Missouri CDL General Knowledge cheat sheet

A pre-trip inspection must cover six key areas: engine compartment, cab interior and controls, lights and reflectors, walk-around exterior, coupling devices, and brakes including slack adjusters and air loss checks.

The three-part air brake test sequence: build pressure to governor cut-out, verify static leak rate (no more than 3 psi per minute for a single vehicle, 4 psi per minute for a combination), then check low-air warning activation by 60 psi.

The applied leakage test: with a fully charged system, engine off, press and hold the brake pedal; leakage must not exceed 3 psi per minute for single vehicles or 4 psi per minute for combinations.

The tractor protection valve should close and the trailer air supply should pop out between 20 and 45 psi on a combination vehicle, protecting the tractor's air if the trailer separates.

Slack adjuster push rod travel limits for a type 30 chamber are 1 3/8 inches (less than 2 inches) when the brakes are applied and the chamber is at normal operating pressure; excessive travel means brakes out of adjustment.

Tire defects that place a vehicle out of service include tread depth below 4/32 inch on any front steer tire, below 2/32 inch on other tires, and any fabric or cord showing.

Before driving, test the parking brake by setting it and gently applying engine power in a low gear to confirm it holds the vehicle; release it fully before moving.

Mirror adjustment rule: the flat side mirror should show a portion of the vehicle's side and a clear view of the lane beside it; convex mirrors show wider fields but objects appear smaller and closer than they are.

Progressive shifting: upshift at lower RPM in lower gears (for example around 1,000-1,200 RPM) and progressively higher RPM in upper gears, staying within the engine's governed range.

Double clutching sequence for a non-synchronized transmission: push clutch, shift to neutral, release clutch, press clutch, shift to the next gear; releasing in neutral lets the input shaft match gear speed.

RPM drop rule of thumb: each upshift drops engine speed by roughly 300-500 RPM depending on gear split; downshift before RPM falls below the engine's lugging threshold.

Backing rule: back only when necessary, always with a helper or spotter outside on the driver's side, and get out to check the path if no helper is available; use four-way flashers while backing.

When backing a tractor-trailer, turn the steering wheel in the opposite direction of the desired trailer movement; the trailer pivots on the drive axles, so small steering inputs correct large trailer swings.

Right turns in a large vehicle require swinging wide to the left before the turn, but never into an opposing lane; a vehicle may need to enter the far-left lane position to keep the rear wheels off the curb.

Off-tracking: the rear wheels of a long vehicle follow a path inside the front wheels' path; the longer the wheelbase, the greater the off-track, so allow extra room at corners and curbs.

Turning radius caution: a 53-foot trailer can off-track several feet inside the tractor's path; check mirrors through the turn and watch the trailer's rear wheels against curbs and poles.

The four-second following distance applies at speeds under 40 mph in ideal conditions; add one additional second for each 10 feet of vehicle length over 40 feet, and add more for rain, snow, ice, or darkness.

Stopping distance components: perception distance plus reaction distance plus braking distance. At 55 mph on dry pavement, total stopping distance for a loaded tractor-trailer is roughly the length of a football field.

Speed must be reduced by at least half on packed snow, and to a crawl on ice; the posted limit is a maximum for ideal conditions, not a target.

Downgrade rule: select a gear low enough that the engine's braking (or retarder) holds the vehicle at a steady speed without using the service brakes continuously; brake fade results from overheating.

Space cushion rule: maintain at least one car length per 10 mph of speed in front, plus a gap to the sides, and avoid driving beside other large vehicles where escape routes are limited.

Escape route scanning: identify a shoulder, empty lane, or open median before it is needed; check mirrors every 5-8 seconds and scan 12-15 seconds ahead of the vehicle.

Hazardous conditions require reducing speed by at least one-third on wet roads and more when hydroplaning risk exists; hydroplaning can begin at highway speeds with as little as 1/10 inch of water.

A hazard is any road condition or other road user that is a possible danger; hazards become emergencies when drivers fail to see or respond to them in time.

Two hazard types: those ahead that require an immediate response (a car braking suddenly) and those that require watching (a driver who may pull out); the second type must be tracked until resolved.

Clues to watch for include brake lights ahead, turn signals, drivers looking over their shoulder, children near the road, and vehicles with obscured or missing lights at dusk.

The Smith System's five keys: aim high in steering, get the big picture, keep your eyes moving, leave yourself an out, and make sure others see you.

Road surface hazards: shadows can hide potholes, ice forms first on bridges and overpasses, and wet leaves or gravel reduce traction; scan the road surface itself, not just traffic.

Intersection scanning: check left, right, and left again before entering; watch for vehicles that may run the light, and never assume a green light means the intersection is clear.

Work zones and construction areas are high-hazard zones: reduce speed, obey flaggers, watch for narrowed lanes, and anticipate sudden stops by other drivers.

Skid recovery rule: steer in the direction you want the front of the vehicle to go, and stop braking or accelerating until the tires regain traction; do not overcorrect.

Types of skids: front-wheel skid (vehicle won't turn, keep steering), rear-wheel skid (rear swings out, steer into the skid), and all-wheel skid (release brakes and steer).

Brake emergency on a downgrade: use engine braking and downshift; if brakes fail, pump the pedal, use the emergency/parking brake gradually, and look for an escape ramp or run-off area.

Tire blowout response: hold the steering wheel firmly, stay off the brakes initially, let the vehicle slow gradually, then pull off the road; sudden braking can cause a loss of control.

Crash procedures: stop, protect the scene with flashers and triangles, call 911, give first aid if trained, and do not move an injured person unless there is immediate danger.

Fire response: pull off the road, turn off the engine, get everyone out and away, and use a fire extinguisher only on small fires; never open the hood fully if the engine is on fire.

Emergency notification: report location using mile markers, exit numbers, or landmarks; stay at the scene until authorities release you, and exchange information with other drivers.

Never stop on tracks: before crossing, make sure there is room on the far side for the entire vehicle, including the trailer, before entering the crossing.

Active warning devices include flashing red lights, bells, and gates; a flashing red light means stop, and gates must never be driven around or under.

Passive warning devices include crossbucks, stop signs, yield signs, and pavement markings; a crossbuck means yield to trains, and a stop sign requires a full stop.

Trains cannot stop quickly: a freight train traveling 55 mph can take a mile or more to stop, so never try to beat a train at a crossing.

At a crossing with no gates or lights, stop, look both ways, listen with windows down, and proceed only when certain no train is approaching; multiple tracks require checking each track separately.

If a vehicle stalls on the tracks, get everyone out and away immediately, then call 911 and the railroad's emergency number posted at the crossing; do not attempt to restart the vehicle.

Never shift gears while crossing tracks; select the proper gear before the crossing and maintain steady speed to avoid stalling.

The aggregate working load limit of tiedowns must be at least 1.5 times the weight of the cargo being secured, and tiedowns must be attached to the vehicle's frame or rated anchor points.

Cargo must be secured to prevent shifting: use blocking, bracing, tiedowns, or a combination; the load must not obscure lights, reflectors, or the license plate.

Headache rack and front-end structure: cargo must be loaded so it cannot shift forward into the cab; a bulkhead or equivalent barrier is required for certain loads.

Weight limits: federal bridge formula limits axle weights; a single axle is typically limited to 20,000 lbs, tandem axles to 34,000 lbs, and gross vehicle weight to 80,000 lbs without permits.

Load height: cargo must not exceed 13 feet 6 inches in most states without a permit; check clearance signs and route restrictions for over-height loads.

Cargo inspection: check the load and tiedowns within the first 50 miles of travel, then every 150 miles or 3 hours, and after any stop or change in driving conditions.

Overhang rules: cargo extending more than 4 feet behind the vehicle requires a red or orange flag (or light at night), and front overhang limits vary by state.

Air brake system components: compressor, governor, air tanks, safety valve, and drain valves; drain air tanks daily to remove moisture that can freeze and cause brake failure.

The low-air warning must activate before pressure drops below 60 psi; the emergency spring brakes apply automatically when pressure falls to between 20 and 45 psi.

Coolant and engine temperature: check coolant level at the reservoir, never open a hot radiator cap, and watch the temperature gauge for overheating that can warp heads or seize the engine.

Tire inspection: check pressure when tires are cold, look for cuts, bulges, and tread separation, and verify lug nuts are tight; dual tires must not touch each other.

Lighting system: check headlights, brake lights, turn signals, four-way flashers, clearance lights, and reflectors before each trip; a burned-out light is an out-of-service defect.

Steering and suspension: check for excessive play in the steering wheel (more than 10 degrees free play is a defect), cracked or broken leaf springs, and loose or missing U-bolts.

Exhaust and engine systems: inspect for leaks, loose hangers, and damage; a leaking exhaust can allow carbon monoxide into the cab, and a cracked manifold is a defect.

Federal CDL alcohol limit is 0.04% BAC; a driver with a BAC of 0.04 or higher is placed out of service for 24 hours, and refusal to test is treated as a positive result.

Drivers must submit to random, reasonable-suspicion, post-accident, return-to-duty, and follow-up drug and alcohol testing under FMCSA rules.

Controlled substances: marijuana, cocaine, amphetamines, opioids, and PCP are prohibited; a positive test results in immediate removal from safety-sensitive duties.

Prescription and over-the-counter medications that cause drowsiness or impair judgment must be reported to the employer; drivers may not operate a CMV while impaired by any substance.

Alcohol testing thresholds: 0.02 to 0.039 BAC requires removal from duty for 24 hours; 0.04 or higher requires removal and referral to a substance abuse professional.

Driver fitness: report any medical condition that affects the ability to drive safely, and maintain a current medical examiner's certificate; diabetes, heart conditions, and sleep disorders may require evaluation.

Fatigue impairs reaction time and judgment similarly to alcohol; drivers must not drive when ill, exhausted, or under the influence of impairing medication.

The 11-hour driving limit: a driver may drive a maximum of 11 hours after 10 consecutive hours off duty.

The 14-hour window: a driver may not drive beyond the 14th consecutive hour after coming on duty, and the window does not pause for breaks or meals.

The 30-minute break rule: a driver must take a 30-minute break after 8 cumulative hours of driving without at least a 30-minute interruption of driving.

The 60/70-hour limit: a driver may not drive after 60 hours on duty in 7 consecutive days or 70 hours in 8 consecutive days; a 34-hour restart resets the cycle.

The 10-hour off-duty requirement: a driver must have at least 10 consecutive hours off duty before starting a new driving shift.

Sleeper berth split: drivers may split the required 10 hours into two periods, one of at least 7 hours and one of at least 2 hours, with the longer period in the sleeper berth.

Fatigue countermeasures: take breaks, get adequate sleep before trips, avoid driving during circadian low points (typically 2-6 a.m.), and recognize signs like yawning, drifting, and heavy eyelids.

Missouri follows federal FMCSA rules for CDL qualifications, hours of service, vehicle inspection, and driver testing; the Missouri CDL manual mirrors federal standards.

Missouri CDL classes: Class A for combination vehicles over 26,000 lbs with a towed unit over 10,000 lbs; Class B for single vehicles over 26,000 lbs; Class C for vehicles carrying 16 or more passengers or hazardous materials.

Endorsements: H (hazardous materials), N (tank vehicles), P (passengers), S (school bus), and T (double/triple trailers); each requires a knowledge test, and some require a skills test.

Missouri requires a DOT physical examination and a valid medical examiner's certificate for CDL holders; medical certification must be kept current.

Vehicle inspection reports: drivers must complete a pre-trip inspection and a written post-trip report noting any defects; the carrier must repair defects before the vehicle is used again.

Missouri speed limits: 70 mph on rural interstates, 65 mph on urban interstates, and lower limits in work zones and on secondary roads; CMVs may have lower limits.

Out-of-service criteria: drivers and vehicles placed out of service must remain out of service until the defect is corrected or the driver has completed the required rest period.

Pre-trip inspection must cover the engine compartment, cab, lights, walk-around, coupling devices, and brakes.

Air brake test: build to governor cut-out, check static leak (3 psi/min single, 4 psi/min combination), verify low-air warning by 60 psi.

Applied leakage test: engine off, hold brake pedal; leakage must not exceed 3 psi/min (single) or 4 psi/min (combination).

Tractor protection valve should close between 20 and 45 psi to protect tractor air if the trailer separates.

Slack adjuster push rod travel limit for a type 30 chamber is 1 3/8 inches at normal pressure; excessive travel means brakes are out of adjustment.

Out-of-service tire defects: tread below 4/32 inch on steer tires, below 2/32 inch elsewhere, or any cord showing.

Test the parking brake by setting it and applying gentle power in a low gear; release fully before moving.

Progressive shifting: upshift at lower RPM in lower gears and higher RPM in upper gears, staying within the governed range.

Double clutching: clutch in, neutral, clutch out, clutch in, next gear; releasing in neutral matches input shaft speed.

Each upshift drops engine speed roughly 300-500 RPM; downshift before the engine lugs.

Back only when necessary, with a spotter on the driver's side, four-way flashers on, and a check of the path if no spotter is available.

When backing a tractor-trailer, steer opposite the desired trailer direction; the trailer pivots on the drive axles.

Right turns require swinging wide left without entering opposing lanes; watch the rear wheels against curbs.

Off-tracking: rear wheels follow inside the front wheels' path; longer wheelbases increase off-track.

Four-second following distance under 40 mph in ideal conditions; add one second per 10 feet of vehicle length over 40 feet.

Stopping distance equals perception distance plus reaction distance plus braking distance; at 55 mph a loaded rig needs roughly a football field.

Reduce speed by at least half on packed snow and to a crawl on ice.

On downgrades, select a gear low enough for engine braking to hold speed without continuous service brakes.

Maintain at least one car length per 10 mph in front and keep an escape route to the side.

Scan 12-15 seconds ahead and check mirrors every 5-8 seconds.

Reduce speed by at least one-third on wet roads; hydroplaning can begin with 1/10 inch of water.

A hazard is any road condition or road user that is a possible danger; it becomes an emergency when not seen or handled in time.

Immediate hazards require an instant response; potential hazards must be watched until resolved.

Clues include brake lights, turn signals, drivers looking over their shoulder, children near the road, and unlit vehicles at dusk.

Smith System keys: aim high in steering, get the big picture, keep eyes moving, leave an out, make sure others see you.

Shadows can hide potholes; ice forms first on bridges; wet leaves and gravel reduce traction.

At intersections, check left, right, and left again; a green light does not guarantee a clear intersection.

Work zones require reduced speed, flagger obedience, and anticipation of sudden stops.

Skid recovery: steer in the direction you want the front to go and stop braking or accelerating until traction returns.

Front-wheel skid: keep steering; rear-wheel skid: steer into the skid; all-wheel skid: release brakes and steer.

Brake failure on a downgrade: downshift, pump the pedal, use the emergency brake gradually, and look for an escape ramp.

Tire blowout: hold the wheel firmly, stay off the brakes, slow gradually, then pull off the road.

Crash procedure: stop, protect the scene, call 911, give first aid if trained, and do not move injured persons unless in danger.

Fire: pull off, shut off the engine, evacuate, and use an extinguisher only on small fires; do not fully open a burning hood.

Report location with mile markers or exit numbers and stay until authorities release you.

Never stop on tracks; confirm room for the entire vehicle, including the trailer, on the far side before entering.

Flashing red lights, bells, and gates are active warnings; a flashing red light means stop and gates must never be driven around.

Crossbucks, stop signs, yield signs, and pavement markings are passive warnings; a crossbuck means yield to trains.

A freight train at 55 mph can take a mile or more to stop; never try to beat a train.

At crossings without gates or lights, stop, look both ways, listen with windows down, and check each track separately.

If stalled on the tracks, evacuate immediately and call 911 and the railroad emergency number posted at the crossing.

Never shift gears while crossing tracks; select the gear before the crossing and maintain steady speed.

Aggregate working load limit of tiedowns must be at least 1.5 times the cargo weight, attached to rated anchor points.

Cargo must be secured against shifting with blocking, bracing, or tiedowns, and must not obscure lights, reflectors, or the plate.

Cargo must not shift forward into the cab; a bulkhead or equivalent barrier is required for certain loads.

Federal bridge formula limits axle weights: single axle typically 20,000 lbs, tandem 34,000 lbs, gross 80,000 lbs without permits.

Cargo height must not exceed 13 feet 6 inches in most states without a permit; check clearance signs.

Inspect the load and tiedowns within the first 50 miles, then every 150 miles or 3 hours, and after any stop.

Cargo overhanging more than 4 feet behind the vehicle requires a red or orange flag, or a light at night.

Air brake components include compressor, governor, air tanks, safety valve, and drain valves; drain tanks daily to remove moisture.

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

Check coolant at the reservoir; never open a hot radiator cap; watch the temperature gauge for overheating.

Check tire pressure cold, look for cuts, bulges, and tread separation, and verify lug nuts are tight; dual tires must not touch.

Check headlights, brake lights, turn signals, four-way flashers, clearance lights, and reflectors before each trip.

Steering free play over 10 degrees is a defect; check for cracked leaf springs and loose U-bolts.

Inspect exhaust for leaks and loose hangers; a leaking exhaust can allow carbon monoxide into the cab.

Federal CDL alcohol limit is 0.04% BAC; a driver at or above 0.04 is out of service for 24 hours, and refusal to test counts as positive.

Required testing includes random, reasonable-suspicion, post-accident, return-to-duty, and follow-up tests.

Marijuana, cocaine, amphetamines, opioids, and PCP are prohibited; a positive test removes the driver from safety-sensitive duties.

Report prescription and over-the-counter medications that cause drowsiness or impair judgment; never drive impaired by any substance.

BAC of 0.02-0.039 requires 24 hours off duty; 0.04 or higher requires removal and referral to a substance abuse professional.

Maintain a current medical examiner's certificate and report conditions affecting safe driving, such as diabetes, heart conditions, or sleep disorders.

Fatigue impairs reaction time and judgment similarly to alcohol; do not drive when ill, exhausted, or on impairing medication.

The 11-hour driving limit applies after 10 consecutive hours off duty.

The 14-hour window: no driving beyond the 14th consecutive hour after coming on duty; breaks do not pause the window.

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

The 60/70-hour limit: no driving after 60 hours on duty in 7 days or 70 hours in 8 days; a 34-hour restart resets the cycle.

At least 10 consecutive hours off duty are required before a new driving shift.

Sleeper berth split: one period of at least 7 hours and one of at least 2 hours, with the longer period in the sleeper berth.

Fatigue countermeasures include breaks, adequate sleep, avoiding circadian low points (2-6 a.m.), and recognizing yawning and drifting.

Missouri follows federal FMCSA rules for CDL qualifications, hours of service, inspection, and testing; the state CDL manual mirrors federal standards.

Class A covers combinations over 26,000 lbs with a towed unit over 10,000 lbs; Class B covers single vehicles over 26,000 lbs; Class C covers 16 or more passengers or hazardous materials.

Endorsements include H (hazmat), N (tank), P (passengers), S (school bus), and T (double/triple trailers); each requires a knowledge test, and some require a skills test.

A DOT physical and a current medical examiner's certificate are required for CDL holders.

Drivers complete a pre-trip inspection and a written post-trip report noting defects; the carrier must repair defects before further use.

Missouri speed limits are 70 mph on rural interstates, 65 mph on urban interstates, and lower in work zones and on secondary roads.

Drivers and vehicles placed out of service must remain out of service until the defect is corrected or required rest is completed.