If a train is stationed where the locomotive brakes won't hold when released, what should be done before opening the angle cock?

The correct choice involves making a 40 psi brake pipe reduction, which serves an important purpose in this scenario. When a train is stationed but the locomotive brakes will not hold when released, it indicates a potential risk of the train moving unintentionally. By making a 40 psi brake pipe reduction, you effectively create a safety measure that helps ensure that the brakes remain engaged on the entire train. This reduction in brake pipe pressure allows for the braking system to maintain a secure hold on the train, helping to prevent any potential rolling or movement when the angle cock is opened.

This action is vital for safely managing the air brake system and ensuring proper handling of the train, especially during maintenance or when preparing for moving the train. Taking this step minimizes the risk of accidents and maintains the integrity of the train's operations, particularly in situations where the locomotive brakes are in question.

Alternatives to this action, such as securing the cars with handbrakes or performing a thorough inspection of the brakes, while important in their respective contexts, may not provide an immediate solution to the problem of the locomotive brakes not holding. Similarly, sending a radio notification to the dispatcher might be necessary for communication, but it does not directly address the mechanical safety of the train at that moment