I am not very familiar with steam loco equipment and sound files. (I was only five years old when steam was replaced by diesel on our local mainline.)
I am programming some sounds on one of my good steam decoders, and happened to increase the sound of a steam letoff, kind of alternating, as the loco first started to pull away. This is a steam let off that continues in addition to the chuffs that are increasing. I imagine this steam let off then ceases as the loco reaches higher speeds....at least it seemed to in my model. Then i had reason to reset all the sounds on the decoder and have forgotten which sound file I had increased the volume or frequency of to get that steam effect. I would be grateful for any ideas.
What decoder brand is it?
It sounds like the sound you are describing is the cylinder drains, explained here:
https://en.wikipedia.org/wiki/Hydrolock#Steam_engines
I agree with Andrew,
Cylinder cocks were opened to drain off condensed steam, i.e. water, so that the risk of blowing off the cylinder head or damaging the piston was reduced.
Conditions and locomotive designs varied but, generally, if the engine was going to sit longer than, say, ten or fifteen minutes, the cylinder cocks would be opened to allow the accumulated water to be forced out of the bottoms of the cylinders, both fore and aft. The engineer would close them, at his or her discretion but usually they only needed to drain for a minute or less after the engine was under way.
Have Fun, Ed
Yes, that would be the steam cocks on the cylinders, water doesn't compress, so any condensed water needs to be released. In extreme cases it will blow the head right off the cylinder.
Most steam sound decoders have this sound in there. Either triggered via a function or automatic when starting off, it's very different from the normal chuff since much of the steam escapes out the open valves instead of going up the stack, plus in a typical trackside position you would be much closer to the source than the sounds coming from the stack.
And when visiting steam operated tourist railroads, one quickly learns not to stand near the front of the loco when they are about to get underway.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Excellent. Thanks for the tips. I will modify that setting until I get back to the sound I want, which is similar to the one on my video of a local steam loco.
The cylinder cocks are not just opened to expel condensate; they are kept open while the cylinders themselves heat up to the point the 'steam surfaces' reach operating temperature (during which time further condensation will be occurring).
While we are on this general subject: are there any sound files or codes for operation of Okadee blowoff cocks (i.e. compression relief) which would actuate if the pressure in the steam space went unusually high?