Under what condition will the brakes on these cars not apply in an emergency?

The brakes on the train cars will not apply in an emergency condition when the reverse handle is forward and the brake valve is in full service. This means that if the train is actively transitioning into reverse operation while simultaneously applying the brakes in full service, the system is designed to prioritize control related to the forward motion, thus not engaging the emergency brakes under these circumstances.

Maintaining safety and control is paramount for train operations, and the system is engineered to prevent unintended brake applications that could occur during a shift in operational mode. This helps prevent erratic movements or disruptions that could endanger the train's operation or safety. In this specific scenario, the system recognizes that the intention is not to come to a sudden stop but rather to manage the train's operations in a specific direction.

In contrast, the application of brakes under other conditions, such as when the master controller handle is released, would typically allow for a safety mechanism, and the emergency brake will initiate if necessary when activated. Additionally, speed limits also govern appropriate braking responses, but the combination of having the reverse handle forward with the brake valve in full service represents a unique operational situation preventing the brakes from applying as an emergency safety measure.