Nebraska DMV CDL General Knowledge Practice Test 4
Test 4 of 5. Pick an answer for each question to see if it is right and why; your score appears at the end. You need 40 correct answers to pass, the same ratio as the real Nebraska test.
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
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1. Under federal rules, what happens to a commercial driver found with any detectable amount of alcohol while operating a commercial vehicle?
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Answer D: The driver is placed out of service for 24 hours
Any measurable alcohol takes a commercial driver off the road for 24 hours, and a concentration of 0.04 percent or more brings a disqualification.
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2. Under the federal air brake standard, the low air pressure warning must come on before reservoir pressure drops below what level?
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Answer A: Before pressure falls below 60 psi
Federal Motor Vehicle Safety Standard 121 requires the warning to operate while service reservoir pressure is still above 60 psi, which leaves enough air to bring the vehicle to a normal stop.
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3. What must the driver confirm about the required emergency equipment before a trip?
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Answer A: That it is in place, in working order and ready to be used
Federal rules require the driver to be satisfied that the emergency equipment is present and ready, because it is needed at the worst possible moment.
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4. What blood alcohol concentration is unlawful while operating a commercial motor vehicle in Nebraska?
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Answer A: .04 percent or higher
Nebraska sets .04 percent BAC as the unlawful level while operating a commercial motor vehicle, half the general limit for other drivers.
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5. You stop to check the load. Which set of things are you looking at?
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Answer C: Tight tiedowns, cargo that has not moved, secure doors and tarps still fastened
A cargo check covers the load and everything holding it: whether it has shifted, whether the devices are still tight, and whether doors and covers are still closed and fastened.
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6. What is checked about the engine cooling system during the engine compartment inspection?
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Answer C: That the coolant level is adequate and the radiator and hoses are not leaking
A low coolant level or a leaking hose leads to overheating, which can stop the vehicle in a place where stopping is dangerous.
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7. What does the tachometer on the dashboard of a heavy truck show?
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Answer D: How fast the engine is turning, in revolutions per minute
The tachometer reads engine speed in rpm, which is what a driver uses to judge shift points in a vehicle with a manual transmission.
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8. During a trip you stop for a break. Which items should you check before driving on?
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Answer B: Tires, wheels and rims, brakes, lights, reflectors, electrical connections and cargo securement
Critical items can change during a trip, so each stop is used to recheck the tires, wheels, brakes, lights, connections and cargo.
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9. Your brakes have failed and you decide to use the parking brake to slow down. Why should you hold the release button or lever while doing so?
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Answer D: So you can release the brake at once if the wheels lock and the vehicle starts to skid
The parking brake can lock the wheels; keeping your hand on the release lets you let go the moment a skid starts and regain control.
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10. In hazard perception, what counts as a hazard?
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Answer C: Any road user or condition that could become a danger
A hazard is anything with the potential to create danger, which is why drivers are taught to spot them early rather than react to emergencies.
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11. What is the payload of a truck?
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Answer C: The weight of the cargo the vehicle is carrying, that is the loaded weight less the empty weight
Payload is what is left of the legal or rated weight once the weight of the empty vehicle is taken off, and it is the weight of cargo that can be carried.
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12. A commercial driver is convicted of two serious traffic violations within three years. What is the result?
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Answer D: Disqualification for 60 days
Two serious traffic violations in a three year period bring a 60 day disqualification, and a third in the same period raises it to 120 days.
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13. A brake light lens is cracked and the lamp still lights. How should that be treated?
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Answer B: As a defect, because water can enter and the lamp can dim or fail
A cracked lens lets in water and dirt, which corrodes the socket and dulls the lamp, so it is reported before it becomes a dead brake light.
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14. An unblocked article is 8 feet long and weighs 900 pounds. How many tiedowns does the federal rule require?
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Answer B: Two
Only an article that is 5 feet or shorter and 1,100 pounds or lighter can be held with a single tiedown; anything longer than 5 feet needs at least two whatever it weighs.
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15. You have chosen 40 miles per hour as your safe speed for a downgrade. How should the brakes be used?
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Answer A: Brake firmly to about 35, release, and repeat at 40
Proper technique is firm application to about 5 miles per hour below the safe speed, then full release so the brakes cool before the next application.
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16. An oncoming vehicle drifts across the center line into your lane. What is usually the safest move?
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Answer C: Steer to the right, toward the shoulder if necessary
Moving right keeps you away from the drifting vehicle and off the oncoming side; the other driver may swerve back and hit you if you go left.
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17. A driver behind you wants to pass and you can see that the road ahead is clear. What should you do?
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Answer B: Do not signal the other driver to pass; let that driver decide when it is safe
Directing other drivers can cause a crash if you misjudge the gap, so leave the decision to the driver who is passing.
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18. What does gross vehicle weight mean, as opposed to gross vehicle weight rating?
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Answer B: The actual weight of the single vehicle plus everything it is carrying
Gross vehicle weight is what the vehicle actually weighs at that moment; the rating is the maximum the manufacturer allows it to weigh.
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19. What must be true of the person who performs the annual periodic inspection?
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Answer D: They must meet the federal qualification requirements for an inspector
The inspection has to be done by someone who meets the federal training and experience requirements for inspectors, whoever employs them.
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20. Part of your load stands high enough to hide a rear lamp or a reflector. What must be done?
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Answer B: The load must be moved or extra lamps fitted so the required lights can be seen
Required lamps and reflectors must remain visible; if the cargo blocks them, the load is rearranged or additional lamps are fitted so the vehicle can still be seen.
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21. How is the fluid level in an automatic transmission usually checked?
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Answer A: With the engine running, following the procedure in the operator manual
Most automatic transmissions are designed to be checked with the engine running, and the operator manual gives the exact conditions for that vehicle.
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22. Which lamp must make the rear registration plate legible after dark?
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Answer C: A white lamp that lights the plate
A white license plate lamp is required so the plate can be read at night, and a burned out one is a defect like any other lamp.
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23. How do objects appear in a convex mirror compared with a flat mirror?
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Answer B: Smaller and farther away than they really are, while a wider area is shown
A convex mirror shows a wider field but shrinks everything in it, so the driver must remember that vehicles are closer than they look.
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24. What does it mean to overdrive your headlights at night?
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Answer D: Driving so fast that you cannot stop within the distance lit by your headlights
You must be able to stop inside the distance you can see; at night that distance is limited by the headlights, so speed must be lowered to match.
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25. The rear wheels of your vehicle lock during braking and the rear starts to slide sideways. What should you do first?
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Answer A: Stop braking so the rear wheels can roll again, then steer quickly in the direction you want to go
Locked wheels have no side grip; releasing the brakes restores traction and then countersteering brings the vehicle back into line.
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26. What is the correct way to make a right turn in a long vehicle?
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Answer D: Keep the rear of the vehicle close to the curb and swing wide only as you complete the turn
Swinging left before a right turn invites another driver to move into the gap on your right, so any extra width is taken as the turn is finished.
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27. Why is a quick lane change particularly risky with a load of hanging meat or of livestock?
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Answer A: The load swings or leans and can keep pushing the trailer after you straighten out
A swinging or leaning load keeps moving after the vehicle has finished the maneuver, so its momentum acts on the trailer at the worst moment.
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28. Besides allowing the move at all, what does an oversize load permit usually set out?
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Answer C: The route to be followed, the hours of travel allowed and the warning equipment needed
Permits for oversize movements normally name the roads that may be used, restrict the times of travel, and list the flags, signs and escorts required.
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29. Why does a load of live animals need special attention?
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Answer D: The animals move and lean, so the center of gravity shifts and the vehicle can be pushed off balance in a turn
A live load will not stay where it is put, and that movement changes the balance of the vehicle exactly when a curve is loading it most.
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30. What should you do with the previous driver vehicle inspection report before starting your trip?
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Answer B: Review it and confirm that listed defects were certified as repaired or as not needing repair
Reviewing the last report and the carrier certification tells you whether reported defects have been corrected before you take the vehicle out.
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31. What is axle weight?
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Answer C: The weight carried to the ground by one axle or one set of axles
Axle weight describes how the load is shared among the axles that carry it to the road, not how much the whole vehicle weighs.
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32. Before starting a trip, what must the driver confirm about the weight of the loaded vehicle?
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Answer A: That it is within the legal gross and axle limits for the route being driven
Overweight vehicles brake poorly, damage tires and suspension components, and can be put out of service at a scale, so weight is checked before the wheels turn.
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33. Which windshield condition should be reported during the inspection?
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Answer B: Cracks or dirt that get in the way of your view of the road
The windshield must give a clear view; damage or grime in the driver line of sight is a safety defect.
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34. Below 40 mph, what following distance does the standard commercial rule of thumb call for?
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Answer C: One second for every 10 feet of vehicle length
The base rule allows one second of space for each 10 feet of vehicle length while speed stays under 40 mph.
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35. Two tires in a dual set have noticeably different diameters. Why is that a problem?
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Answer C: The larger tire carries more than its share of the load and can be overloaded
The taller tire touches the road first and takes most of the weight, so it runs overloaded and hot while the smaller one does little work.
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36. Which wheel or rim condition must be treated as a defect during the walkaround?
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Answer C: Cracks, illegal welded repairs, or missing and loose lug nuts
Cracked or welded rims and missing or loose fasteners can let a wheel separate from the vehicle and must be corrected before driving.
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37. May a Nebraska CDL holder enter a traffic diversion program to avoid a conviction for a moving violation?
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Answer B: No, a CDL holder may not use diversion for any traffic citation except a parking violation
Nebraska prohibits CDL holders from entering a traffic diversion program to avoid a conviction for any traffic citation other than a parking violation.
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38. Some commodities have their own detailed securement rules on top of the general ones. Which list is made up of such commodities?
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Answer C: Logs, metal coils, paper rolls, concrete pipe and crushed vehicles
The cargo securement rules add specific requirements for particular commodities, including logs, dressed lumber, metal coils, paper rolls, concrete pipe, intermodal containers, vehicles, crushed cars, roll on containers and large boulders.
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39. How far ahead can a driver see with low beams and with high beams?
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Answer C: About 250 feet with low beams and about 350 to 500 feet with high beams
Low beams reach roughly 250 feet and high beams roughly 350 to 500 feet, and speed at night has to stay inside the distance the lights really show.
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40. Total stopping distance is made up of which parts?
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Answer A: Perception distance, reaction distance and braking distance
The vehicle travels while the hazard is recognized, while the driver moves to the pedal, and again while the brakes slow the vehicle.
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41. What is the purpose of the torque rods or radius rods you check on the suspension?
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Answer A: They hold the axle in alignment with the frame under braking and acceleration
Torque rods resist the twisting and fore and aft forces on the axle, so a cracked or missing rod lets the axle move out of alignment.
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42. What is normally required in order to move an over-width or over-length load?
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Answer B: A special permit along with warning devices such as flags and signs
Oversize movements need a permit plus marking devices, and travel is often limited to certain hours or routes.
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43. Why must the steering wheel be moved only a small amount at a time while backing?
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Answer B: Because a small turn of the wheel produces a large change at the rear of the vehicle
In reverse, the effect of the steering is greatly magnified at the back of the vehicle, so a small correction is usually all that is needed.
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44. Why should a retarder be switched off when the road is wet, icy or snowy?
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Answer C: It can make the drive wheels skid when traction is poor
A retarder slows the drive wheels only, and on a slippery surface that braking force can break their traction and start a skid.
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45. At highway speed, looking 12 to 15 seconds ahead means looking about how far down the road?
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Answer B: About a quarter of a mile
Twelve to fifteen seconds of travel is roughly a quarter of a mile at highway speed, while the same amount of time is about one block in slow city traffic.
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46. When traction is poor, such as on packed snow, how should you speed up?
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Answer C: Very gradually, so the drive wheels do not spin
Gentle throttle keeps the drive wheels from breaking traction, because spinning wheels give up both grip and directional control.
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47. Why should the radio, the fan and other noisy equipment be switched off during a required stop at a railroad crossing?
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Answer C: So that an approaching train can be heard
The rules require the driver to look and listen along the track, and on a double track crossing a passing train can hide a second one, so hearing matters as much as seeing.
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48. On a scale, your loaded truck is well under the gross weight limit, but one axle is above the limit for that axle. What does this mean?
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Answer D: The vehicle is overloaded and the load must be shifted or reduced before you drive on
Each axle and axle group has its own limit and each must be respected; being under the gross limit does not excuse an overloaded axle.
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49. What is the driver responsible for when a load is covered with a tarp?
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Answer C: Fastening it so it cannot flap free, block a mirror, or come off in the wind
A tarp that works loose can tear away, block the driver view or the view of others, and become a hazard for the traffic behind.
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50. You are pulling away from a curb in a 65 foot combination. Besides traffic, what must you watch?
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Answer B: The trailer wheels, which stay close to the curb and can strike it or an object on it
Because of off-tracking, the rear wheels follow a tighter path than the front, so they stay near the curb while the cab is already out in the lane.