What is the generally acceptable change in psi needed to confirm either application or release of the brakes at the rear of the train?

The generally acceptable change in psi needed to confirm either application or release of the brakes at the rear of the train is 5 psi. This standard is established to ensure that there is a reliable indication of brake actions across the entire length of the train, as any sudden changes in brake pressure can impact safety and efficiency.

A change of 5 psi is sufficient to demonstrate that the desired action (application or release of brakes) has occurred effectively. If the psi change were too small, it might not be a reliable indicator, whereas a larger change might indicate a potential fault or issue within the braking system. Therefore, a 5 psi change strikes a balance, allowing for effective monitoring of the brakes while minimizing the risk of misinterpretation or failure to detect proper brake functionality.