Dennis,

Thanks for posting those photos of the Central Pacific engines. What I want to see of the tender truck design for Leviathan and Jupiter are the details of the center bearing, which are typically not visible in photographs. And then I want to learn how the builders of the replicas discovered the historical accuracy of the hidden details. I suspect that the builders of the replicas may not have found historical references to these hidden truck details, and therefore developed their own design that may or may not have been historically accurate in both detail and principle. I am interested in learning the correct historical details.

When I said in an earlier post that the replica builders probably used best practice to resolve the design in areas they could not confirm in photos, I meant best practices of today, not the practices of the historical era. The latter would have probably been as difficult to confirm as the actual details. Determining best practices for the minutia of the historical period would have required dogged research, judgment calls, and best guesses in sifting though all the available examples of historical details. So, instead of going that route, I suspect they would have simply used best practices of today.

I see further evidence of this approach in their expressed enthusiasm for improving the historical design by substituting their own improvements over known historical precedent. Depending on how much of that went into these new locomotives, I get a little uneasy calling them replicas. For instance, the builders of the replicas decided to cast the cylinder block in one piece instead of the three-piece historical design because the original design had a problem with the bolts holding the three pieces together loosening up in operation. They did an excellent job on so much of the replicas, but I am disappointed that they would suddenly jump the track of their historian role and become product improvement engineers. The original locomotives would have lived a far more rough and tumble work life than the replicas ever will, so if the bolts did loosen up on the originals, I doubt that would be a problem on the replicas.

For the tender trucks with the big side springs, I see some fundamentally sticky problems that the original design would have had to deal with in the hidden areas. With a predilection toward improving the original locomotive design, I am curious about how these tender trucks are executed on the replicas, and whether the engineering drawings for the replicas can be used as reference for historical practice.