Did these two 4-6-6-4 Challengers share similar parts? The Rio Grande L-105 and Western Maryland M2s

[Engi1487]

• Hello everyone. So everyone is familier with the Union Pacific Challengers, but I learned of other classes and types American railroads used, such as the Rio Grande L-105. They where known for their large hazard striped pilot mounted sandboxs. There was also the Western Maryland M2s, as they where only Challenger type used on the east coast where the WM's trackage was.
• Both where built by Baldwin Locomotive works, so did they share a similar chassis or parts?
• I product suggested these two to a well known manufacturer of steam locomotives in HO scale a few days ago. They where in made in brass long ago, so it would be good to see new RTR versions of them done.
• The company I emailed are known for their models of the late style Union Pacific Challengers [same class/style that UP 3985 belongs too] with the centipede tender. Rio Grande & the Clinchfield RR owned the same style as well.
• I feel the market is a bit oversaturated with UP style Challengers. The market could use new variations of other 4-6-6-4s American railroads owned. The guy from the model railroad company I emailed replied back, thanking me. He said the L-105 was on the list but not in design yet.
• He wants to know if the WM Challenger shares common parts/same chassis with the L-105. At first glance they don't, but if so, they could probably do both! This would make it easier to design both and possibly announce around the same time.
  

[rcdrye]

Based on info from steamlocomotive.com the frames were very close in size, with most dimensions within an inch of each other, including wheelbase, cylinder size and driver diameter. I recommend the site as a good source for the kind of info you're looking for.

[Overmod]

rcdrye

Based on info from steamlocomotive.com the frames were very close in size, with most dimensions within an inch of each other, including wheelbase, cylinder size and driver diameter. I recommend the site as a good source for the kind of info you're looking for.

That is in fact the source I used in saying the designs were so dissimilar.

When discussing cast engine beds, wheel spacing is a critical measure, not 'well, it's just an inch'.  Same with the OD and porting of 23" vs. 22" cylinders, or detail of 70" vs 69" drivers (even if the wheel centers were the same design, and they could be because the stroke is the same).  

You could try the same argument comparing the C&NW E4b with the Milwaukee F7.  These are nearly coeval designs from Alco (1938) with very similar dimensions.  Railfans love to claim they are near-littermates.  But look at the detail design and there are all sorts of differences, and look at the reported performance and all hell breaks loose.

[rcdrye]

All of your comments are valid, but I was looking narrowly at the question originally posed, or at least hinted at - could models of both Challengers share common frames and running gear.

[Overmod]

rcdrye

...could models of both Challengers share common frames and running gear.

Yes and no.

The control dimensions for a functional model-locomotive chassis for a L-105 are, as noted, within 'eyeball range' at HO scale for a WM locomotive.  You'd need different castings for the smokebox end of the boiler, as the WM locomotive has more structure over the forward cylinders.  Use common driver centers and carry the diameter difference in tires (you'd accommodate the 'ride height' with bearing shims or similar method).

The problem is, for what it would cost to produce this thing, most interested people are going to want rivet-counter proportion and detail.  And everything about the L-105 frame is not right for the M-1; it's just close enough for those who don't want to know better.

An intermediate 'approach' would be to make the boiler and some of the attach pieces 'modular' so that either the tooling or pieces of molded production could be assembled for particular stages of a 'run'.  You could then assemble with different firebox sides, smokebox pieces, auxiliaries, etc. just as current runs of locomotives are customized to prototype.  You'll need very, very careful liaison with your production company and its subs/ICs to make sure the people doing assembly and packaging know what they're doing in minimum time with minimum rework.