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Stuff Every CDL Driver Should Know

CDL permit prep: General Knowledge, Air Brakes and the Hazmat endorsement, from the state CDL manual.

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  1. Which CDL class do you need for a combination over 26,000 lbs towing a trailer over 10,000 lbs?
    Show the answer

    Class A. Group A covers combinations with a gross combination weight rating of 26,001 lbs or more when the towed unit is rated over 10,000 lbs. A typical tractor-trailer needs a Class A.

  2. A single truck rated 26,001 lbs or more, towing nothing over 10,000 lbs, needs which CDL class?
    Show the answer

    Class B. Group B is any single vehicle with a GVWR of 26,001 lbs or more. It may tow a trailer, but only one rated 10,000 lbs or less. Dump trucks and big box trucks are typical Class B vehicles.

  3. A smaller vehicle needs a Class C CDL when it carries hazmat that needs placards or how many people?
    Show the answer

    16 or more, counting the driver. Class C covers vehicles too light for Class A or B that are designed to carry 16 or more people including the driver, or that haul hazardous materials. Many church and hotel shuttle buses fall here.

All 124 practice questions

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  1. Which CDL class do you need for a combination over 26,000 lbs towing a trailer over 10,000 lbs?
  2. A single truck rated 26,001 lbs or more, towing nothing over 10,000 lbs, needs which CDL class?
  3. A smaller vehicle needs a Class C CDL when it carries hazmat that needs placards or how many people?
  4. If you hold a Class A CDL, can you also drive Class B and C vehicles?
  5. Which CDL endorsement letter lets you pull double or triple trailers?
  6. Which CDL endorsement letter is for tank vehicles?
  7. What does the X endorsement on a CDL stand for?
  8. Which CDL endorsement needs both a knowledge test and a skills test?
  9. What happens if you fail the air brake knowledge test or take your skills test in a truck without air brakes?
  10. If you take the CDL skills test in a truck with an automatic transmission, what goes on your license?
  11. What is the minimum age to hold a commercial learner's permit (CLP)?
  12. Which endorsements are the only ones allowed on a commercial learner's permit?
  13. When a CLP holder drives a truck, where must the supervising CDL holder be?
  14. After you first get your CLP, how long must you wait before taking the CDL skills test?
  15. How long can a CLP be valid before you must retake the knowledge tests?
  16. First-time Class A and B applicants must finish entry-level training from whom?
  17. What blood alcohol level is illegal for someone driving a commercial motor vehicle?
  18. A CMV driver has a detectable amount of alcohol, but under 0.04. What happens?
  19. How many hours before going on duty is a CMV driver banned from using alcohol?
  20. What is the minimum CDL disqualification for a first refusal to take an alcohol test?
  21. A major offense, like leaving the scene of an accident, happens while hauling placarded hazmat. What is the first-offense disqualification?
  22. What happens to a CDL holder convicted of a second major offense, like two alcohol violations?
  23. Speeding counts as a serious traffic violation for CDL holders at how many mph over the limit?
  24. How long do you lose your CDL for two serious traffic violations in a CMV within 3 years?
  25. What is the minimum CDL disqualification for a first railroad crossing violation?
  26. Under CDL rules, which of these is a railroad crossing offense for all drivers?
  27. What is the minimum federal disqualification for a first out-of-service order violation hauling non-hazardous freight?
  28. What is the longest a regular DOT medical examiner's certificate can be valid?
  29. A driver whose diabetes is treated with insulin must be medically recertified how often?
  30. A property-carrying driver may drive a total of how many hours within the 14-hour window?
  31. After coming on duty following 10 hours off, a truck driver may not drive after how many consecutive hours?
  32. A truck driver needs a 30-minute break after how many hours of driving time?
  33. If your carrier runs trucks every day of the week, what is your on-duty limit?
  34. How many consecutive hours off duty restart a truck driver's 60/70 hour clock?
  35. A bus driver carrying passengers may drive up to how many hours after 8 hours off duty?
  36. In the CDL 7-step inspection method, what is Step 1?
  37. To test hydraulic brakes for leaks, you pump the pedal 3 times, then hold firm pressure for how long?
  38. What is the minimum tread depth for front (steering) tires on a commercial vehicle?
  39. How much steering wheel free play is too much on a commercial vehicle?
  40. How do you test the parking brake during a pre-trip inspection?
  41. When must a driver prepare a written vehicle inspection report on each vehicle driven?
  42. Before driving, when must you sign the previous driver's inspection report?
  43. How many red reflective warning triangles should be in a commercial vehicle's emergency equipment?
  44. During a trip, which is one of the critical items to check whenever you stop?
  45. How far ahead should a CDL driver scan the road ahead?
  46. How often does the CDL manual say to check your mirrors?
  47. What are the three parts of total stopping distance?
  48. If you double your speed from 20 to 40 mph, what happens to braking distance?
  49. What is the basic CDL following distance rule for speeds under 40 mph?
  50. For a 40-foot vehicle at 55 mph, what following distance should you leave?
  51. When you plan to turn or change lanes in a large truck, what should you do early?
  52. When should you use four-way flashers on a commercial vehicle?
  53. According to federal rules, what must a CDL driver do in snow, ice, fog, or smoke?
  54. On a wet road, about how much does the CDL manual say to reduce speed?
  55. When meeting an oncoming vehicle at night, dim high beams within what distance?
  56. What does it mean to avoid overdriving your headlights?
  57. Which headlight setting should a CDL driver use in fog?
  58. If the road surface is icy, what does the CDL manual say to do?
  59. In very hot weather, how often should you inspect your tires?
  60. What gear should you use before starting down a long mountain grade?
  61. What happens when a truck's brakes fade on a long downgrade?
  62. What is an escape ramp on a mountain highway used for?
  63. When a CDL vehicle must stop at a railroad crossing, where must it stop?
  64. Should a CDL driver shift gears while crossing railroad tracks?
  65. About how long does a typical tractor-trailer need to clear a single railroad track?
  66. Under federal rules, may a CMV driver text while stopped at a red light?
  67. When may a CMV driver use a hand-held mobile telephone while driving?
  68. According to the CDL manual, which kind of distraction is the most dangerous?
  69. When making a quick turn to avoid a hazard, what should you NOT do?
  70. How does the CDL manual say to brake a vehicle that has ABS?
  71. If your drive wheels start to spin from too much power, what should you do?
  72. What helps stop a jackknife when the trailer swings out?
  73. With an engine fire, what does the CDL manual say about the hood?
  74. What is the only real cure for driver fatigue?
  75. What must a driver do with cargo before driving?
  76. Under federal rules, tiedowns must have total working load limits of at least what?
  77. After starting a trip, when must a truck driver first inspect cargo securement?
  78. Where should the heaviest cargo go to keep a truck stable?
  79. What does GVWR mean on a commercial vehicle?
  80. Of all the space around a truck, which does the CDL manual call most important?
  81. In CDL terms, what is a hazard?
  82. After a turn, what should a CDL driver do with a turn signal that does not cancel itself?
  83. After a train passes at a crossing with multiple tracks, what must you check?
  84. Why should a truck driver carry tire chains in winter?
  85. Air brakes on a truck are really how many different braking systems?
  86. What does the air compressor governor do when tank pressure reaches cut-out?
  87. At about what tank pressure does the governor let the air compressor start pumping again?
  88. The air brake safety relief valve is usually set to open at what pressure?
  89. Why must you drain the air tanks on an air brake vehicle?
  90. What does an alcohol evaporator in an air brake system do?
  91. The low air pressure warning must come on before tank pressure drops below what?
  92. As air pressure drops, at what range do tractor spring brakes come fully on?
  93. The low air pressure warning comes on while you are driving. What should you do?
  94. On newer trucks, what does the parking brake control look like?
  95. Why should you never push the brake pedal down when the spring brakes are on?
  96. In the applied leakage test, how much air may a combination vehicle lose in one minute?
  97. In a dual air system, pressure should build from 85 to 100 psi within how long?
  98. What is brake lag on an air brake vehicle?
  99. In stab braking, when do you release the brakes?
  100. In the right low gear on a long downgrade, when do you release the brakes?
  101. How many hazard classes are hazardous materials sorted into?
  102. What kind of hazardous material is Class 2?
  103. Table 2 hazmat needs placards when the total amount reaches how much?
  104. How many identical placards must a placarded vehicle display?
  105. When do Placard Table 1 materials need placards?
  106. While you drive, where must hazmat shipping papers be?
  107. What must hazmat shipping papers list so responders can get expert help?
  108. The Emergency Response Guidebook (ERG) is indexed by what?
  109. Hazmat ID numbers on placards or orange panels have how many digits?
  110. Which part of the rules lists hazmat that must not be loaded together?
  111. With no cylinder racks, how must compressed gas cylinders ride?
  112. Hauling Division 1.1 explosives, how close to a tunnel or bridge may you park?
  113. When your truck is placarded, what should you avoid when choosing a route?
  114. If you are not in your parked placarded truck, how close must you stay to attend it?
  115. You may not smoke within how many feet of a vehicle carrying explosives?
  116. You think your cargo may be on fire. What should you do before opening the trailer doors?
  117. How should you identify a hazardous material leaking from your truck?
  118. Pulling hard on a slack adjuster, how much movement means it probably needs adjusting?
  119. What color is the ABS malfunction lamp on trucks and trailers?
  120. How often must hazmat employees be trained and tested?
  121. Who must label hazmat packages, prepare shipping papers and supply placards?
  122. What do baffles inside a liquid tank help control?
  123. Why do most heavy trucks use a dual air brake system?
  124. When should you NOT set the parking brakes?