Illinois CDL Practice Exam

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Prepare for the Illinois CDL Exam. Utilize our comprehensive quiz featuring flashcards and multiple choice questions. Enhance your understanding and readiness for the exam with detailed explanations. Ace your CDL test and start your career in commercial driving!

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How would you verify that spring brakes come on automatically in an air brake system?

Monitor the brake pedal pressure
Activate the Modulating Control Valve
Reduce tank pressure while the electrical system is on
Turn off the engine to test the springs

The correct answer is: Reduce tank pressure while the electrical system is on

To verify that spring brakes come on automatically in an air brake system, you would reduce tank pressure while the electrical system is on. This action simulates a loss of air pressure in the system, causing the spring brakes to engage as a safety measure. By reducing the tank pressure with the electrical system still on, you can ensure that the spring brakes are functioning as intended. Monitoring the brake pedal pressure (Option A) will not necessarily verify the automatic engagement of the spring brakes. Activating the Modulating Control Valve (Option B) is not a standard procedure for checking the spring brake system. Turning off the engine to test the springs (Option D) does not specifically check the automatic function of the spring brakes. Therefore, the correct method to verify that spring brakes come on automatically in an air brake system is to reduce tank pressure while the electrical system is on.