Illinois SOS CDL General Knowledge Practice Test 9
- Questions30
- Correct to pass24
- Passing score80%
- Minimum age18 years
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1. 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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2. Why must cargo also be held down against vertical movement and not only against sliding?
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Answer D: Because a load that bounces can jump the blocking and slacken its own tiedowns
Rough road makes an unrestrained article lift; every bounce lets it move a little and works the tiedowns loose until nothing is holding it.
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3. Which winter preparation matters most for keeping the road in view?
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Answer D: Working wipers, washer fluid and a working defroster
Slush and road spray coat the windshield within minutes in winter, so wipers, washer fluid and the defroster are what keep any view at all.
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4. What does mountain driving demand that flat country driving does not?
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Answer D: Lower gears and constant allowance for gravity
In the mountains gravity works for you on the climb and against you on the descent, so gear selection and speed control matter far more than on level road.
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5. 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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6. 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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7. Within what distance should high beams be lowered at night?
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Answer D: Within about 500 feet of an oncoming vehicle and within about 500 feet of a vehicle you are following
High beams blind other drivers at close range, so they are lowered at roughly the same distance whether the other vehicle is coming toward you or is ahead of you.
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8. When is tire pressure most accurately compared with the recommended figure?
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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.
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9. You have countersteered to correct a rear-wheel skid and the vehicle straightens out. What must you be ready for next?
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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.
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10. A straight truck has a long body behind the rear axle. What happens to that overhang in a sharp left turn?
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Answer D: It swings out to the right and can strike a vehicle or an object on that side
Body that hangs behind the rear axle swings the opposite way to the turn, so the tail of the truck sweeps out into the next lane or over the curb.
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11. 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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12. 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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13. Why does extra weight make a long downgrade more dangerous even when the brakes are in good order?
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Answer B: Gravity adds to the momentum and the brakes heat up faster
The heavier the vehicle, the more energy the brakes must turn into heat, and heat is exactly what makes brakes fade on a long descent.
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14. 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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15. How does overloading affect the way a vehicle drives?
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Answer C: It slows the vehicle on upgrades, makes stopping take longer and can overheat the brakes on downgrades
Extra weight demands more from the engine and the brakes, so the vehicle climbs slowly and needs much more distance to stop.
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16. What are you checking on the mud flaps during the walkaround?
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Answer C: That they are securely attached, not torn and not dragging on the ground
A flap that is torn or hanging loose stops shielding following traffic from spray and stones, and a dragging flap can catch and tear away on the road.
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17. You are strapping down a load with sharp metal edges on a flatbed. What should you use?
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Answer D: Edge protection between the strap and the sharp edges so the tiedown is not cut
Sharp edges cut or wear through a strap under tension, so edge protectors are required wherever a tiedown could be damaged.
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18. What happens when too much of the load sits over the steering axle?
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Answer D: The vehicle becomes hard to steer and the axle and its tires can be damaged
Weight beyond the front axle rating makes the steering heavy and can overload the axle and the tires carrying it.
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19. Your vehicle begins to hydroplane on a wet road. What should you do?
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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.
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20. 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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21. Under federal rules, what is required of a commercial driver who wants to use a mobile phone while driving?
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Answer B: The phone must be hands-free and started with no more than a single button press, and it must not be held
Federal rules ban texting and hand-held phone use while driving a commercial vehicle; reaching for, holding or dialing a phone is a violation.
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22. What is generally the safest speed in dense but freely moving highway traffic?
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Answer D: The speed of the traffic around you, up to the posted limit
Crashes rise with the difference between your speed and the traffic around you, so moving with the flow within the legal limit is safest.
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23. What does the working load limit stamped on a chain or strap describe?
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Answer B: The maximum load the device is rated to hold in normal use
The working load limit is the rated safe capacity for everyday use, deliberately set well below the force that would break the device.
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24. You are asked to drive a truck loaded with enough hazardous materials to require placards. What must you have?
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Answer C: A hazardous materials endorsement on your commercial driver license
Driving a vehicle that must be placarded requires the H endorsement, which involves a separate knowledge test and a security background check.
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25. What tells you that an air suspension bag has a problem?
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Answer B: The bag is leaking or damaged, or the vehicle sits unevenly on that side
An air bag that leaks or is cut lets that corner of the vehicle settle, which throws the load onto the other suspension parts and changes the ride height.
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26. Why is it harder to judge speed and distance at night?
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Answer C: You see much less detail and have fewer reference points
Darkness removes the visual references that the brain uses to estimate distance and closing speed, so drivers routinely misjudge both.
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27. What should the ammeter or voltmeter show once the engine is running?
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Answer D: A reading in the normal charging range
With the engine running, the alternator should be charging; a discharge reading or an abnormal charge level means an electrical fault.
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28. For a modern truck with low-friction parts and a streamlined shape, which gear should be used going down a grade?
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Answer D: A gear lower than the one needed to climb the same grade
Newer trucks roll more freely than older ones, so the old rule of using the climbing gear no longer holds; a lower gear is needed for enough engine braking.
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29. You are drifting in the lane, yawning constantly and cannot remember the last few miles. What is the only reliable cure?
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Answer C: Stopping in a safe place and sleeping
Those are classic drowsiness warning signs, and nothing except sleep repays the sleep the body is missing.
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30. 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.