CDL Vehicle Combination Practice Test

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Prepare for the CDL Vehicle Combination Test. Access multiple choice questions, detailed answers, and hints to guide your study. Ace the exam with confidence!

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What should you do before you proceed with a trailer coupling?

Adjust the load balance
Verify that the air system is fully charged
Ensure that the trailer is properly supported
Clean the connection points

The correct answer is: Verify that the air system is fully charged

Before proceeding with a trailer coupling, verifying that the air system is fully charged is crucial. In combination vehicles, the air braking system is essential for safe operation. A fully charged air system ensures that the brakes can function correctly when needed, which is vital for safety during driving. If the air system is not fully charged, the brakes may not engage properly or could fail altogether, leading to potential accidents. While adjusting the load balance, ensuring proper trailer support, and cleaning connection points are important aspects of safe trailer operation, they are secondary to the operational readiness of the air brake system. If the air system is compromised, no amount of preparation in these other areas can account for the dangers posed by inadequate braking capability. Therefore, the priority must always be to ensure that the air system has sufficient pressure for reliable brake performance before coupling the trailer.