Nevada DMV CDL General Knowledge Practice Test 5
Test 5 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 Nevada test.
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
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1. A dispatcher tells you to take a trailer you believe is loaded badly enough to be unsafe. What should you do?
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Answer C: Refuse to move it until the load has been made safe
The driver may not operate a vehicle whose cargo is not properly distributed and secured, and an instruction from an employer does not change that.
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2. While you are driving, what should you do to catch a developing problem with the vehicle?
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Answer A: Check the gauges regularly and pay attention to unusual sounds, smells or vibrations
Inspection continues during the trip: gauges, mirrors and your senses can reveal a problem long before a warning light does.
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3. A driver snores heavily, stops breathing briefly during the night and is tired all day despite long hours in bed. What should be suspected?
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Answer B: Sleep apnea
Sleep apnea repeatedly interrupts breathing during sleep, so the driver never gets true rest and stays dangerously drowsy during the day.
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4. In very hot weather, how often should you check the tires during a trip?
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Answer D: About every two hours or every 100 miles
Heat raises tire pressure and can lead to blowouts, so tires are checked about every two hours or 100 miles when it is very hot.
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5. Why must the downshift be finished before you reach a steep downgrade or a sharp curve rather than during it?
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Answer D: Because once your speed is too high you may not get into any gear at all
If you wait until speed has built up, the lower gear may refuse to engage and you can be left in neutral with no engine braking at all.
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6. How does the working load limit of a tiedown relate to the force that would break it?
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Answer B: The working load limit is a fraction of the breaking strength and is the figure you use
The working load limit is set well below the point at which the device would fail, and securement is always calculated from the working load limit, never from breaking strength.
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7. A tire has a cut deep enough to expose the body ply or the belt material. What does that mean?
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Answer D: The vehicle must not be driven on that tire
Once the structural plies are exposed the casing has lost its strength, and federal rules treat that tire as unfit for the road.
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8. How should the steering wheel be held when driving a large vehicle?
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Answer D: Firmly with both hands, placed on opposite sides of the wheel
Both hands on opposite sides give the leverage and control needed if a tire drops off the pavement or the wheel is jolted.
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9. You drop your phone on the floor of the cab while driving. What do federal rules require?
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Answer A: Leave it, because reaching for it while driving is banned
Federal rules forbid reaching for a mobile device in any way that takes the driver out of a seated, belted driving position.
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10. Which exhaust system condition must be reported as a defect?
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Answer B: A section repaired by wrapping tape or patching material around the pipe
Exhaust parts may not be patched with wrap or tape, because the repair does not contain the gas or the heat and it fails quickly in service.
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11. Which situations call for a mirror check in a commercial vehicle?
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Answer A: Every lane change, turn, merge and tight maneuver
Mirrors must be checked regularly and always before, during and after any movement that changes the path of the vehicle.
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12. A carrier operates commercial vehicles every day of the week. What weekly on-duty limit applies to its drivers?
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Answer A: 70 hours in 8 consecutive days
The limit is 60 hours in 7 consecutive days for a carrier that does not run every day, and 70 hours in 8 consecutive days for one that does.
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13. What should you check about the tire valve stems during the walkaround?
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Answer D: That the stems are not cut, cracked or leaking and the caps are in place
A split stem or a missing cap lets air escape or lets dirt into the valve, and either one can flatten a tire between stops.
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14. What is the minimum tread depth for tires in positions other than the steering axle?
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Answer A: 2/32 inch
Drive and trailer tires must keep at least 2/32 inch of tread in a major groove, measured away from tie bars and fillets.
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15. You are pulling a loaded pneumatic dry bulk trailer and approach an exit ramp posted at 35 mph. What is the safest approach?
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Answer C: Slow to well below the posted speed before the ramp begins
A dry bulk trailer carries its weight high and the load can move, so the ramp speed posted for a car is far too fast and the slowing must be finished before the curve.
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16. How is free play in the steering wheel measured during the inspection?
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Answer B: By turning the wheel until the front wheels just start to move and noting the movement
Play is the movement at the rim that produces no movement at the road wheels, so it is measured by turning until the wheels first respond.
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17. Why should a driver avoid traveling alongside another vehicle for any length of time?
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Answer D: You lose your escape route and you may be sitting in the other driver blind spot
Running beside someone leaves nowhere to move if you have to change lanes, and the other driver may not know you are there at all.
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18. Does the federal texting ban apply to a company dispatching device mounted in the cab?
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Answer B: Yes, entering or reading text on it while driving is banned
The rule is written around the act of reading or entering text on any electronic device, not around who owns the device.
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19. Where should a trailer be dropped, and what else does the driver do before pulling out from under it?
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Answer C: On solid level ground, with the trailer wheels chocked if it may roll
A dropped trailer must sit on ground that will carry the landing gear without sinking, and chocks stop it rolling once the tractor and its air supply are gone.
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20. During uncoupling, when may the fifth wheel locking lever be released?
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Answer D: Only after the landing gear is down and taking the weight of the trailer
The landing gear has to be supporting the trailer before the lock is released; otherwise the trailer nose can drop as soon as the tractor pulls out.
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21. A tire may be regrooved only when what is true?
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Answer B: It carries a marking from the manufacturer showing that it is regroovable
Only casings built with extra rubber under the tread and marked regroovable by the manufacturer may be cut, because others would be grooved into the belts.
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22. What extinguisher rating is required on a vehicle carrying hazardous materials in amounts that need placards?
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Answer B: 10 B:C or more
Placarded loads carry a much higher fire risk, so the required extinguisher rating rises to at least 10 B:C.
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23. What can repeated violations of the federal phone and texting rules cost a commercial driver?
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Answer D: Disqualification of the commercial driver license
Multiple convictions for using a hand-held phone or texting while driving a commercial vehicle lead to disqualification, on top of fines for driver and carrier.
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24. Regular mirror checks during a long trip can reveal which developing problem?
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Answer D: Smoke coming from a tire or from a wheel
Overheating tires, wheel bearings and brakes usually show as smoke long before anything appears on the dash, and mirrors are where a driver sees it.
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25. Why should high beams not be used in fog?
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Answer A: The light reflects back off the droplets and blinds you
Fog is made of water droplets that scatter light straight back at the driver, so a stronger beam makes the wall of glare worse rather than better.
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26. How long is a Nevada Commercial Learner Permit valid?
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Answer D: 180 days
Nevada issues Commercial Learner Permits valid for 180 days, and a permit expired for 30 days or more forces the applicant to retake all applicable knowledge tests.
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27. A chain rated at 6,600 pounds is fitted with a hook rated at 4,700 pounds. What is the working load limit of that assembly?
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Answer A: 4,700 pounds, the rating of the weakest part
An assembly is only as strong as its weakest component, so hooks, binders and links all count and the lowest rating governs.
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28. Why should water never be used on an electrical fire or a gasoline fire?
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Answer C: It spreads the fuel and conducts the current
Water carries current back to the person holding the hose and floats burning fuel outward, which is why a B:C rated extinguisher is carried instead.
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29. What do you check about the fire extinguisher during the pre-trip?
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Answer C: That it is securely mounted, charged and that you know how to operate it
An extinguisher must be held in its bracket, show a charged gauge and be understood by the driver, because a fire leaves no time to learn.
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30. What must be true of the trailer landing gear before you move off?
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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.
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31. You can see a crack in a brake drum that runs across more than half the width of the friction surface. What does this mean?
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Answer C: The drum is defective and must be repaired before the vehicle is driven
Cracks longer than half the width of the friction area mean the drum can break apart under braking heat and must be replaced.
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32. How does bracing differ from blocking when securing cargo?
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Answer B: Bracing runs from the upper part of the cargo to the floor or walls to keep it from moving, while blocking fits snugly against the cargo
Blocking is shaped to fit against the front, back or sides of a piece of cargo; bracing supports it from above so it cannot tip or shift.
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33. What is the purpose of the header board, or headache rack, that you inspect behind the cab?
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Answer A: It protects the driver from cargo that shifts forward during a hard stop
In a hard stop the load keeps moving forward, and the header board is the barrier between that load and the back of the cab.
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34. Why must you never coast down a hill in neutral or with the clutch pushed in?
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Answer C: You lose the braking effect of the engine and your brakes may overheat and fail
Engine braking is what keeps a heavy vehicle in check on a grade; coasting throws it away and leaves the service brakes to do all the work until they overheat.
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35. A load overhangs the rear of the trailer. What must the driver check before leaving?
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Answer D: That the overhang is marked as required, with flags or lamps as conditions demand
A projecting load has to be made visible to other drivers, with flags in daylight and lamps when lights are required, so nobody runs into what they cannot see.
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36. The coolant temperature gauge climbs above its normal range on a long grade. What is the correct response?
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Answer C: Stop when it is safe to do so and find the cause before going on
Rising coolant temperature signals a fault such as a lost belt, a leak or a blocked radiator, and continuing can turn a repair into a destroyed engine.
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37. Why does a heavy vehicle need a much larger gap than a car in order to cross or enter traffic?
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Answer C: Because it accelerates slowly and needs far more road and time to clear the intersection
Slow acceleration combined with the length of the vehicle means a gap that would feel comfortable in a car is nowhere near enough.
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38. Why should you avoid using your lights to tell a following driver that it is safe to pass you?
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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.
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39. What alcohol concentration triggers the 185-day administrative revocation for the holder of a Nevada commercial driver license?
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Answer B: .04 percent or more
Nevada's administrative action revokes the license for 185 days at .08 percent for ordinary drivers, but at .04 percent or more for a commercial driver license holder.
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40. As a long vehicle goes around a corner, how do the rear wheels travel compared with the front wheels?
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Answer A: They follow a tighter path, closer to the inside of the turn
The rear wheels off-track toward the inside of the turn, and the longer the vehicle the bigger the difference, which is why the front must swing wide enough to keep the rear off the curb.
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41. Why must a bent, cracked or badly seated lock ring be reported?
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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.
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42. You are driving past a park where children are playing close to the curb. What is the correct assumption?
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Answer A: A child may run into the street without looking
Children act on impulse and do not judge traffic well, so a driver has to expect one to enter the road and slow down in advance.
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43. Federal rules keep recapped and retreaded tires off the front wheels of which vehicle?
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Answer B: Any bus carrying passengers
The federal rule names buses: a bus may not run with regrooved, recapped or retreaded tires on its front wheels, because a steer tire failure with passengers aboard takes away steering control.
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44. You must steer hard around an obstacle at highway speed. What is the correct technique?
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Answer B: Avoid braking while turning, turn only as far as needed, and countersteer as soon as the obstacle is passed
Braking during a hard steering input can lock the wheels and start a skid, and turning back at once keeps the vehicle from running off the far side of the road.
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45. 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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46. What should be done before a night trip to get the most from your headlights?
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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.
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47. How do you avoid the sharp lurch that comes at the very end of a stop in a heavy vehicle?
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Answer A: Ease off the brake pressure just before the vehicle actually comes to rest
A smooth stop is finished by reducing pedal pressure as the vehicle settles, so the suspension does not rock the cab and the load forward.
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48. Why should you never shift gears while crossing railroad tracks?
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Answer A: You could miss the gear or stall and be stuck on the tracks
A stalled or coasting vehicle on the tracks has no way to clear quickly, so choose the gear before the crossing and do not shift until you are across.
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49. The car in the next lane still has snow covering most of its windows. What should you assume?
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Answer C: That driver cannot see you and may move into your lane
A driver whose view is blocked cannot see the vehicles around, so you should assume you are invisible and stay out of that vehicle path.
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50. What happens to braking distance when speed is doubled?
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Answer C: It becomes about four times longer
Braking distance grows with the square of speed, so doubling the speed multiplies both the braking distance and the force of an impact by about four.