In the event of a brake application from the leading cab, which cars will have their brakes applied if the double cut-out cock on the fifth car is closed?

The correct response reflects a fundamental understanding of how train braking systems operate, particularly in relation to the double cut-out cock. When the leading cab makes a brake application, the brakes are typically designed to engage throughout the train. However, the presence of a closed double cut-out cock on the fifth car prevents the brakes from being applied in that specific car.

In this scenario, the double cut-out cock functions as a manual or automatic isolation device that can segment the braking system, thereby preventing that section of the train from receiving the brake signal. Since the cock is closed on the fifth car, its brakes will not be activated, but the rest of the train will respond to the brake application from the leading cab.

Consequently, all of the other cars, which are connected and not isolated by the cut-out cock, will have their brakes applied, resulting in all cars but the fifth car experiencing the brake application. This is crucial for maintaining safety and operational efficiency, as it allows for controlled braking throughout the train, except for the isolated section.