Neat discussion on how locomotives fit and work on different railroads -- just the kind I like.
There were many outside frame locomotives around when the EBT mikados were built. It could be the EBT people were just too tradition bound to try something different like outside frames. the question of clearances also probably played a big role as suggested in another post. In any event the big #16, 17 and 18 are very nicely proportioned engines and could pull their tonnage.
I cannot find the rigid wheelbase for the EBT mikes. Does anyone know what it is? A K-36 has a rigid wheelbase of 12' 3" according to the 1941 Locomotive Cyclopedia. An EBT mike undoubtably has a longer rigid wheelbase because it has an aggregate 16" more "wheel" than the D&RGW machine. More importantly, the allowable swing of the pony and trailer truck will limit an engine's curve radius too. I will bet the EBT engines have less allowable swing than the D&RGW machines which probably had extra swing built in for curves like 26 deg. Blind tires help, but they will drop off the inside rail if the fore and aft driver lateral is big enough and the rail is small enough. Some logging railroads put extra rails on the inside of sharp curves to keep the blind drivers from dropping through and chewing up the ties. It wouldn't take much of an engineering exercise to visit these locomotives and the curve issue and put it to bed for once and for all.
There are several formulas for calculating the required rail weight for a given drive wheel load (generally considered to be the worst case design criteria). However, both the EBT and D&RGW are special cases. Their rail may have been relatively light, but both railroads seem to have very tight tie spacing. In the case of the EBT they had exemplary track structure with good ballast and a lot of ties, thus increasing the carrying capacity of their rail. Broken rails in later years may have been due to a slackening in the roadway maintenance that allowed pumping track to break more of the aging, worn rail in the line. When I was in Chama last fall I commented one of the things that helps keep that railroad in line is the enormous number of ties on what seemed to me to be tight tie spacing. I hope this year's tie program can catch up on deferred tie replacements over the past few years.
While you guys are drooling over those big long wheelbase engines don't forget Petitjean's patented compound mallet. Not only will it pull more up the hill with less steam, but a 2-6-6-2 will go around a curve so sharp the headlight will shine over the hogger's shoulder. That is how Lucien Sprague tamed Morro Castle.
Bill Petitjean
