If the brakes "creep on," what should the train operator suspect?

When the brakes "creep on," it indicates that there is an unintended application of the brake system, which can often be traced back to issues within the brake control mechanisms. The presence of a leaky trip cock in the brake system is a primary suspect because this component is responsible for venting brake pipe pressure to release brakes. If the trip cock is leaking, it may not adequately release pressure, leading to a situation where the brakes can engage unintentionally or partially, which aligns with the described symptoms of "creeping."

This understanding of how a leaky trip cock can result in unintended brake application is critical for train operators to ensure the safety and efficiency of train operations. Other components like a malfunctioning brake valve or issues with the equalizing piston can also cause braking problems, but they would typically manifest in different ways rather than the subtle creeping effect specifically associated with a leaky trip cock. The air compressor, while vital for maintaining air pressure and system functions, does not directly contribute to unintentional brake applications in the way that a trip cock does. Hence, identifying a leaky trip cock allows for targeted preventive measures in train maintenance and operations.