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CDL General Knowledge Test practice questions

237 free questions with answers and explanations.

Practice test
  1. 201.A driver is performing a pre-trip inspection on a vehicle with air brakes. They notice that one of the brake chambers has a slight indentation or 'dishing' on the diaphragm housing. What is the most likely cause of this condition?Air Brakes (if applicable)
  2. 202.A driver is conducting a pre-trip inspection on a vehicle equipped with air brakes. They notice that when the air pressure drops below 60 psi, the low air pressure warning light and buzzer activate, but they do not deactivate until the pressure reaches 85 psi. What is the most likely cause of this discrepancy?Air Brakes (if applicable)
  3. 203.A truck driver is performing a pre-trip inspection. They notice that when the brake pedal is fully depressed, the pushrod on a service brake chamber moves less than 1 inch. The brakes appear to be working. What is the most likely implication of this observation?Air Brakes (if applicable)
  4. 204.A commercial vehicle with air brakes has just been started. The driver notices that the air pressure gauges are slowly rising, but the low air pressure warning light and buzzer remain active. At what minimum air pressure PSI should these warnings deactivate?Air Brakes (if applicable)
  5. 205.While operating a commercial vehicle, a driver notices that the air pressure in the secondary (front axle) air tank is significantly lower than the primary (rear axle) air tank, despite the compressor running normally. What is the most probable cause?Air Brakes (if applicable)
  6. 206.A driver is performing a final air brake check before starting a trip. They engage the parking brake and then release it, noting that the parking brake knob pops out. What does this indicate?Air Brakes (if applicable)
  7. 207.A driver is inspecting the brake drums on a vehicle with air brakes. They notice a significant amount of grease and oil on the inside surface of the brake drum. What is the most significant safety concern posed by this condition?Air Brakes (if applicable)
  8. 208.A driver is conducting a static air brake leakage test. After building full air pressure, shutting off the engine, and releasing the parking brake, the pressure drops by 5 psi in one minute. The vehicle is a single unit truck. What does this indicate?Air Brakes (if applicable)
  9. 209.A driver is inspecting the air brake system. They notice that the air compressor's automatic cut-out pressure is 135 psi, which is higher than the typical 125 psi. What is the potential consequence of this condition?Air Brakes (if applicable)
  10. 210.A commercial vehicle is equipped with a spring parking brake. If the air pressure in the system drops below approximately 20-45 psi, what will happen automatically?Air Brakes (if applicable)
  11. 211.A driver hears a continuous air leak coming from the foundation brake components (e.g., brake chamber) when the service brakes are applied. What does this most likely indicate?Air Brakes (if applicable)
  12. 212.During a pre-trip inspection, a driver observes that the air pressure gauge does not rise above 90 psi, even after several minutes of the engine running at operating RPM. The low air pressure warning light is illuminated. What is the most probable cause?Air Brakes (if applicable)
  13. 213.A driver is performing a brake check after completing a repair on an air brake system. With the engine off and the parking brake released, they apply the service brake pedal and hold it down. The air pressure gauge drops from 100 PSI to 95 PSI in one minute. What does this indicate for a single vehicle?Air Brakes (if applicable)
  14. 214.When inspecting a dual air brake system, a driver should ensure that the air pressure in both the primary and secondary systems builds from 85 psi to 100 psi within how many seconds at normal engine idle?Air Brakes (if applicable)
  15. 215.When inspecting the air brake system, a driver should check that the brake pedal has no more than approximately how much free play before the brakes begin to engage?Air Brakes (if applicable)
  16. 216.A technician is troubleshooting an air brake system. They find that the brake pedal feels spongy and requires significantly more travel than usual before the brakes engage. What is the most probable cause?Air Brakes (if applicable)
  17. 217.A driver is inspecting the brake drums on an air brake equipped vehicle. Which of the following conditions indicates a problem that requires immediate attention?Air Brakes (if applicable)
  18. 218.A driver notices that the air compressor cycles on and off more frequently than usual. During a pre-trip inspection, they find that the air pressure in the primary tank drops from 125 psi to 100 psi in 3 minutes with the engine off and the brakes applied. Which of the following is the most likely cause of this issue?Air Brakes (if applicable)
  19. 219.Which component of an air brake system is responsible for removing moisture and oil from the compressed air before it enters the air tanks?Air Brakes (if applicable)
  20. 220.During a pre-trip inspection, a driver checks the brake linings on a vehicle with air brakes. Which of the following conditions would indicate that the brake linings need to be replaced?Air Brakes (if applicable)
  21. 221.A driver is performing an emergency stop in a commercial vehicle equipped with ABS air brakes on a slippery road. What is the most appropriate braking technique to maintain control?Air Brakes (if applicable)
  22. 222.During a road test, a driver notices that when the service brakes are applied, the vehicle pulls sharply to one side. All tires are properly inflated. What is the most probable cause related to the air brake system?Air Brakes (if applicable)
  23. 223.A driver is performing a pre-trip inspection on a vehicle equipped with air brakes. They notice that when the brake pedal is fully depressed, the air pressure gauge drops from 120 psi to 80 psi. What is the most likely cause of this significant pressure drop?Air Brakes (if applicable)
  24. 224.A driver is transporting a load of empty barrels that are stacked two high on a flatbed trailer. The barrels are not interlocked. What is the minimum number of tiedowns required for this load, assuming the load is 20 feet long?Transporting Cargo Safely
  25. 225.What is the primary function of dunnage when used in cargo securement?Transporting Cargo Safely
  26. 226.A driver is transporting a load of logs that are 15 feet long and are contained within bunks or cradles. According to federal regulations, what is the minimum number of tiedowns required for this load?Transporting Cargo Safely
  27. 227.A technician is troubleshooting a vehicle with air brakes. They find that the parking brake will not release, even though there is sufficient air pressure in the system. Which component is the most likely cause of this issue?Air Brakes (if applicable)
  28. 228.When securing a load of large, heavy machinery that has a high center of gravity, which of the following securement methods is most effective in preventing rollover?Transporting Cargo Safely
  29. 229.You are driving a commercial vehicle and notice that the oil pressure gauge is showing a reading significantly lower than normal, but not yet at zero. What should be your immediate action?Driving Safely
  30. 230.A commercial driver is conducting a pre-trip inspection of their vehicle and notices a small oil leak from the differential. What is the most appropriate action to take?Driving Safely
  31. 231.A driver notices that the air pressure gauge shows a rapid drop in pressure when the service brakes are applied repeatedly. The low air warning light and buzzer activate almost immediately after a few brake applications. What does this most likely indicate?Air Brakes (if applicable)
  32. 232.What is the primary reason for a commercial driver to perform a 'one-two-three' count when starting the vehicle after a stop at a railroad crossing?Driving Safely
  33. 233.A commercial vehicle driver is performing a pre-trip inspection. They notice that the air pressure gauge builds from 85 psi to 100 psi in 30 seconds with the engine at operating RPM. What does this indicate about the air compressor's performance?Air Brakes (if applicable)
  34. 234.A commercial driver is transporting a load of heavy, rigid cargo that is 12 feet long and weighs 15,000 pounds. The cargo is not blocked or braced against the front of the trailer. What is the minimum number of tiedowns required to secure this load?Transporting Cargo Safely
  35. 235.A commercial driver is preparing for a long trip and notices a small amount of oil leaking from around the wheel hub of a drive axle. What is the most appropriate action?Driving Safely
  36. 236.During a pre-trip inspection, a driver notices that the brake pedal on their air brake equipped vehicle has no 'free play' or 'dead travel' when initially pressed. What could this indicate?Air Brakes (if applicable)
  37. 237.A commercial driver notices that their vehicle's dashboard air gauge shows a continuous, gradual drop in air pressure while the engine is running and the brakes are not applied. What is the most likely cause of this issue?Driving Safely