While stringing a lanyard to the bell on a new Bachmann Spectrum 2-10-0 Russian Decapod, I found a small valve on the right hand side of the steam dome, leading me to examine my three older Dec's, to find that they also had the same feature. I was surprised that I had missed that valve while working on the earlier loco's.
The valve appears to have been lanyard activated, presumably by the engineer; perhaps to relieve steam pressure? It's not a safety valve, since the safety valve, and the whistle, are located on a turret just in front of the cab.
Isambard
Grizzly Northern history, Tales from the Grizzly and news on line at isambard5935.blogspot.com
"Heeeeear that looooooonesome whiiiiiiiiiiiiiiiiiiistle blooooowww......"
If you're referring to the arm-controlled valve on the engineer's side, it's the most important valve on the locomotive! The Russian Decapod had an outside-controlled in-dome throttle valve. That's not a lanyard, it's a steel push-pull rod.
Most contemporary US design locomotives had the throttle valve control arm and linkage inside the boiler. OTOH, all of the more modern Japanese steamers had dome-mounted throttle valves with outside linkages that incorporated an expansion-compensating bellcrank in the rodding.
Chuck (modeling Central Japan in September, 1964)
selector wrote: "Heeeeear that looooooonesome whiiiiiiiiiiiiiiiiiiistle blooooowww......"
Whistling in the dark? Nope!
Looking more closely at the steam dome I found that the "valve" is not a valve at all, but a flat square plate mounted on the dome, holding a protruding shaft. Therefore it looks like the throttle valve is located in the steam dome. Hmmm, looks as if I have I need a control rod from the engineer's position, rather than a lanyard.
tomikawaTT wrote: If you're referring to the arm-controlled valve on the engineer's side, it's the most important valve on the locomotive! The Russian Decapod had an outside-controlled in-dome throttle valve. That's not a lanyard, it's a steel push-pull rod.Most contemporary US design locomotives had the throttle valve control arm and linkage inside the boiler. OTOH, all of the more modern Japanese steamers had dome-mounted throttle valves with outside linkages that incorporated an expansion-compensating bellcrank in the rodding.Chuck (modeling Central Japan in September, 1964)
Thanks Chuck. I didn't check for the latest incoming before I typed and posted my last message above.
NB: I always find your postings interesting.
Cheers!
From several on-line photos of prototype Russian Decapods it would appear that the throttle lever on the steam dome was connected to the engineer's position in the cab by a one-piece rod about 10 feet long, perhaps supported in the middle by a hangar. That detail is not clear. Can anyone confirm this
In the RMC December 2002 issue the feature article by Rob Davis shows the Reading prototype with two short rods connected at the mid point through a bell crank. Was this Reading's preferred solution for mechanical reasons
The Reading modification to the Russian specification was meant to compensate for the expansion of the boiler. Since the linkage was exposed to outside air at ambient temperature, it was unlikely to expand at the same rate as a boiler taken from banked fire (or dead cold) to full operating temperature at 180psi. Depending on exactly how the linkage was connected to the throttle lever, this could either put tension stress on the link rod or cause the throttle to creep open (not my idea of a fun situation!)
The standardized Japanese designs all incorporated expansion compensating bellcranks in their throttle linkages. So did more modern American steamers with front-end throttles.