MN CDL General Knowledge cheat sheet

Pre-trip inspection items: engine compartment (oil, coolant, belts, hoses, leaks), lights and reflectors, tires and wheels, brakes and air lines, coupling devices, and emergency equipment.

CDL pre-trip walk-around order under 49 CFR 392.7/396.13: driver must be satisfied the vehicle is in safe operating condition before driving; report defects in writing.

Air brake leak test: with engine off, fully charged system, no brake applied, loss must be 3 psi or less per minute for a single vehicle (tractor-trailer combination: 3 psi/min for tractor, 4 psi/min for trailer).

Applied air brake leak test: with brakes fully applied, leakage must not exceed 4 psi per minute for a single vehicle and 6 psi per minute for a combination.

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

Build air pressure from 85 to 100 psi within 45 seconds at governed engine rpm (typical CDL test standard).

Tire tread minimum: 4/32 inch on steering axle tires, 2/32 inch on all other tires; no recapped or regrooved tires on the steering axle.

Two-handed steering (9 and 3 or 8 and 4 o'clock) keeps maximum control; hand-over-hand is used for sharp turns; do not palm the wheel.

Upshift pattern: accelerate to governed rpm, clutch in, shift to neutral, clutch out briefly, clutch in, select next gear, clutch out smoothly (double-clutching).

Downshift before a downgrade; do not coast in neutral and do not rely on brakes alone on long grades.

Backing rule: back only when necessary and get out to check behind the vehicle before backing; use a helper whenever possible.

When backing with a helper, keep the helper in view in the mirrors; if the helper is lost from view, stop immediately.

Right turns: swing wide but not too wide; watch the rear of the trailer off-tracking toward the inside curb.

Left turns: approach from the lane closest to the center line; do not cut the corner into oncoming traffic.

Trailer off-tracking: the rear wheels of a long combination cut inside the front wheels' path, so allow extra room on turns.

Turning radius: a longer wheelbase or trailer requires a wider swing; check mirror clearance before turning near poles or signs.

Signal at least 100 feet before turning in a business or residential area; 200 feet on highways (state rule; rural interstate may require more).

Use four-way flashers when stopped on a shoulder or moving slowly (below 40 mph on a highway) as a warning to others.

Headlights required from sunset to sunrise and whenever visibility is reduced (rain, fog, snow); many states require them when wipers are on.

Look 12-15 seconds ahead in city driving and 20-25 seconds ahead on the highway to spot hazards early.

Distraction rule: eyes off the road, hands off the wheel, or mind off driving for more than 2 seconds increases crash risk sharply.

Use mirrors systematically: check both mirrors every 5-8 seconds and before any lane change or turn.

Do not flash high beams at oncoming traffic as a signal; use horn only to warn of danger, not to express frustration.

When a vehicle passes, dim high beams and stay in your lane; do not accelerate to prevent being passed.

Following distance: at least one second per 10 feet of vehicle length at speeds under 40 mph; add one second for speeds over 40 mph. Example: 60-foot vehicle at 55 mph needs 7 seconds.

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

Perception-reaction time is about 1.75 seconds; at 55 mph that alone covers about 142 feet.

Brake lag (air brakes) adds about 0.4 seconds, roughly 32 feet at 55 mph.

Speed limit in a school zone, business district, or residential area is typically 25 mph unless posted otherwise.

Posted speed limits apply to ideal conditions; reduce speed for rain, snow, ice, fog, curves, and heavy traffic.

Space cushion: maintain at least one lane of clearance on at least one side when possible; avoid driving beside other vehicles.

Ramp speed: enter a freeway at or near highway speed; exit ramps are usually posted lower and require braking before the curve.

Hazard perception scan: look for brake lights, turn signals, merging traffic, pedestrians, and road debris 12-15 seconds ahead.

If a tire blows: hold the wheel firmly, do not brake hard, ease off the accelerator, and let the vehicle slow gradually before pulling off.

If the brakes fail: downshift, pump the brakes if air/hydraulic, use the emergency/parking brake gradually, and look for an escape route.

If the accelerator sticks: shift to neutral, brake, and pull off the road; do not turn off the engine while moving (loss of power steering/brakes).

If a front tire blows, the vehicle pulls toward that side; steer firmly against the pull and avoid hard braking.

Evasive action: brake first, then steer; do not swerve at high speed if braking is possible.

Hazardous material spill: stop, warn others, call emergency services, and stay upwind; do not attempt to clean up unless trained.

Fire: stop, shut off engine, evacuate passengers, and move at least 100 feet away before calling for help.

Skid cause: over-braking, over-steering, over-accelerating, or driving too fast for conditions.

Drive-wheel skid (rear wheels): release the brake or accelerator and steer in the direction you want the front of the vehicle to go.

Front-wheel skid: the vehicle won't respond to steering; ease off the accelerator and brake gently to regain traction.

Do not lock the brakes; threshold braking (brake to just short of lockup) preserves steering control.

On ice, reduce speed and increase following distance to at least 8-10 seconds.

Black ice forms first on bridges, overpasses, and shaded areas; treat them as slippery even if the road looks dry.

Recovery: look and steer where you want to go, not where the vehicle is sliding; avoid sudden corrections.

Anti-lock braking system (ABS): do not pump the brakes; apply firm steady pressure and steer.

Federal weight limits: 20,000 lb per single axle, 34,000 lb per tandem axle group, 80,000 lb gross vehicle weight (without permit).

Bridge formula limits weight per axle group based on the number of axles and the distance between them; check the formula before loading.

Cargo securement: at least one tiedown per 10 feet of cargo length, with a minimum of two tiedowns for any load over 5 feet.

Aggregate working load limit of tiedowns must be at least 50% of the cargo weight.

Tiedowns must be attached to the vehicle frame or rated anchor points, not to the cargo itself.

Load distribution: keep the center of gravity low and centered; heavy items over the drive axles improve traction and stability.

Front-end header board or bulkhead protects the cab from shifting cargo; rear cargo must be blocked against the tailgate.

Overhang: cargo extending more than 4 feet behind the rear must be marked with a red flag (day) or red light (night).

Air brake system components: compressor, governor, reservoirs, foot valve, slack adjusters, brake chambers, and warning buzzer/light.

Slack adjuster pushrod travel limits: typically 1 inch or less for a type 30 chamber; check the manufacturer's spec.

Coolant temperature gauge: normal operating range is typically 180-200°F; overheating can warp heads or blow gaskets.

Oil pressure warning light: stop the engine immediately and check the oil level; low pressure can destroy the engine.

Tire inspection: check for cuts, bulges, tread depth, and proper inflation; underinflation causes heat and blowouts.

Battery and charging: check for corrosion, loose cables, and alternator output; a dead battery may indicate a charging fault.

Pre-trip inspection must include the engine compartment, walk-around, and brake test; post-trip inspection is required by 49 CFR 396.11.

Dashboard warning lights (ABS, brake, oil, coolant) must be treated as stop-and-inspect signals.

Property-carrying drivers: 11-hour driving limit and 14-hour on-duty window after 10 consecutive hours off duty.

30-minute break required after 8 cumulative hours of driving (or 8 hours without a 30-minute interruption).

60/7 rule: no more than 60 on-duty hours in any 7 consecutive days; 70/8 rule: no more than 70 on-duty hours in any 8 consecutive days.

34-hour restart: after 34 consecutive hours off duty, the 60/7 or 70/8 cycle resets.

Sleeper berth split: 10-hour break may be split into two periods, one at least 7 hours and the other at least 2 hours, totaling 10.

Electronic logging device (ELD) records driving time automatically; paper logs are allowed only in limited exceptions.

Fatigue signs: yawning, heavy eyelids, drifting, missing exits, and difficulty focusing; pull over and rest.

Short-haul exception: drivers operating within a 150 air-mile radius may use timecards instead of logs under specific conditions.

Approach a crossing at a speed that lets you stop before the tracks if a train is visible or the signal activates.

Never stop on the tracks; wait until there is room on the far side before crossing.

At passive crossings (no gates or lights), stop, look both ways, and listen before proceeding; open the window to hear.

Trains cannot stop quickly: a freight train at 55 mph needs a mile or more to stop.

Do not shift gears while crossing the tracks; a stall on the tracks is a life-threatening emergency.

If the vehicle stalls on the tracks, get everyone out and move at least 100 feet away, then call 911 and the railroad emergency number.

Flashing red lights, gates, or a flagger mean stop; do not go around lowered gates.

At night, dim headlights when approaching a crossing so the engineer is not blinded.

CDL alcohol limit: 0.04% BAC (commercial drivers), lower than the 0.08% limit for non-commercial drivers.

Refusal to submit to a required alcohol or drug test results in a CDL disqualification of at least one year.

First offense of driving a CMV with BAC 0.04% or higher: one-year CDL disqualification; second offense: lifetime disqualification.

Implied consent: by holding a CDL, the driver consents to alcohol and drug testing.

Prescription and over-the-counter drugs: check with a doctor or pharmacist; never drive if the label warns of drowsiness.

Marijuana and other controlled substances are prohibited for CMV drivers, even if legal under state law.

Fatigue is a drug-like impairment: 17 hours awake impairs performance comparably to a 0.05% BAC.

Driver fitness: get 7-9 hours of sleep, avoid heavy meals before driving, and take breaks every 2 hours.

Passing: do not pass on a hill, curve, or at an intersection; return to the right lane only when the passed vehicle is visible in the mirror.

No-zone: large trucks have blind spots on both sides, directly behind, and in front; stay out of them.

Following a motorcycle or bicycle: allow at least a 3-second following distance and more in wet weather.

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

Emergency vehicles: pull to the right and stop when an emergency vehicle approaches with lights and siren.

Work zones: reduce speed, obey flaggers, and watch for workers and equipment; fines are often doubled.

Winter driving: use gentle braking and steering, and increase following distance to 8-10 seconds on ice.

Mountain driving: downshift before a downgrade and use engine braking; do not ride the brakes.