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

The correct answer regarding the acceptable variation in coupler height between adjacent coupled cars is three inches. This standard is critical for ensuring safe and efficient train operations. If the coupler heights vary significantly, it can lead to mechanical issues such as binding during operation or increased wear on the couplers and other connected components. This level of tolerance helps maintain proper alignment and facilitates smooth coupling and decoupling of rail cars.

A variance greater than three inches could lead to dangerous conditions during transit or while loading and unloading railcars, making it essential for rail mechanics and service workers to ensure that coupler heights are within this limit. This standard is typically established in compliance with industry regulations and best practices to ensure the safety and reliability of train operations.

The options representing lower or higher thresholds do not align with established safety standards in rail operations, emphasizing the importance of maintaining the three-inch limit for effective coupling performance.