General Knowledge Practice Questions

Explanation: Total stopping distance = perception distance + reaction distance + braking distance. Vehicles with air brakes also add brake lag.

Explanation: On a wet road, tires can lose contact and hydroplane at speeds as low as 30 mph, especially with low tire pressure or worn tread.

Explanation: On a two-lane or undivided road: one within 10 feet of the rear corner on the traffic side, one about 100 feet behind, and one about 100 feet ahead. On a one-way or divided highway: 10, 100 and 200 feet behind.

Explanation: The CDL manual's inspection standard is at least 4/32 inch of tread in every major groove on front tires and 2/32 inch on other tires.

Explanation: Steering wheel play of more than 10 degrees — about 2 inches of movement at the rim of a 20-inch steering wheel — can make it hard to steer.

Explanation: Federal rules disqualify a CDL holder driving a commercial motor vehicle with a BAC of 0.04% or more — half the usual limit for car drivers.

Explanation: Check cargo and tie-downs within the first 50 miles, then every 3 hours or 150 miles, whichever comes first, and after every break.

Explanation: The CDL manual calls for at least one tie-down for every 10 feet of cargo, and always at least two tie-downs, however small the cargo.

Explanation: Shift down before you start the grade. Trying to downshift once speed builds can leave you unable to get into a lower gear.

Explanation: Once in the right low gear, apply the brakes hard enough to slow to about 5 mph below your safe speed, then release. When you are back at the safe speed, repeat. Long, light braking overheats the brakes.

Explanation: Escape ramps are built to stop runaway vehicles safely. If your brakes fail on a grade, use one.

Explanation: Turn slowly, keep the rear close to the curb to stop other vehicles passing on your right, and if you must swing wide, do it as you complete the turn.

Explanation: Use low beams within 500 feet of an oncoming vehicle, and when following another vehicle closely.

Explanation: Convex mirrors show a wider area but make things look smaller and farther away than they really are.

Explanation: CMVs carry an extinguisher rated B:C, for flammable liquids and electrical fires. Never use water on a fuel or electrical fire.

Explanation: For a drive-wheel acceleration skid, stop accelerating so the wheels can roll again, and push in the clutch if you have one so the engine does not keep driving them.

Explanation: Caffeine, fresh air and music only mask fatigue for a short time. The only cure is sleep.

Explanation: An empty vehicle has less weight on the tires and so less traction. Stiff suspension and strong brakes can lock the wheels, so stopping can take longer.

Explanation: Pump the brake pedal three times, then press firmly and hold for five seconds. If the pedal moves, there may be a leak or other problem; get it fixed before driving.

Explanation: Slow to a safe speed before entering the curve. Braking in a curve can lock the wheels and cause a skid. The posted speed may be too fast for a truck.

Explanation: Weight compresses the suspension, so a loaded vehicle sits lower. If you passed under a bridge when loaded, you may not clear it empty.

Explanation: When a stop is required, stop within 50 feet but not closer than 15 feet to the nearest rail, then listen and look in both directions.

Explanation: Pick a gear that lets you cross without shifting. Missing a shift on the tracks could stall the vehicle there.

Explanation: The CDL manual says a typical tractor-trailer takes about 14 seconds to clear a single track, and more than 15 seconds for a double track.

Explanation: Top-heavy vehicles can usually steer around a hazard faster than they can stop. Don't brake while turning sharply, or you may skid.

Explanation: Keep one set of wheels on the pavement if you can, avoid braking until speed drops to about 20 mph, then brake gently. Return to the road when it is safe.

Explanation: Hold the wheel firmly, stay off the brakes until the vehicle has slowed, then brake gently, pull off the road and stop.

Explanation: FMCSA rules prohibit CMV drivers from texting and from using a hand-held mobile phone while driving, including while stopped temporarily in traffic. Violations can lead to fines and disqualification.

Explanation: GVWR is the manufacturer's maximum loaded weight for a single vehicle. GCWR is the maximum for a combination.

Explanation: Never remove the radiator cap on a hot engine. Hot coolant under pressure can spray out and cause severe burns.

Explanation: Bridges freeze before the rest of the road because cold air passes above and below them. Be careful when the temperature is near freezing.

Explanation: Black ice is a thin layer that is clear enough to see the road underneath, so the road just looks wet. Watch for ice building on mirrors, antennas and wipers.

Explanation: The best advice is not to drive in fog. If you must, slow down and use low beams; high beams reflect off the fog and make it harder to see.

Explanation: Back toward the driver's side so you can see better, back slowly, and use a helper when you can. Agree on hand signals first.

Explanation: Turn on the four-way emergency flashers when you stop, and place your warning triangles within 10 minutes.

Explanation: Under implied consent, CDL holders are considered to have agreed to alcohol testing. Refusing leads to disqualification.

Explanation: Drivers of vehicles carrying hazardous materials that require placards must have the H endorsement, which includes a knowledge test and a TSA security threat assessment.

Explanation: Climbing in too high a gear lugs the engine and builds heat. Downshift to keep engine speed in the recommended range and watch the temperature gauge.

Explanation: You need a CDL for a single vehicle with a GVWR of 26,001 pounds or more, or a combination with a GCWR of 26,001 pounds or more.

Explanation: A first offense such as driving a CMV at .04% BAC or higher, refusing an alcohol test, or leaving the scene of a CMV crash costs your CDL for at least 1 year.

Explanation: The usual 1-year disqualification rises to at least 3 years when the offense happens in a CMV placarded for hazardous materials.

Explanation: A second major offense brings a lifetime CDL disqualification.

Explanation: Serious traffic violations include excessive speeding of 15 mph or more over the limit, reckless driving, improper lane changes and following too closely.

Explanation: Two serious violations within 3 years mean at least 60 days; three or more within 3 years mean at least 120 days.

Explanation: The first out-of-service order violation costs at least 90 days; two in 10 years cost at least 1 year; three or more in 10 years cost at least 3 years.

Explanation: The T endorsement covers double/triple trailers. N is tank, P is passenger, and X is the combined tank and hazardous materials endorsement.

Explanation: You may never drink on duty, or drink any intoxicating beverage, regardless of alcohol content, within 4 hours before going on duty.

Explanation: If 1/4 or more of the leaves in any leaf spring are missing, the vehicle is put out of service, though any spring defect can be dangerous.

Explanation: A broken exhaust system can let poison fumes into the cab or sleeper berth. Look for loose, broken, missing or leaking exhaust parts.

Explanation: Required warning devices are 3 red reflective triangles, 6 fuses, or 3 liquid-burning flares, along with a fire extinguisher and spare fuses.

Explanation: Rust around wheel nuts may mean the nuts are loose, so check their tightness.

Explanation: The ABS light should come on and then go off. If it stays on, the ABS is not working properly.

Explanation: With the parking brake set and the vehicle in a low gear, gently pull forward to make sure the brake holds. If it does not hold, get it fixed.

Explanation: Sign the report only if the defects noted were certified as repaired or not needed. You, not the mechanic, are responsible for the vehicle's safe operation.

Explanation: Partly engage the clutch before you take your right foot off the brake, and use the parking brake if needed to keep from rolling back.

Explanation: On poor traction the retarder may cause the drive wheels to skid, so turn it off whenever the road is wet, icy or snow covered.

Explanation: Selecting a low range keeps the transmission from shifting up beyond the selected gear and gives greater engine braking on downgrades.

Explanation: Check mirror adjustment before each trip with the trailer straight, and set each mirror to show part of the vehicle as a reference point.

Explanation: Signal early, signal continuously until the turn is finished, and cancel the signal afterward. Signaling early keeps others from trying to pass you.

Explanation: Do not signal other drivers that it is safe to pass. It could cause an accident and you could be blamed.

Explanation: Place warning devices back beyond any hill, curve or obstruction that blocks the view within 500 feet, moving the rearmost triangle back.

Explanation: Average perception time for an alert driver is 1 3/4 seconds. Average reaction time is 3/4 second to 1 second.

Explanation: Doubling speed from 20 to 40 mph makes the impact and the braking distance 4 times greater. Tripling to 60 mph makes them 9 times greater.

Explanation: Wet roads can double stopping distance. Reduce speed by about 1/3 on wet roads, by half or more on packed snow, and to a crawl on ice.

Explanation: Right after rain begins, the water mixes with oil left on the road, making it very slippery until continued rain washes the oil away.

Explanation: Always be able to stop within the distance you can see. Fog, rain and night driving with low beams may require you to slow down.

Explanation: Use engine braking as the main way to control speed on downgrades. It is strongest near governed rpm in the lower gears.

Explanation: Another driver may suddenly turn into you, and you may have no room when you need to change lanes. Find an open spot away from other traffic.

Explanation: Repaving or packed snow can reduce clearance after the height was posted. If you doubt you can clear, go slowly or take another route.

Explanation: Some roads make a vehicle tilt toward roadside objects. Where this is a problem, drive a little closer to the center of the road.

Explanation: Always take the right lane of two turning lanes. Starting in the inside lane may force you to swing right during the turn.

Explanation: Space under a heavily loaded vehicle can be very small. Drainage channels can make the ends of some vehicles drag, so cross carefully.

Explanation: Slow vehicles such as farm and construction machinery may display the slow moving vehicle emblem, a red triangle with an orange center.

Explanation: Confused drivers often change direction or stop without warning. Clues to tourists include car-top luggage and out-of-state plates.

Explanation: Texting requires looking at a small screen and using your hands, so it combines physical and mental distraction.

Explanation: Give a distracted driver plenty of room and maintain a safe following distance. Be very careful passing, because they may drift in front of you.

Explanation: With low beams you can see about 250 feet ahead, and with high beams about 350 to 500 feet, so drive slowly enough to stop within that range.

Explanation: Dirty headlights may give only half the light they should, which cuts your vision and makes it harder for others to see you.

Explanation: A bright cab makes it harder to see outside. Keep the interior light off and dim the instrument lights as low as you can while still reading them.

Explanation: Trying to push on when tired is a major cause of fatal accidents. Stop and go to sleep for the night or take a 15 to 20 minute nap.

Explanation: A lack of spray from other vehicles indicates ice has formed. Ice on your mirrors or wiper blades is another clue.

Explanation: Remove ice from the radiator shutters and do not close the winterfront too tightly, or the engine may overheat and stop.

Explanation: Slow down, use a low gear, and keep light pressure on the brakes to keep water and mud out. Afterward, keep light pressure briefly to dry them and make a test stop.

Explanation: In very hot weather, check tire mounting and air pressure every 2 hours or 100 miles.

Explanation: At a passive crossing there are no lights or gates; the decision to stop or proceed is entirely yours. Active crossings have lights, bells and/or gates.

Explanation: The round, black-on-yellow advance warning sign tells you to slow down, look and listen, and be ready to stop for a train.

Explanation: Stop when the lights begin to flash and before the gate lowers. Remain stopped until the gates go up and the lights stop flashing.

Explanation: Get out and away from the tracks, then call 911 or the emergency number posted at the crossing and give the location, including the DOT number if posted.

Explanation: Brakes that get too hot start to fade, so you must press harder and harder for the same stopping power. If you keep braking hard, they can fade until you cannot stop.

Explanation: Every brake must do its share. Brakes out of adjustment quit working first, leaving the others to overheat and fade, so check adjustment often.

Explanation: The old rule was to use the same gear down as up. Modern trucks have less friction and air drag, so they may need lower gears going down than going up.

Explanation: Brake hard enough to feel a definite slowdown until you are about 5 mph below your safe speed; this application should last about 3 seconds.

Explanation: Emergency steering and countersteering are two parts of one action. Be ready to turn back once you pass the obstacle, and do not brake while turning.

Explanation: Stab braking means braking fully, releasing when the wheels lock, and reapplying once they roll. It can only be done without ABS.

Explanation: With lost hydraulic pressure, downshift, pump the pedal, use the separate parking brake carefully, and look for an escape route.

Explanation: If ABS fails you still have normal brakes. Drive normally, but get the ABS serviced soon.

Explanation: In a front-wheel skid the front end keeps going straight no matter how you steer. Stop turning and braking so hard, and slow down without skidding.

Explanation: The first step is to keep another accident from happening there: move your vehicle aside if you can, turn on flashers and set out triangles.

Explanation: Do not move a severely injured person unless fire or traffic danger requires it. Stop heavy bleeding with direct pressure and keep the person warm.

Explanation: Get off the road and stop in an open area away from anything that might catch fire. Do not pull into a service station, and notify emergency services.

Explanation: Keep the van doors shut, especially with hazardous cargo. Opening them supplies oxygen and can make the fire burn very fast.

Explanation: Stay as far from the fire as possible, position yourself upwind, and aim at the source or base of the fire, not up in the flames.

Explanation: A burning tire must be cooled, and it may take a lot of water. Keep going until whatever was burning has cooled, since it can restart.

Explanation: Alcohol first affects judgment and self-control, which can keep drinkers from knowing they are getting drunk.

Explanation: Possession and use of a drug given by a doctor is allowed if the doctor says it will not affect safe driving. Watch warning labels on all medicines.

Explanation: A placarded vehicle needs at least 4 identical placards on the front, rear and both sides, readable from all four directions.

Explanation: Keep hazmat shipping papers in a pouch on the driver's door or in clear view within reach while driving, and on the driver's seat when you are out of the vehicle.

Explanation: Hazmat rules exist to contain the product, communicate the risk through papers, labels and placards, and ensure safe drivers and equipment.

Explanation: Class 3 covers flammable liquids such as gasoline and acetone. Class 8 corrosives include hydrochloric acid and battery fluid.

Explanation: Too little weight on the drive axles means poor traction and spinning wheels. Too much weight on the steering axle causes hard steering.

Explanation: Overloading the steering axle makes steering hard and can damage the axle and tires; underloading it makes the steering too light to steer safely.

Explanation: The combined working load limit of the tie-downs securing an article must be at least one-half times the weight of that article or group of articles.

Explanation: Covers protect people from spilled cargo and protect cargo from weather. Check covers in your mirrors, since a flapping cover can tear loose.

Explanation: You cannot inspect sealed loads, but you should check that you do not exceed gross weight and axle weight limits.

Explanation: Suspended meat can be very unstable with a high center of gravity, so go slowly on sharp curves such as off ramps and on ramps.

Explanation: Dry bulk tanks have a high center of gravity and a load that can shift, so be extremely cautious on curves and sharp turns.