Union Pacific 4-12-2

[philskene]

Union Pacific three cylinder 9000-class 4-12-2.

This is one of a payware package of four locomotives released some time ago by "The Cowboy".

Three of the locomotives have conjugated valve gear for actuating the middle cylinder. As can be see in the video, this is fully functioning.

The fourth locomotive has an additional set of external Walschaerts valve gear on the right side for the centre cylinder.

Best viewed full screen and HD:

https://www.youtube.com/watch?v=wX05S005XK4

[mipman25]

I believe the whistle needs to be changed to a Star 5-chime and the chuff rate needs to be doubled, but it's great besides that.

[sniper297]

Also needs to be articulated, I thought the decapod was nuts but 12 driving wheels? Never heard of that one, was that a rigid frame?

[philskene]

mipman --

" ... the chuff rate needs to be doubled .. ."

That would be correct if it was a four cylinder locomotive. This had three.

Jim --

" ... was that a rigid frame?"

See here:

http://www.trainweb.org/rlhs/collect...s/UP_9000.html

" ... it is the largest steam locomotive built on a rigid frame ... ."

I would suspect it had plenty of lateral play in the first and last axles. From the photographs looks like it has at least two knuckle joints in the connecting rods to allow for this.

[mipman25]

mipman --

" ... the chuff rate needs to be doubled .. ."

That would be correct if it was a four cylinder locomotive. This had three.

3-cylinder locomotives have six chuffs per revolution, just as how a two-cylinder has four per revolution.

[rdamurphy]

sniper, they were known as the Union Pacific type. Used on Sherman Pass and across Wyoming.

http://www.steamlocomotive.com/4-12-2/

IIRC, there's a very nice freeware version of it, also.

Robert

[portobellojct]

3-cylinder locomotives have six chuffs per revolution, just as how a two-cylinder has four per revolution.

go here for a sound recording of the 6 beat exhaust:

http://www.utahrails.net/up/up-4-12-2-sounds.php

a lot of british locos were multi-cylnder. the GWR / LMS 4-cylinder locos were the most succesful. Gresley's conjugated valve gear was an operational nightmare. It produced wildly erratic power outputs from the cylinders, as you can hear in this recording.