Answer :
Final answer:
In a duel air braking system, the governor must cut IN, or start working again to increase pressure, when the system pressure falls below 85 psi. The governor essentially controls the air pressure within a specified range which is crucial for the proper functioning of the brakes.
Explanation:
In a duel air braking system, the governor plays an essential role in maintaining the correct pressure in the system. For safety and proper function, the governor should cut IN when system pressure drops below a designated value. According to regulatory standards, this value is 85 psi. So, the answer to your question is C. 85 psi. It's important to note that the cut OUT (when the system pressure stops increasing) usually occurs around 120-135 psi.
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