Steam & Excursion > Steam Engine Breathing

Can anyone explain the idle breathing patterns of the 3985....First the typical "in and out" pattern we are used to hearing followed by a much more rapid "panting"....almost like hyperventilating....then back to normal breathing. Compare this to simple and compound engines. Ideas, Explainations? BTW, the Steam crew actually "used" the articulation on both sides to help get the lifters on. Swining the smokebox out gave them more room to work. As spock would say: "Fascinating"

---

Think your hearing the cycling of the compound air compressors on the front end of the locomotive.

I\'m guessing, that alot of it may deal with the amount of air needed in the locomotive with the air compressors on the front end. I can ask Lynn on Thursday and see if he knows, just may be how the compressors work. I\'ve been around at times when the compressors sound like crap, squeeking and stuff. Thats my guess on keeping pressure up for the air brakes and everything that uses air on the locomotive.

When a steam governor shuts off an air compressor, there is a bleed port which continues to allow a small amount of steam to go to the compressor. This keeps the appratus hot and forces out any water which condenses in the piping and steam cylinders of the air compressor. It\'s just a large enough flow of steam to move the compress pistons periodically, causing the panting sound.