Subject:
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Re: What is the largest lego steam engine ever built?
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Newsgroups:
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lugnet.trains
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Date:
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Fri, 17 Dec 1999 23:22:34 GMT
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Viewed:
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873 times
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In lugnet.trains, Steven Barile writes:
> Dan
> Now that is unbelieveable! I must have missed that original posting!
> http://www.visi.com/~blackened/gallery/loco/loco.html
>
> Larry or anyone. What does the real Big Boy look like (from the top) when
> going around a tight curve? Is there a pic anywhere? Where are the pivot
> points?
> SteveB
Remember, real curves are not very tight. You get at most 2 feet or so of
variance from tangent unless we're talking extremely light branches or logging
roads...
I'm not sure if there are pics of it from the top on a tight curve...
MOST 2 driver set articulateds (2DSAs) have a rigid connection to the rear
set, that is, the frame of the locomotive holds the back part of the boiler
and firebox rigidly connected. The trailing truck, if there is one, pivots
from the end of the frame. It bears some weight of the fire box and cab on
sliding bearing surfaces, but as little as one can get away with (unpowered
trucks did not contribute to tractive effort... hence the use of powered
booster trailing and tender trucks, but that would be another post)
MOST 2DSAs have an articulation point between the rear set and front set of
drivers. Thus, the front set swing from side to side. The pilot truck, if any,
doesn't bear much load and is there mostly to make sure the front drivers
track true.
MOST 2DSAs have a rigid boiler all the way up to the smokebox. Since the
boiler overhangs the articulated front set of drivers, it either cantilevers
out (if it's a big smokebox, that weights a lot less than the water bearing
part of the boiler) or rests on saddles that sit on the front subframe.
Typically these are at or near the front cylinders, which are big castings and
have to tie to the frame anyway.
I don't exactly know what the reading triplex and the virginian triplex did.
I said most above because I know of at least one articulated that had an
articulated boiler. It was actually only the smokebox, but there are accordion
pleats in the jacket casing and the smokebox is rigidly attached to the front
driver frame. The entire engine bends! Not very successful for fairly obvious
reasons. (it leaked smoke and had a very poor draw, for one thing....)
Basically, as conservative as RRs are individually, in the aggregate there was
a lot of experimentation! If you can think of it, some fool tried it. They
have had 175 years to experiment, after all.
++Lar
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Message has 2 Replies:
 | | Re: What is the largest lego steam engine ever built?
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| (...) Lets just say Mallet, since that is what it is...not a Fairlie or a Beyer-Garratt (although, a true mallet is compound...like a Y6B) (...) You should only -see- what was tried... Hmm...now that gives me a idea...a large prototypical engine (...) (25 years ago, 18-Dec-99, to lugnet.trains)
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Message is in Reply To:
| | Re: What is the largest lego steam engine ever built?
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| Dan Now that is unbelieveable! I must have missed that original posting! (URL) or anyone. What does the real Big Boy look like (from the top) when going around a tight curve? Is there a pic anywhere? Where are the pivot points? SteveB (...) axels (...) (25 years ago, 17-Dec-99, to lugnet.trains)
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