Answer :
Final answer:
In engineering, charging the trailer air brake system involves pressurizing it with air to ensure proper functioning. Pulling out the trailer air supply control allows air to flow into the system. After charging, it is important to check that the trailer rolls freely.
Explanation:
In the context of a trailer air brake system, charging the system refers to pressurizing it with air. This is done to ensure that all components are in proper working order and ready for use. To charge the system, the trailer air supply control (also known as the tractor protection valve) is pulled out, allowing air to flow into the system. After charging, it is important to check that the trailer rolls freely, meaning that it can move without any resistance or obstruction.
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