When must a Class I Air Brake Test be conducted?

A Class I Air Brake Test is essential to ensure that the air braking system of a train functions correctly and safely before it begins its journey. This test must be conducted when a train is originally assembled to verify that all components of the air brake system are operational and that the system is properly charged. This includes checking the integrity of the connections, the functionality of the brake apparatus, and ensuring that there are no leaks in the system.

Conducting this test at the point of assembly is crucial for safety, as it minimizes the risk of brake failure during transit and ensures compliance with regulations. By verifying the system's readiness prior to dispatch, the crew can be more confident in the train's performance during operation.

While other events such as crew changes and repairs may prompt additional checks, they do not replace the necessity of performing the Class I test when a train is initially put together.