Idaho ITD CDL General Knowledge Practice Test 2
Test 2 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 Idaho test.
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
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1. Experienced commercial drivers scan the road ahead by roughly how much travel time?
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Answer B: About 12 to 15 seconds
Looking 12 to 15 seconds ahead gives a heavy vehicle enough room to slow or change lanes smoothly instead of reacting late.
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2. What is checked about the clutch and the gearshift during the in-cab inspection?
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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.
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3. A car that passed you on the right slows and stays alongside your trailer. What is the best response?
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Answer D: Ease off the accelerator so the car can move clear
A vehicle sitting beside a trailer is in a blind area and has nowhere to go if you need the lane, so the safest fix is to let it get ahead or behind.
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4. An enforcement officer inspects your vehicle at the roadside and attaches an out-of-service sticker. What may you do?
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Answer C: Nothing until the defect is repaired; the vehicle may not be driven
An out-of-service order means the vehicle is unsafe, and no schedule, load or destination allows it to be driven before the defect is corrected.
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5. What does the gross vehicle weight rating of a vehicle describe?
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Answer A: The maximum loaded weight of that single vehicle, as specified by the manufacturer
The rating is the manufacturer figure for the loaded weight of one vehicle, so it is a limit fixed in advance rather than a measurement of the load on board today.
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6. A hazard suddenly appears ahead and you must act. Which is usually the faster way to avoid it in a heavy vehicle?
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Answer B: Steering around it, because you can usually turn faster than you can stop
Stopping distance at speed is very long, so a quick turn out of the way, when there is room, avoids the crash sooner than braking.
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7. How does a load carried high in the trailer affect safe speed through a curve?
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Answer B: It raises the rollover risk, so the speed must be lower
A high center of gravity lets the vehicle tip long before the tires lose their grip, so height of the load directly limits curve speed.
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8. 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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9. 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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10. What actually lowers the amount of alcohol in the bloodstream?
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Answer B: Time
The liver removes alcohol at a fixed rate, so nothing but the passage of time reduces blood alcohol concentration.
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11. During the engine compartment check, which leaks are you looking for?
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Answer D: Fuel, coolant, engine oil, power steering fluid and battery fluid
Every fluid in the compartment matters, because a fuel leak is a fire risk and a loss of coolant, oil, steering fluid or electrolyte can disable the vehicle.
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12. How many questions are on the Idaho CDL Air Brakes knowledge test, and how many must be correct?
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Answer B: 25 questions, with 20 correct required
Idaho publishes the Air Brakes test as 25 questions with a minimum of 20 correct, while the Combination Vehicles and most endorsement tests are 20 questions with 16 correct.
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13. How does ITD classify talking on a hand-held mobile telephone while driving a commercial motor vehicle?
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Answer A: As a serious traffic violation
ITD lists texting or talking on a hand-held mobile telephone while driving a commercial motor vehicle among the serious traffic violations that can cost a driver their CDL privileges.
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14. What should you do before backing into a space you have not used before?
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Answer A: Get out and walk around to check the path, the clearance and any obstacles
Walking the area first reveals low obstructions, soft ground and objects that never appear in the mirrors.
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15. What speed and gear should be used when backing a large vehicle?
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Answer B: As slowly as possible, in the lowest reverse gear
Backing slowly in the lowest reverse gear keeps the vehicle under precise control and leaves time to correct the path.
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16. Your speedometer stops working during the pre-trip check. How should it be treated?
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Answer D: As a defect, because the driver cannot judge and control speed without it
A working speedometer is required equipment, because judging speed by feel in a heavy vehicle is unreliable and speed governs stopping distance.
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17. What are you looking for when you check the drive belts in the engine compartment?
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Answer C: That each belt is snug and free of cracks, frays or heavy wear
A loose or cracked belt can break and stop the fan, the water pump or the alternator, which leads quickly to overheating or a dead electrical system.
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18. 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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19. 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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20. 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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21. 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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22. What frame defects are you looking for during the walkaround?
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Answer A: Cracks, bends or broken cross members
The frame carries the whole load, so cracked or bent rails and broken cross members are serious structural defects.
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23. You are given a ratchet strap with a deep cut along one edge. What should you do?
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Answer C: Do not use it; a damaged tiedown cannot be relied on to hold its rated load
Cuts, burns, knots and broken stitching weaken a strap far below its marked working load limit, so it must be taken out of service.
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24. 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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25. Apart from the legal duty, what is the main practical reason for a thorough pre-trip inspection?
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Answer A: It finds problems that could cause a breakdown or a crash before the vehicle is on the road
A defect found in the yard is an inconvenience, while the same defect found at highway speed can be a crash, so the inspection is where problems are cheapest to fix.
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26. How can a driver restart the 60 or 70 hour on-duty limit?
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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.
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27. A sign before a long descent shows 6 percent. What does that number tell you?
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Answer A: How steep the grade ahead is
Percent grade is the drop in feet for every hundred feet of road, so the higher the number the faster speed will build and the lower the gear you need.
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28. A 40 foot straight truck and a 70 foot tractor-trailer make the same right turn. Which needs more room and why?
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Answer B: The tractor-trailer, because the longer the vehicle the farther inside the rear wheels track
Off-tracking grows with the distance between the front and rear axles, so the longer combination cuts the corner much more sharply and needs extra room.
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29. On a tractor with a sliding fifth wheel, what does moving the fifth wheel forward do?
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Answer A: Puts more of the trailer weight onto the steering axle
Moving the coupling point forward transfers weight from the drive axles to the steering axle, which is how a driver corrects a drive axle that is over the limit.
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30. A company mechanic serviced your truck this morning and signed the work order. Do you still have to inspect the vehicle?
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Answer B: Yes, the driver is still responsible for being satisfied the vehicle is safe
Shop work does not transfer the duty; the driver who takes the vehicle out remains responsible for being satisfied it is in safe operating condition.
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31. While checking the in-cab gauges after start-up, what should the coolant temperature gauge do?
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Answer C: Rise gradually to the normal operating range
A healthy cooling system warms the engine slowly; a gauge that shoots up or stays cold points to a problem with the thermostat, coolant or sensor.
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32. Which clues warn you that a parked car may pull out or open a door?
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Answer A: Exhaust smoke, turned front wheels, a person in the seat
Signs of life in a parked vehicle, such as a running engine, turned wheels or an occupant, mean it may move or open a door into your path.
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33. You must leave the vehicle parked on a slight grade. What adds security beyond setting the parking brake?
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Answer D: Chocking the wheels so the vehicle cannot roll if the brake bleeds off
Chocks hold the vehicle mechanically and are the standard backup whenever a parked vehicle could roll.
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34. At the scale your tractor drive axles are overweight while the trailer axles have room. Sliding the trailer tandems forward will do what?
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Answer C: Move weight off the drive axles and onto the trailer axles
Sliding the trailer tandems forward brings the rear support closer to the load, so the trailer axles pick up more weight and the drive axles carry less; sliding them rearward does the opposite.
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35. 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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36. 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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37. A fire starts in the cargo area of a van trailer. Why should you keep the doors closed until firefighters arrive?
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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.
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38. You are inspecting the vehicle alone and need to confirm that the stop lights work. Which method is correct?
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Answer A: Have a helper press the brake pedal, or apply the brake in a way that keeps it on while you check from outside
Stop lights are checked from outside the vehicle while the brakes are applied, so a helper or a brake held on is needed.
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39. Why is a sudden, sharp lane change dangerous in a loaded heavy vehicle?
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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.
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40. Why does a driver use pull-ups while backing into a tight space?
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Answer C: To pull forward and start the approach again when the angle is going wrong
Stopping, pulling ahead and repositioning fixes a bad angle safely, and there is nothing wrong with needing more than one attempt.
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41. An article of cargo has been blocked so that it cannot move forward. How many tiedowns does the federal rule call for?
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Answer A: One tiedown for every 10 feet of article length, or any part of that
Blocking against forward movement lowers the requirement to one tiedown per 10 feet of length or fraction of 10 feet.
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42. 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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43. 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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44. What information does an inspection decal on a commercial vehicle carry?
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Answer B: The date of the inspection, where the inspection report is kept, and information identifying the vehicle
The decal shows when the inspection was done, the name and address of the entity that holds the inspection report, and which vehicle it belongs to, so an officer can confirm the inspection at a glance.
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45. Where is a dunnage bag used and how does it work?
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Answer D: Between pieces of cargo inside a van, where it is inflated to take up the gap
A dunnage bag is placed in the void between loads and inflated so the cargo is wedged and cannot move as the vehicle rolls and brakes.
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46. What blood alcohol concentration disqualifies the holder of a commercial driver license who is operating a commercial vehicle?
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Answer D: 0.04 or higher
Commercial drivers are held to 0.04, half the limit that applies to a driver of a passenger car in the same state.
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47. Besides staying secure, cargo carried inside a vehicle must not do what?
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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.
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48. 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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49. What is required of the hooks, rails, rings and anchor points that tiedowns attach to?
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Answer A: They must be part of the vehicle and strong enough for the load being secured
A tiedown is only as strong as what it is hooked to, so anchor points must be proper vehicle fittings rated for the job.
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50. You normally pull an empty trailer, but today the same tractor is loaded to its legal maximum. What changes about getting under way?
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Answer A: You may need to start in a lower gear, since the load takes more pulling power
The heavier the load, the lower the gear needed to get the vehicle rolling without lugging or stalling the engine.