Q What is the purpose of having draft-gear slack in the era of diesel locomotives? We all know the steam engines needed slack to start the train, and slack is used to “cushion” coupling, but I’ve always wondered why the modern freight cars don’t “lock” the draft gear when the brakeline is charged up eliminating all slack motion. Wouldn’t train handling be easier without any slack at all? Wouldn’t there be less damage too?
— John Privara, Davis, Calif.
— John Privara, Davis, Calif.
A The short answer is that slack is as useful in starting and handling long trains with diesel locomotives as it was in steam days. Our train-handling practices have changed, but they still are largely based on having and managing slack. On a practical level, having some cars with slack and others without could cause all sorts of mischief for train handling, and it would take years, and billions of dollars, to have converted the fleet of 1 million-plus North American freight cars.
— John Hankey, railroad historian
