What is the brake cylinder pressure on a cab car when the brakes are applied?

In the context of a cab car's air braking system, the brake cylinder pressure is vital for ensuring safe and effective braking. Typically, a cab car, which is designed to lead trains, utilizes air brakes that operate under standard pressure settings. When the brakes are applied effectively, the brake cylinder pressure is set to a standard operational level that allows for sufficient deceleration and stopping power.

The correct answer, indicating a brake cylinder pressure of 30 PSI, aligns with the standard operating procedures for many cab cars in the LIRR system. This pressure is designed to provide an adequate braking force while ensuring that the system does not experience excessive wear or failure. Maintaining the proper brake cylinder pressure is crucial for the safety of the train and its passengers, allowing for responsive braking without overshooting or experiencing brake fade.

Conversely, the other pressure options like 45 PSI, 55 PSI, and 70 PSI are typically not standard for a cab car under normal braking operations. They may represent pressures used in different contexts or equipment, emphasizing the importance of understanding the specific operating parameters for each type of railcar. Understanding these values helps ensure that the air brake systems are used correctly and effectively on the LIRR.