Coupler height on adjacent coupled cars should not vary more than how many inches?

The acceptable variation in coupler height on adjacent coupled cars is up to 3 inches. This standard is critical for maintaining the proper alignment and function of the couplers. Couplers are the mechanical devices that connect train cars, enabling them to work effectively as a unified system. If the height of the couplers varies excessively, it can lead to operational issues, such as derailments or increased wear and tear on the couplers and rail cars.

The reason the specified maximum variation is limited to 3 inches is to ensure safe and efficient train operations. If the couplers are too far apart or misaligned, it can cause the train to operate uneasily, creating potential hazards when the train is in motion. Ensuring that any height difference falls within this limit allows for smoother coupling and uncoupling processes and helps maintain the stability of the train while traveling, ultimately enhancing safety for both the train and its cargo.