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Practice test 4 of 10

North Carolina CDL — Air Brakes Practice Test 4

The North Carolina CDL — Air Brakes knowledge test has ~25 questions; you need ~20 correct (80%) to pass.

This practice test follows that format: 25 questions, pass with 20 correct. Answer every page, then grade it to see the answers and explanations.

Questions 1–10 of 25

  1. 1.What is the purpose of a modulating control valve?
  2. 2.According to the manual, what is the most common brake problem found during roadside inspections?
  3. 3.What should you conclude if the safety relief valve lets air escape?
  4. 4.The safety relief valve, mounted in the first reservoir the compressor fills, is usually set to open at what pressure?
  5. 5.Which type of foundation brake is the most common on air-brake vehicles?
  6. 6.If your tanks have manually operated drain valves rather than automatic ones, how often should you drain them?
  7. 7.How do you test that the parking brake will hold?
  8. 8.A visible low-air-pressure warning must come on before tank pressure drops below what level?
  9. 9.What causes brakes to fade?
  10. 10.During the final air-brake check on a dual system, with the engine at operating rpm, about how long should air pressure take to rise between the 85 and 100 psi marks?

0 of 25 answered