Which of the following pressures are equalized during an emergency brake application on a freight car?

During an emergency brake application on a freight car, it is crucial to understand the role of the various reservoirs and cylinders involved in the braking system. When the emergency brake is activated, the pressures in the auxiliary reservoir, brake cylinder, and emergency reservoir are equalized to ensure effective and immediate braking action.

Equalizing the pressure between these components is essential because it allows for the rapid and consistent application of the brakes across all freight cars in a train. The brake cylinder generates the force needed to slow down or stop the car, while the auxiliary reservoir stores compressed air that is used to maintain brake pressure. The emergency reservoir acts similarly but is specifically designed to provide additional capacity for emergency situations.

By equalizing these pressures, the braking system can respond swiftly to both the driver's input and any emergency situations, maximizing safety. This coordinated action ensures that all freight cars apply brakes simultaneously, preventing potential derailments or loss of control of the train.

Understanding this interplay among the auxiliary reservoir, brake cylinder, and emergency reservoir highlights the importance of each component in maintaining effective braking performance during emergencies. Therefore, all three pressures are equalized during an emergency brake application, justifying the correct answer.