Nebraska DMV CDL General Knowledge Practice Test 10
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
-
1. The combined working load limit of the tiedowns on a load must equal at least what share of the cargo weight?
Show answer
Answer C: One half of the cargo weight
Federal securement rules set the aggregate working load limit at no less than half the weight of the article or group of articles being held.
-
2. With water standing on the road, hydroplaning can begin at speeds as low as what?
Show answer
Answer D: 30 mph
When enough water covers the surface, the tires can ride up on it and lose contact at speeds as low as 30 mph.
-
3. You drive a 40 foot straight truck at 50 miles per hour in good conditions. What following distance does the rule of thumb call for?
Show answer
Answer A: 5 seconds
One second for every 10 feet of vehicle length gives 4 seconds, and one extra second is added for speeds above 40 miles per hour.
-
4. What is the driver looking for when the exhaust system is inspected?
Show answer
Answer B: Loose, broken or missing pipes, brackets or clamps, and signs that exhaust is leaking
A loose or leaking exhaust system can send carbon monoxide into the cab and can put hot gas against parts that will burn.
-
5. Where are the OVERSIZE LOAD signs normally carried on a vehicle moving under such a permit?
Show answer
Answer A: On the front and the rear of the vehicle
The warning signs face the traffic that meets the load and the traffic that comes up behind it, so they go on the front and the rear.
-
6. When should a driver select the gear for a long, steep downgrade?
Show answer
Answer B: Before starting down the grade
The low gear has to be chosen before the descent, because a heavy vehicle gaining speed may refuse to shift down at all.
-
7. Why should you avoid using your lights to tell a following driver that it is safe to pass you?
Show answer
Answer B: You may misjudge the gap and the driver will act on your signal
The manual warns against signaling others to pass, because the responsibility for a head-on crash then rests on a judgment you could easily get wrong.
-
8. After starting a trip, when must a driver first re-inspect the cargo and the devices holding it?
Show answer
Answer A: Within the first 50 miles
Federal rules require a check of the load and its securement within the first 50 miles, because settling and vibration loosen straps and chains early in a trip.
-
9. The engine has overheated and you need to check the coolant. What is the safe procedure with a pressurized radiator cap?
Show answer
Answer A: Shut the engine off, let the system cool, protect your hands, turn the cap slowly to its first stop so pressure escapes, step back, then remove it
A hot pressurized system throws steam and boiling coolant out of the opening, so the pressure is released slowly and only after the engine has cooled.
-
10. You have countersteered to correct a rear-wheel skid and the vehicle straightens out. What must you be ready for next?
Show answer
Answer D: The vehicle may swing back the other way, so you must steer again to correct it
A vehicle coming out of a skid tends to overshoot and swing in the opposite direction, and the driver must be ready to countersteer a second time.
-
11. Why must the steering wheel be moved only a small amount at a time while backing?
Show answer
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.
-
12. The brake pedal goes to the floor in a vehicle with hydraulic brakes. What can you do to build some braking pressure?
Show answer
Answer B: Pump the brake pedal rapidly, which may bring back enough pressure to slow the vehicle
Pumping can restore some hydraulic pressure; along with downshifting and the parking brake it is one of the ways to stop when the pedal fails.
-
13. Around a tractor-trailer, where are the blind areas that other drivers most often sit in unseen?
Show answer
Answer A: Along the right side and directly behind the trailer
The blind areas to the right of the cab and behind the trailer are the largest, which is why other drivers should never linger there.
-
14. You are about to back across a quiet street into a driveway. Which of these is good practice before you start to move?
Show answer
Answer B: Turn on the four-way flashers and sound the horn to alert anyone nearby
Warning other road users and pedestrians before a reverse maneuver gives them the chance to stop or move clear before the vehicle starts back.
-
15. Why must a bent, cracked or badly seated lock ring be reported?
Show answer
Answer D: It can come off under pressure and let the tire and rim separate violently
The lock ring holds the assembly together against the full pressure of the tire, so a damaged ring can release with enough force to kill.
-
16. Why must exhaust components be checked for contact with other parts of the vehicle?
Show answer
Answer B: Hot exhaust parts touching fuel lines, tires or wiring can start a fire
Exhaust pipes run hot enough to ignite fuel and melt insulation, so they must be kept clear of the fuel system, the tires and the electrical harness.
-
17. A roadside test shows a commercial driver has measurable alcohol in the system but below 0.04. What happens?
Show answer
Answer C: The driver is placed out of service for 24 hours
Any measurable alcohol while on duty results in an immediate 24 hour out of service order, even when the concentration is under the 0.04 limit.
-
18. What is the driver responsible for when a load is covered with a tarp?
Show answer
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.
-
19. Some commodities have their own detailed securement rules on top of the general ones. Which list is made up of such commodities?
Show answer
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.
-
20. Why should both outside mirrors be checked over and over while backing?
Show answer
Answer B: Each mirror covers only part of the path and neither covers the blind spots, so people and objects can appear without warning
Working both mirrors in turn is the only way to follow the whole path of a vehicle you cannot see behind.
-
21. What is the main purpose of a retarder fitted to a heavy vehicle?
Show answer
Answer B: To help slow the vehicle and reduce the need to use the service brakes
Exhaust, engine, hydraulic and electric retarders all slow the vehicle so the brakes stay cool and wear less, especially on grades.
-
22. Why is a sudden, sharp lane change dangerous in a loaded heavy vehicle?
Show answer
Answer D: The vehicle can lean far enough to roll over, especially when the load sits high
A quick swerve throws the weight of a tall, heavy load sideways, and a rollover can begin before the tires ever slide.
-
23. When is tire pressure most accurately compared with the recommended figure?
Show answer
Answer B: When the tires are cold, before the vehicle has been driven
Recommended pressures are cold pressures, so a reading taken before the tires have heated up is the only one that can be compared directly.
-
24. Besides staying secure, cargo carried inside a vehicle must not do what?
Show answer
Answer C: Block the driver view or access to emergency equipment and exits
Cargo may not obstruct the view to the front or sides or prevent the driver from reaching emergency equipment and exits.
-
25. What is checked about the clutch and the gearshift during the in-cab inspection?
Show answer
Answer D: That the clutch free play is within the range the manufacturer specifies
Too little or too much clutch free play causes slipping or dragging, either of which can leave the driver unable to select the gear a hill demands.
-
26. Where is the yellow antilock brake malfunction lamp on a trailer, and what does it mean if it stays lit?
Show answer
Answer D: On the left side, at the front or rear corner, and it means the antilock function may not be working
Trailers carry the yellow lamp on the left side, and a lamp that stays on after the bulb check means the antilock function may be lost even though the normal brakes still work.
-
27. You press on a drive belt and it deflects far more than the others. What does that suggest?
Show answer
Answer C: The belt is too loose and the part it drives may not work properly
A belt with excessive play slips on its pulleys, so the accessory it drives turns too slowly or not at all under load.
-
28. How does a driver keep a vehicle with a manual transmission from rolling back when starting on an upgrade?
Show answer
Answer D: Partly engage the clutch before the right foot leaves the brake, or hold the vehicle with the parking brake until the engine pulls
Something has to hold the vehicle during the instant the foot moves from the brake to the accelerator, and that is either the clutch at its engagement point or the parking brake.
-
29. What should be done before a night trip to get the most from your headlights?
Show answer
Answer C: Clean the windshield, the mirrors and the lights
Dirt on glass and lenses cuts both the light you throw down the road and the light that reaches your eyes, so cleaning is the cheapest night safety measure there is.
-
30. When must a driver first inspect the cargo and its securement devices?
Show answer
Answer C: Before starting the trip, as part of the pre-trip inspection
Cargo is part of the pre-trip inspection; the later checks within 50 miles and every three hours or 150 miles come on top of that first inspection.
-
31. An oncoming vehicle at night has bright headlights that are making it hard to see. What should you do?
Show answer
Answer B: Look toward the right edge of your lane and avoid looking directly at the lights
Looking at the right edge of the road keeps your eyes off the glare while you stay in your lane; glare can leave you nearly blind for several seconds.
-
32. You are moving an oversized load under a permit that requires a pilot vehicle. What is the pilot vehicle there to do?
Show answer
Answer B: Warn other traffic and check the route ahead for clearances and hazards
Escort or pilot vehicles warn approaching traffic and scout the route for low bridges, narrow spots and other hazards that a wide or long load cannot pass.
-
33. At a rest area you find that the load has shifted although the straps still feel tight. What should you do?
Show answer
Answer C: Correct the load before driving on, since a shifted load is no longer secure
Movement means the securement has already failed once, and a load that has shifted can shift again, so it is put right before the vehicle moves.
-
34. Why is a leak in the exhaust system especially dangerous in cold weather?
Show answer
Answer A: Carbon monoxide can build up inside a closed cab
In winter the windows are shut and the heater is running, so exhaust gas that escapes early can reach the driver and cause drowsiness or worse.
-
35. Which vehicle is most likely to be pushed around by a strong crosswind?
Show answer
Answer B: An empty van trailer
A large flat side with very little weight behind it gives the wind the most surface and the least resistance, which is the empty van trailer.
-
36. A fire has started in the vehicle. How should the extinguisher be used?
Show answer
Answer B: Stay as far back as the reach of the extinguisher allows, stand upwind, and aim at the base of the fire
Aiming at the base attacks what is actually burning, and staying upwind and well back protects the driver from heat, smoke and the flames themselves.
-
37. What does it mean to overdrive your headlights at night?
Show answer
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.
-
38. What is the correct way to test the parking brake before a trip?
Show answer
Answer C: With the parking brake set, put the vehicle in a low gear and gently try to move forward
A parking brake that holds against a gentle pull in low gear is working; if the vehicle moves, the brake needs adjustment or repair.
-
39. What is the basic rule about backing a large vehicle?
Show answer
Answer B: Avoid backing whenever there is another way
Backing is dangerous because you cannot see everything behind you, so the manual tells drivers to plan routes and parking that avoid it.
-
40. How can a driver restart the 60 or 70 hour on-duty limit?
Show answer
Answer B: Take 34 or more consecutive hours off duty
A period of 34 or more consecutive hours off duty resets the 60 or 70 hour calculation so the driver can begin a new period.
-
41. At 55 mph on dry pavement with good brakes, total stopping distance for a loaded heavy vehicle is roughly what?
Show answer
Answer B: About 400 feet or more
Perception, reaction, and braking together add up to roughly 400 feet or more, farther than the length of a football field.
-
42. Your vehicle begins to hydroplane on a wet road. What should you do?
Show answer
Answer B: Release the accelerator and push in the clutch so the wheels can turn freely and regain grip
Hydroplaning tires are riding on water; slowing without braking lets them settle back onto the road and grip again.
-
43. A fire starts in the cargo area of a van trailer. Why should you keep the doors closed until firefighters arrive?
Show answer
Answer D: Opening the doors lets in air that feeds the fire
A fire in a closed van is starved of oxygen; opening the doors gives it the air it needs to flare up.
-
44. Compared with a fully loaded one, an empty truck under hard braking will often do what?
Show answer
Answer A: Need a longer distance to stop because traction is poor
Stiff suspension and little weight over the tires reduce grip, so the wheels lock early and the vehicle can take longer to stop.
-
45. When should a driver add space beyond the basic following distance rule?
Show answer
Answer D: On slippery roads and whenever visibility is poor
The seconds rule is a minimum for good conditions, so rain, snow, darkness and heavy traffic all call for more space than that.
-
46. What must be true of the trailer landing gear before you move off?
Show answer
Answer B: Fully raised, with the crank handle secured and no missing or damaged parts
Landing gear left part way down can strike a railway crossing or a ramp, and a loose crank handle can swing out into a passing vehicle.
-
47. Two tires in a dual set have noticeably different diameters. Why is that a problem?
Show answer
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.
-
48. You have chosen 40 miles per hour as your safe speed for a downgrade. How should the brakes be used?
Show answer
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.
-
49. On a set of dual tires, which condition must be reported as a defect?
Show answer
Answer D: The two tires are touching each other or rubbing on part of the vehicle
Duals that touch each other or the vehicle overheat and wear quickly, so they must be separated by proper spacing and inflation before driving.
-
50. You are on a freeway and see brake lights come on in several vehicles far ahead of you. What should you do?
Show answer
Answer A: Ease off the accelerator and get ready to slow down
Brake lights well ahead are an early warning that traffic is slowing, and acting on them gives a heavy vehicle the room it needs.