Steam Loco Question

Trains Magazine General Discussion
1

Below is a detail of the right side of a Union RR 0-10-2. I’ve got a question about the coils above the air reservoir on steam locomotives. Looking at the pictures that I have, the coils seem to run between the air pump and the air reservoir. Does this have something to do with moisture in the air? What happens to the water? This one seems to have 4 circuits, however, other locomotives have more, some less, some none. Why? Is it because some locomotives drew on the air pressure more than others? Were the coils always above the reservoir?

Thanks!

2

When air is compressed it heats up. These coils of pipes act like radiators (air doesn’t hold much heat so proper rads ain’t needed). In this case the water condenses and ends up in the reservior, there’ll be a drain valve somewhere at the lowest level that water seeks.

Why some engines had them and why others didn’t depends on a number of things. Air consumption, temperatures that the engine was used in, general humidity and railroad cheapness to name a few.