What is the minimum acceptable brake pipe increase at the rear of the train after releasing the brakes during the air test?

The minimum acceptable brake pipe increase at the rear of the train after releasing the brakes during the air test is established to ensure that the braking system is functioning properly. A 5 psi increase indicates that the brake system is responsive and that any potential leaks or inefficiencies in the brake pipe are within acceptable limits.

When the brakes are released, the brake pipe should ideally build pressure uniformly along the length of the train. An increase of 5 psi shows that the system is receiving sufficient air pressure to reset the brake cylinders effectively. This is crucial for maintaining safe train operations, as inadequate pressure build-up could point to issues like leaks or malfunctioning components that might compromise braking efficiency.

Higher thresholds, while potentially acceptable in specific or rare scenarios, would not be the minimum standard for safe operation, and lower thresholds would signal an inadequate response from the braking system. The choice of 5 psi is strategically positioned to balance safety, operational integrity, and mechanical efficiency.