How is the automatic brake valve handled during the leakage test?

In the context of the leakage test, the automatic brake valve must be cut out to ensure an accurate assessment of the system's integrity. Cutting out the automatic brake valve allows the tester to isolate the brake system from the valve's potential influences, thus enabling a more precise measurement of air leakage in the system components that are being tested. This isolation is critical for identifying leaks without interference from the valve itself or any pressure changes that might be caused by the valve's operation.

In this situation, cutting out the valve also helps prevent unintentional activation of the brake system during the test, which could lead to inaccurate results or safety hazards. Therefore, this procedural step is essential in maintaining the reliability of the leakage test and ensuring that the brake system can be verified properly before being returned to service.