Answer :
Final answer:
The tractor-protection valve cuts the trailer supply first when there is a system air pressure loss on a trailer, to prevent the complete loss of air needed for the tractor's braking system.
Explanation:
When a system air pressure loss occurs on a trailer, leading to a gradual bleed down of pressure, the event that occurs first is typically the activation of the tractor-protection valve, which acts to protect the tractor's air supply. Specifically, this would be option b, the tractor-protection valve cuts the trailer supply, to prevent complete loss of air pressure for the tractor, which needs it for its own braking system.
As the system air pressure continues to drop, additional steps will follow, such as the application of the spring brakes on the trailer when pressure drops to a certain threshold, often around 20 to 45 psi, not immediately at 60 psi as option c suggests. Prior to this, the trailer's service brakes will not automatically apply; this action usually requires a driver's input unless there's a specific emergency feature in the brake system designed to do so.
Option D is correct. Safeguards the air brake system in the event that the air suspension system leaks or fails.
A replaceable filter on Premium Valve prevents pollutants and other debris from getting into other air system components. The front or rear brakes won't function properly if one air system has very low pressure. As a result, stopping will take longer for you. Stop the car safely, then get the air brakes system fixed. safeguards the air brake system in the event that the air suspension system leaks or fails. A replaceable filter on Premium Valve prevents pollutants and other debris from getting into other air system components.
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