Texas DPS CDL General Knowledge Practice Test 9
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
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1. What are you looking for on the brake drums during the walkaround?
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Answer B: Cracks, dents and any oil or grease that has reached the friction surface
A cracked or badly scored drum can break apart under braking heat, and oil or grease on the friction surface destroys the braking effort at that wheel.
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2. 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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3. How do you confirm that the coupling is locked before pulling out of the yard?
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Answer D: By locking the trailer brakes and pulling gently forward against them
The tug test loads the coupling in the direction that would pull it apart, so if the jaws are not closed on the kingpin you find out at walking pace.
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4. How often must a Texas school bus operator transporting students pass the required physical and mental capability examination?
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Answer D: Every year
A person may not operate a school bus for students without passing an approved examination of mental and physical capability, and each school bus operator must pass it annually.
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5. 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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6. Where is the yellow antilock brake malfunction lamp on a trailer, and what does it mean if it stays lit?
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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.
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7. Part of looking well ahead is planning an out. What does that mean?
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Answer B: Keeping an escape path in mind in case traffic stops suddenly
Because a heavy vehicle often cannot stop in time, good drivers continuously note where they could steer if the space ahead closes.
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8. Where on a tire is tread depth measured?
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Answer C: In a major tread groove, away from any tie bar or wear indicator
Depth is taken in a major groove and away from the raised tie bars and wear indicators, which would give a shallower and misleading reading.
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9. 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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10. You are hauling an open box of loose gravel. What does that load require?
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Answer A: A cover, so that material cannot blow off or spill onto the road
Loose material that can be blown or spilled has to be covered so it does not come out of the body and strike traffic behind.
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11. In dense city traffic you cannot see 12 seconds ahead because other vehicles block the view. What is the best response?
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Answer A: Slow down and open up more space in front of you
When you cannot see far enough ahead, extra following distance buys back the reaction time that the blocked view has taken away.
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12. 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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13. How do you get more engine braking from an automatic transmission on a downgrade?
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Answer B: Select a lower range before starting down
Locking the transmission into a lower range keeps engine speed high enough to hold the vehicle back and spares the service brakes.
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14. You are dropping a loaded trailer in a yard. How far should the landing gear be lowered?
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Answer A: Until the pads make firm contact and the trailer weight is just off the fifth wheel
Cranking down until the gear is firmly on the ground and just lifting the load off the fifth wheel makes the trailer stable and lets the tractor pull out cleanly.
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15. A strap is a little too long, so a driver ties a knot in it to take up the slack. Is that acceptable?
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Answer C: No, tiedowns must not contain knots
A knot destroys the rated strength of a tiedown, so the rules do not allow knotted securement devices; the excess is taken up by the winch or ratchet instead.
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16. 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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17. An unblocked crate 4 feet long and weighing 900 pounds needs at least how many tiedowns?
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Answer D: One
An article 5 feet or less in length and 1,100 pounds or less in weight is covered by a minimum of one tiedown.
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18. 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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19. 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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20. What is the maximum length of a semitrailer in a Texas truck-tractor and semitrailer combination, excluding the towing device?
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Answer B: 59 feet
A semitrailer in a truck-tractor and semitrailer combination may not be longer than 59 feet, excluding the towing device, while trailers in a double combination are limited to 28 and a half feet.
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21. A car is following you far too closely. What is the safest response?
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Answer A: Open up more space ahead so you can slow gradually, avoid sudden changes, and do not speed up
Extra room in front lets you slow smoothly instead of braking hard, which is exactly what the driver behind cannot cope with.
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22. 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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23. Which wheel or rim condition must be treated as a defect during the walkaround?
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Answer C: Cracks, illegal welded repairs, or missing and loose lug nuts
Cracked or welded rims and missing or loose fasteners can let a wheel separate from the vehicle and must be corrected before driving.
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24. You are moving an oversized load under a permit that requires a pilot vehicle. What is the pilot vehicle there to do?
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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.
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25. 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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26. What is the first step of the standard seven-step vehicle inspection?
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Answer C: A general overview of the vehicle, including the last inspection report
The routine opens with a walk-up overview of the vehicle and a review of the previous inspection report so known defects are addressed first.
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27. 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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28. Why should a retarder be switched off when the road is wet, icy or snowy?
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Answer C: It can make the drive wheels skid when traction is poor
A retarder slows the drive wheels only, and on a slippery surface that braking force can break their traction and start a skid.
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29. Which components on a typical engine are driven by belts that must be checked for wear and tension?
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Answer D: The alternator, the water pump and, on many vehicles, the air compressor
Belts drive accessories such as the alternator, the water pump and the air compressor, so one failed belt can take out charging, cooling or air supply.
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30. 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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31. Rust streaks are running outward from the lug nuts on one wheel. What does this most likely indicate?
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Answer C: The lug nuts may be loose
Rust trails spreading from the nuts are a classic sign that the nuts have worked loose and the wheel has been moving on the studs.
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32. Your brakes are starting to fade on a mountain downgrade and a sign shows an escape ramp one mile ahead. What should you do?
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Answer B: Plan to use the ramp instead of trying to reach the bottom
Fading brakes on a grade only get worse, and the ramp exists precisely so a driver does not have to gamble on the rest of the descent.
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33. What can a Texas county commissioners court require of heavy vehicles with a gross weight above 60,000 pounds to protect county roads?
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Answer D: That they travel a designated route chosen to prevent road damage
Section 251.1575 allows a commissioners court to require heavy vehicles over 60,000 pounds gross weight to use an alternate route to prevent damage to county roads.
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34. 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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35. What should you check about the fuel tank during the walkaround?
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Answer A: That it is securely mounted, the cap is on tight and there are no leaks
A loose tank or a missing cap can spill fuel, and any fuel leak is a fire hazard that makes the vehicle unsafe to drive.
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36. Loading heavy freight on top of lighter freight has what effect on the vehicle?
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Answer B: It raises the center of gravity and makes a rollover more likely
A high center of gravity lets the vehicle tip more easily in curves or during a sudden swerve.
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37. Within total stopping distance, what exactly is perception distance?
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Answer D: The distance traveled from the moment your eyes see a hazard until your brain identifies it
Perception distance covers only the time between seeing a hazard and recognizing it as a hazard, before any physical reaction begins.
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38. 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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39. Why is braking while in a curve dangerous in a heavy vehicle?
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Answer A: The wheels lock more easily and the vehicle can skid
Tires already using their grip to turn have little left for braking, so hard braking in a curve locks the wheels; slow down before the curve instead.
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40. Which Texas commercial drivers can use the alternative visual acuity standard?
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Answer D: Only drivers who operate a commercial motor vehicle solely within Texas
Texas may apply the alternative federal visual acuity standard only to an applicant or holder who drives a commercial motor vehicle exclusively inside the state.
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41. 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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42. 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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43. 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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44. When does a Texas commercial learner permit expire?
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Answer A: Whichever comes first: the expiration date of the person's driver license, or the 181st day after the permit was issued
Texas Transportation Code Section 522.051(h) limits a commercial learner permit to the earlier of the underlying license's expiration date or the 181st day after the permit is issued.
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45. 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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46. Which of these counts as a serious traffic violation for a commercial driver license holder?
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Answer C: Speeding 15 miles per hour or more above the limit
Excessive speeding, reckless driving, improper lane changes, following too closely and texting while driving are all serious traffic violations.
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47. How can a driver tell that a shipment includes hazardous materials?
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Answer B: The shipping paper describes them and the packages carry hazard warning labels
Hazardous materials are identified on the shipping paper with their shipping name and hazard class, and the packages themselves carry labels showing the hazard.
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48. 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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49. 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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50. You have chosen 40 miles per hour as your safe speed for a downgrade. How should the brakes be used?
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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.