South Dakota DPS CDL General Knowledge Practice Test 7
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
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1. 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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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. Why is cargo often covered with a tarp?
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Answer C: To protect people from spilled cargo and to protect the cargo from weather
A cover keeps material from blowing or spilling onto the road and shields the load from rain and sun; it does not replace securement.
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4. How are the extra gears of a multi-speed rear axle or auxiliary transmission usually controlled?
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Answer D: With a selector knob or switch on the gearshift lever of the main transmission
A range selector on the shift lever lets the driver choose the extra gear range while shifting the main transmission.
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5. You find a defect during the pre-trip inspection. What must happen before the vehicle is driven?
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Answer C: It must be repaired, or the vehicle must not be driven
Writing a defect down does not make the vehicle safe; a defect that affects safe operation has to be corrected before the trip starts.
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6. Using the snub braking method on a downgrade, when does the driver release the brakes?
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Answer A: After speed has dropped about 5 mph below the safe speed
The driver brakes firmly to about 5 mph under the chosen safe speed, releases to let the brakes cool, then repeats when the safe speed returns.
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7. How should a driver use brakes fitted with an antilock system during an emergency stop?
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Answer C: Brake as usual and keep enough pressure to stay in control while steering around the hazard
The system only works when the brakes are applied hard enough for it to act, so the driver keeps pressure on and steers while the system prevents lockup.
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8. 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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9. You are about to slow down sharply on a highway to make a turn into a narrow driveway. How can you warn the drivers behind you?
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Answer C: Tap the brake pedal a few times so the brake lights flash before you slow down
A few light taps flash the brake lights and give following drivers an early warning that you are about to slow or stop.
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10. What is wrong with resting your foot on the clutch pedal between shifts?
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Answer B: It slowly wears the clutch out, because the pressure plate is never fully engaged
Any weight on the pedal partly disengages the clutch, so it slips and wears; the foot belongs off the pedal once the shift is finished.
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11. Who has the authority to set the maximum speed for heavy vehicles, such as those over 10,000 pounds gross weight, on South Dakota highways?
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Answer C: The Transportation Commission, through adopted rules
State law directs the Transportation Commission to adopt rules setting the maximum speed for heavy vehicles rather than fixing a single number in the statute itself.
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12. 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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13. 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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14. 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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15. You are hauling livestock and the trailer is only partly full. What should be done?
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Answer A: Use false bulkheads or partitions to keep the animals bunched together
Animals that can move around shift the center of gravity, so a partial load is bunched together with partitions to limit how far the weight can move.
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16. During a stop you find a package in the trailer leaking an unknown chemical. What should you do?
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Answer C: Keep clear, keep others away and get help without touching the package
A driver without the training and equipment does not handle a leak; the job is to protect people from the material and get qualified help to the scene.
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17. How does South Dakota extend the one-year CDL disqualification offenses when the violation happens while transporting placarded hazardous materials?
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Answer D: The disqualification period increases to three years
When a listed disqualifying offense occurs while the driver is hauling placarded hazardous material, the one-year disqualification becomes three years.
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18. What is the minimum age to obtain a South Dakota commercial driver license?
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Answer C: 18 years old
The Department of Public Safety requires every South Dakota CDL applicant to be at least 18 and to pass the general knowledge test, any specialized tests and a skills test.
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19. 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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20. You miss a gear while double clutching and the transmission is stuck in neutral. What should you do?
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Answer B: Return to neutral, release the clutch, bring engine speed to match road speed and try again
Forcing the lever damages the gears; matching the engine speed to the road speed lets the gear engage cleanly on the next try.
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21. 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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22. For an unblocked article longer than 10 feet, the minimum is two tiedowns plus how many more?
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Answer B: One more for every additional 10 feet of length or any part of 10 feet
Past the first 10 feet, one more tiedown is added for each additional 10 feet of length or any fraction of that distance.
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23. Which factors determine a safe speed for a long, steep downgrade?
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Answer C: The steepness and length of the grade, the weight of the vehicle and cargo, and the road and weather conditions
Gravity, weight and traction all decide how fast a heavy vehicle can safely descend, which is why signs often post lower speeds for trucks on grades.
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24. 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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25. 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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26. What is the minimum tread depth required in every major groove of a steering axle tire?
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Answer D: 4/32 inch
Federal rules set a higher tread minimum for front steering tires than for other positions because a steering tire failure is far harder to control.
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27. When must a post-trip inspection be made?
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Answer D: At the end of each day the driver operates the vehicle
The post-trip inspection closes out each driving day so that anything found is recorded before the vehicle is handed to the next driver.
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28. Which description matches controlled braking during an emergency stop?
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Answer D: Apply the brakes as hard as you can without locking the wheels and keep steering movements small
Controlled braking keeps the wheels rolling just short of lockup, which gives the shortest stop while you keep the ability to steer.
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29. 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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30. During the walkaround inspection, where does the driver normally start and how does the check proceed?
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Answer C: At the left front of the vehicle, working around it in a set order that returns to the cab
The walkaround follows the same route every time, starting at the left front and circling the vehicle, so that nothing is skipped when the driver is tired or rushed.
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31. Why should a driver avoid shifting gears in the middle of a turn at an intersection?
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Answer D: Shifting during the turn takes a hand off the wheel and can cost you control
Pick the gear before you begin turning; shifting in the turn removes a hand from the wheel and can interrupt power just when you need steady control.
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32. The combined working load limit of the tiedowns on a load must equal at least what share of the cargo weight?
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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.
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33. 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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34. 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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35. Where are the OVERSIZE LOAD signs normally carried on a vehicle moving under such a permit?
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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.
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36. At what time of day do drowsy driving crashes occur most often?
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Answer A: Between midnight and 6 a.m.
The body clock makes people sleepiest in the early morning hours, which is when most fatigue-related crashes happen.
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37. A dock crew loads all of the freight at the very back of a 48 foot van trailer. What are the two consequences?
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Answer A: The steering axle is relieved of weight and steering becomes light, and the trailer axles may go over the limit
Weight placed far to the rear lifts weight off the front of the combination, so the steering goes light while the trailer axles take too much of the load.
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38. A hard frost has left your vehicle covered in ice. What must be cleared before you drive?
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Answer D: The windshield, mirrors, lights and reflectors
You must be able to see out and other drivers must be able to see your lights and reflectors, so all of those surfaces have to be cleared.
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39. How do you test for leaks in a hydraulic brake system during the pre-trip inspection?
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Answer A: Pump the pedal three times, then hold firm pressure for five seconds and make sure the pedal does not move
If the pedal sinks while you hold pressure, fluid is escaping or air is in the lines, and the vehicle must not be driven until the problem is repaired.
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40. What must the driver check about the seat belt during the inspection?
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Answer A: That it is securely mounted, adjusts properly and is not ripped or frayed
A belt only restrains the driver if its anchorage is sound and the webbing is intact, so mounting and condition are both checked.
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41. You are loading a flatbed that has no sides or bulkheads. How must the cargo be held?
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Answer D: By tiedowns, blocking or bracing, since there are no walls to keep it from shifting or falling off
Open decks depend entirely on securement devices; every article must be tied down or otherwise immobilized so it cannot move, spill or fall.
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42. 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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43. After two hours of driving you measure a tire and the pressure reads higher than the cold figure. What should you do?
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Answer B: Nothing, because pressure rises normally as a tire heats up in use
Air expands as the tire heats, so a higher hot reading is expected, and letting air out leaves the tire underinflated once it cools.
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44. Besides slowing down, which technique most reduces the risk of a skid on a snow covered road?
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Answer B: Make every steering, braking and speed change gradual
Traction is limited on snow, and sudden inputs demand more grip than the surface can supply, so smoothness is what keeps the tires attached to the road.
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45. At 55 mph, about how far does a vehicle travel during a typical 3/4 second perception time plus 3/4 second reaction time, before the brakes even begin to work?
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Answer C: About 120 feet
Each 3/4 second at 55 mph covers about 60 feet, so perception and reaction together use up roughly 120 feet before braking starts.
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46. What should you check about the air hoses and the electrical cord running to the trailer?
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Answer D: That they are free of damage, properly connected and not dragging or rubbing
Lines that chafe on the frame or drag on the road wear through, and a broken line takes away trailer braking or trailer lighting without warning.
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47. Besides being uncomfortable, what can a series of hard, jerky brake applications do to a loaded combination?
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Answer A: Shift the load and push the trailer out of line behind the tractor
Sudden, uneven braking can move cargo forward and upset the alignment of a trailer, which is why stops should be made smoothly.
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48. 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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49. On a two lane road carrying traffic in both directions, where do the three warning devices go?
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Answer C: About 10 feet from the vehicle on the traffic side, 100 feet behind and 100 feet ahead
Traffic can approach from either direction, so one device goes close to the vehicle and one is placed about 100 feet away in each direction.
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50. 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.