Who can tell me what the valves or vents on the bottom of the cylinder’s are for? Generally these are not found on model locos, unless added or the loco is done in brass. Some of my video tapes show these valves venting steam, and this appears especially at low speeds. I have both Westcott’s Steam Locomotive Cyclopedia and Kalmbach’s Guide to North American Steam Locomotives. Niether of these books descibe these valves. Also, what is a good book describing the actual operation of a steam loco, from either the Engineer and/or Fireman’s point of view?
I’m pretty sure that those valves you’re reffering to are drain valves for the steam cylinders. As the steam cools it turns to water which can accumulate in the cylinder. Water doesn’t compress so in theory if enough water is in the cylinder, the front of the cylinder could blow off as the piston compresses it.
Ed
If you ever see an excursion steam locomotive start out you’ll see these valves in action. For general info on steam locomotives I recommend the Linn Westcott book from Kalmbach. It is pricey but I see them on sale at swap meets from time to time
Dave Nelson
When a steam engine starts the cyliners are cold and cause condensation to form. Water will not compress and the clearance of the piston head to the cylinder head has caused some engines to blow the cylinder head off the engine from the compression. These valves offer a way to heat the cylinder and vent the water. There is an additional valve on some engines or those can be used to equalize steam flow to both sides of the piston. If an engine has a slightly leaking throttle valve it can walk away at a pace no one can see from going through the steam cycle. By opening a connecting pipe to both side of the piston the pressure builds up equally and the steam engine stays put. On the PRR these are the star shaped items on the steam delivery pipe above the cylinder chest and are called snifter valves.
you want to learn all there is about firing a steam loco, or operating it? if you live near a tourist line that runs steam excursion trains, you can learn all about firing and operating a steam locomotive by becoming a volunteer part-time helper. you get around trainmen, ask the right questions, and then wonder how you will ever get them to quit talking. you can learn all you want to about the care and keeping of steam locomotives.
And the fireman will show you how to read the water glass, and how to blow it down… and the engineer will show how the water level is judged by using the tri-cocks…