,000 pounds on the Interstate System (federal limits).

Distribute weight evenly; too much weight on the rear axle can cause steering to feel light and reduce traction on the steer tires.

Check cargo and tiedowns within the first 50 miles and every 150 miles or 3 hours thereafter.

Cover loose cargo that could blow off; secure tarps and check them during the trip.

Air brake system: compressor builds pressure to about 100-125 psi; the governor cuts out around 125 psi and cuts in around 100 psi.

The low air pressure warning must come on before pressure drops below 60 psi; if it fails, do not drive.

Spring brakes apply automatically when air pressure drops below about 20-45 psi; they are held off by air pressure.

Slack adjusters: with the brakes applied, the pushrod should move no more than about 1 inch on a standard chamber; more than that indicates adjustment is needed.

ABS: an ABS light that stays on means the system is not working; the vehicle still has normal brakes but may skid on slippery surfaces.

Coolant temperature, oil pressure, and voltmeter gauges should be checked during the trip; a sudden change can indicate a problem.

Tire inspection: check for cuts, bulges, tread depth, and proper inflation; dual tires must not touch, and spacers must be in place.

Lighting: check headlights, high beams, turn signals, brake lights, clearance lights, and reflectors; ensure they are clean and working.

CDL alcohol limit: 0.04 percent BAC; a first offense results in license suspension and disqualification for at least one year.

Refusing a required alcohol or drug test results in disqualification for at least one year, the same as a positive test.

A CDL holder convicted of DUI in a personal vehicle is subject to disqualification; the rules apply on and off duty.

Controlled substances: a positive test for marijuana, cocaine, amphetamines, or other drugs results in disqualification and referral to a substance abuse professional.

Prescription and over-the-counter drugs can impair driving; check with a doctor or pharmacist and do not drive if the label warns of drowsiness.

Fatigue and illness reduce alertness; do not drive when tired, and get medical clearance after a serious illness or surgery.

Alcohol is eliminated at about one drink per hour; coffee, food, and cold showers do not speed elimination.

A driver with a BAC below 0.04 can still be cited for driving while impaired if observed behavior shows impairment.

Railroad crossing: slow down, look both ways, and listen; do not stop on the tracks.

Never drive around a lowered gate or past flashing lights; if the gate is down, stop and wait.

If your vehicle stalls on the tracks, get out and move away immediately; call the emergency number posted at the crossing.

At a crossing without gates, stop no closer than 15 feet and no farther than 50 feet from the nearest rail.

Hazardous conditions: in fog, rain, snow, or ice, reduce speed and increase following distance; use low-beam headlights in fog.

Flooded roads: do not drive through water of unknown depth; moving water can sweep a vehicle away.

High winds: reduce speed and grip the wheel firmly; be alert for sudden gusts when passing buildings or bridges.

At night, drive at a speed that lets you stop within the distance lit by your headlights.

Property-carrying drivers: 11-hour driving limit after 10 consecutive hours off duty; 14-hour on-duty window; 60 hours in 7 days or 70 hours in 8 days.

30-minute break required after 8 cumulative hours of driving without at least a 30-minute interruption.

34-hour restart: after 34 consecutive hours off duty, the 60/70-hour clock resets; the restart must include two periods from 1 a.m. to 5 a.m.

Sleeper berth split: 8/2 or 7/3 splits allow the longer period to count as off-duty time, with the shorter period counting toward the 14-hour window.

ELD: electronic logging devices record driving time automatically; paper logs are allowed only in limited circumstances such as an ELD malfunction.

Daily log must show total miles driven, start and end times, and duty status changes; keep logs current and accurate.

Fatigue signs: yawning, heavy eyes, drifting, and missing exits; stop and rest rather than pushing through.

Short naps of 15-20 minutes can improve alertness; long naps can cause grogginess, so allow time to wake up before driving.

Right-of-way: yield to vehicles already in the intersection, pedestrians in crosswalks, and emergency vehicles with lights and sirens.

School buses: stop for a school bus with flashing red lights and an extended stop arm unless you are on a divided highway with a median.

Pedestrians: yield to pedestrians in crosswalks and at intersections; do not pass a vehicle stopped at a crosswalk.

Large trucks need more room to turn and stop; do not cut in front of a truck or linger in its blind spots.

Passing: pass on the left, signal, and return to the right lane only when you can see the passed vehicle in your mirror.

Speed limits in work zones are often reduced; fines may be doubled for speeding in a construction zone with workers present.

Following emergency vehicles: do not follow closer than 500 feet; do not park within 500 feet of a fire station driveway.

Cell phone use: handheld use is prohibited for CMV drivers; texting is prohibited for all drivers in most states.