CDL (Commercial Driver's License) Practice Test (Air Brakes #1)

Welcome future truck drivers! The following is the CDL Air Brakes Practice Test #1. If you're going to drive a commercial vehicle with air brakes, you'll need an Air Brakes Endorsement on your CDL (Commercial Driver's License). Simply click in your answer (A,B,C, or D) to each CDL practice test question. When you're done, check your score and the results. You can reset the test and retake it as many times as you want.

CDL Air Brakes Practice Test #1 Start Now 1. Brake drums... A Are bolted to the wheels B Are located at each end of the vehicle's axles C Hold the brake shoes and linings D All of the above 2. When the low pressure warning is activated, you should... A Wait for the air brakes to come on automatically B Bring the vehicle to a safe stop while you still control the brakes C Monitor your air pressure gauge and maintain highway speeds D Pump the brake pedal hard to stop 3. When the safety valve releases air it means that... A The pressure has exceeded 150 psi B Too much air is in the air compressor C Something is wrong, and you should have it checked by a mechanic D All of the above 4. In a single vehicle with a fully charged air system, air pressure loss (after an initial drop) should be less than... A 2 psi per minute B 3 psi per minute C 4 psi per minute D none of the above 5. The service brake system... A is an official vehicle inspection B applies and releases the brakes by using the brake pedal under normal driving C are the valves that keeps the air tank pressure serviced D is only on vehicles with hydraulic brakes 6. Your vehicle's single brake system needs adjustment if... A pressure builds from 50 to 75 psi within three minutes B pressure builds from 85 to 100 psi within 45 seconds C the compressor cuts out between 70 to 90 psi D the governor stops between 75 to 90 psi 7. Some air brake systems have an alcohol evaporator which helps... A Reduce the risk of ice in the air brake valves during cold weather B Remove oil from the air lines C Reduce the risk of water in the air brake valves in warm weather D Remove fuel from the air lines 8. Air tanks should be drained... A Once a week B Once a day C Every four hours D Every two or three days 9. The safety valve in the air compressor tank is set to open at... A 150 psi B 200 psi C 100 psi D 175 psi 10. Compressed air is stored... A In the hoses B In the engine compartment C In the fuel tank D In the storage tank 11. When you apply pressure to the brake pedal, you are... A Pushing against a spring and against air pressure to the brakes B Releasing air pressure to the brakes C Reducing air in the tanks D Activating the safety valve 12. The air compressor is connected to the engine through... A Gears B Hoses C V Belt D Both A and B 13. Which type of brake is the most common in commercial vehicles? A Wedge brakes B Disk brakes C S Cam brakes D Drum brakes 14. An air pressure gauge... A Shows how much pressure you are applying to the brakes B Is connected to the generator C Releases air when you accelerate D Prevents brake failure 15. All vehicles with air brakes are required to have a low pressure warning signal. This could be... A A red light B A wig wag mechanical arm C A buzzer D Any one of the above 16. The Air Compressor Governor controls... A When the brakes should be applied B When the air compressor pumps air into the storage tanks C When the warning light is activated D When the air is released from the tank 17. A duel air brake system... A Has two air brake systems and one set of controls B Takes less time to build air pressure C Has one set of air tanks and hoses D Must have two warning alarms 18. An emergency brake... A Is required on commercial vehicles B Must be held on by mechanical force C Could be activated by the loss of air pressure D All of the above 19. To check the slack adjusters on S Cam brakes, you should... A Leave the parking brakes on and pull on the slack adjuster B Wear gloves and pull hard on each slack adjuster C Make sure the slack adjusters move more than one inch each way D Drain the air from the system and pull on the slack adjusters 20. To test the low pressure warning signal, you should do all BUT the following... A Shut the engine off B Turn the electrical power on C Ask a friend to listen for the signal D Step on and off the brake pedal to reduce air pressure 21. With dual air systems, the air pressure should build... A From 85 to 100 psi in 45 seconds B From 70 to 100 psi in 60 seconds C From 85 to 150 psi in 45 seconds D From 70 to 150 psi in 60 seconds 22. A fully charged air system typically has ____ psi. A 100 B 125 C 150 D 175 23. To test the air leakage rate you should... A Leave the engine running and release the service brake B Turn off the engine and release the service brake C Charge the air system and leave the engine running D Depress the brake pedal and monitor the air pressure gauge 24. A combination vehicle air brake system should not lose air faster than... A 2 psi per minute B 3 psi per 30 seconds C 3 psi per minute D 4 psi per minute 25. To check the air compressor governor "cut in" and "cut out" pressures... A Run the engine at a fast idle B Step on and off the brake to reduce tank pressure C Monitor the air pressure gauge D All of the above 26. To test your service brakes you should... A Stop the vehicle and put the parking brake on B Release the parking brake, move forward slowly and depress brakes C Put parking brake on and release air pressure D Depress brakes when traveling at highway speeds 27. Stab braking occurs when you... A Press on the brake pedal as hard as you can B Release the brakes when the wheels lock up C Apply the brakes when the wheels start rolling D All of the above 28. Air brakes take longer to stop than hydraulic brakes because... A The reaction time is longer for the driver B It takes longer for the air to flow through the lines C The linings get hotter more quickly D None of the above 29. The proper way to go down long grades is to... A Use a low gear and push hard on the brakes B Let up on the brakes from time to time to cool them C Use a low gear and apply light pressure on the brakes D Brake on and off down the hill 30. You should avoid using the parking brake... A on steep hills B if the air pressure is low C when the brakes are hot D any time you park 31. Air tanks should be drained... A at the end of each day or shift B to keep sludge from clogging brake system valves C manually when automatic devices fail D all of the above 32. Fanning air brakes... A cools them off B increases the air pressure C increases the braking power D decreases the air pressure 33. If your air compressor stops working... A you will lose your brakes immediately B the brakes will immediately lock up C you'll still have air pressure left in the air tanks D your brakes won't be affected 34. The governor allows the air to start pumping again when it reaches the cut in level, or around... A 200 psi B 100 psi C 150 psi D 125 psi 35. You should not use the parking brakes... A on a steep hill B if the air pressure is low C when the brakes are hot D in hot weather 36. The brake drums or discs... A must have linings that fit loosely on the brake shoes B must not have any cracks C must not have cracks longer than half the width of the friction area D should be kept well-greased 37. Slack adjusters... A never need to be adjusted B should only be adjusted by a qualified mechanic C can be adjusted manually or automatically D should travel at least two inches from where the push rod is attached 38. To determine if slack adjusters need adjustment... A apply the service brakes and release the parking brakes B apply both the service and parking brakes C pull out the automatic slack adjustment control knob D release both the service and parking brakes 39. An air tank is equipped with a drain valve to remove... A Air and water B Oil and air C Water and oil D Dirt and oil 40. The governor stops pumping air when it reaches the "cut out" level, or around... A 125 psi B 200 psi C 225 psi D 175 psi Test Score = Correct answers: Get My CDL! The New Trucker Career Center CDL Practice Tests Access Page Trucker Country Home Page Choose from these additional practice tests... CDL General Knowledge Practice Test #1 CDL General Knowledge Practice Test #2 CDL Hazardous Materials Practice Test #1 CDL Hazardous Materials Practice Test #2 CDL Air Brakes Practice Test #2 CDL Doubles and Triples Practice Test #1 CDL Doubles and Triples Practice Test #2 CDL Combination Vehicles Practice Test #1 CDL Combination Vehicles Practice Test #2 CDL Tank Vehicles Practice Test #1 CDL Tank Vehicles Practice Test #2 Jim Purcell, President of Trucker Country, has put together the ultimate series of trucking guides for anyone interested in a career as a professional trucker. Whether you're just curious about trucking or you're ready to become a successful truck driver, you'll find all the real-world information you need in this amazing series of guides. Learn, step-by-step: the truth about the world of trucking, how to become a trucker, and even how to succeed at the trucking job and life.

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