Re: Beating the Snot out of the Railhead, with Class. - Makes you wonder

kcsivils Wrote:
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> What an impressive machine! It's a shame the
> Grande never built a similar class in 3 foot
> gauge. I doubt though the Grande's roadbed and
> track could withstand a snot beating like that!
>
> Still, the San Juan/Shavano would have arrived
> ahead of schedule if the track could have taken
> it.

Interestingly, the Grande's track itself could very much have handled the NZR engines (gauge incompatibility notwithstanding, I'll get to that in a moment). Rail weights were similar between the two networks. The NZR 4-8-4's have a maximum axle load lower than that of the D&RGW heavy narrow gauge mikados, and the NZR engines are only slightly higher in maximum overall weight (spread over two additional axles). The NZR engines have better counter-balance, wouldn't pound as hard at equivalent speed, and also track straighter without the side-to-side hunting that characterizes the D&RGW's big mikes. The fact that the NZR engines are cape gauge isn't so much of an issue when you consider that the loading gauge they were built to is quite limited: Both height and width are less than was permitted on the D&RG narrow gauge. Hence the NZR engines could've been built to 3 foot gauge just as readily; in this case 42 inch gauge was simply the standard British commonwealth narrow gauge and chosen mostly for that reason rather than any specific advantage conveyed by 42 inch rail width. Case in point, some of the NZR's early steam classes imported from the U.S. were in essence modified 3 foot gauge designs.

Problem the Grande would've had with that type of engine would've been length--it's quite long and would not have fit turntables/etc. Maybe not some roundhouse stalls either. The curves encountered on the D&RG narrow gauge might've been a problem too, being much tighter than what were normally encountered on NZR's routes. The driving wheelbase of the NZR engines is over 14 feet versus a couple feet less on the D&RG 2-8-2's. On the other hand, the Brazilian ALCO 4-8-4's of basically similar size managed sharp curves so that wasn't an insurmountable problem by the 1930's. The D&RGW did investigate potentially acquiring 4-8-2 types with 4 foot driving wheels but decided to stick with 2-8-2's instead mostly to keep the length to a minimum.

I guess all the above is a way of saying if the D&RGW had wanted such engines, it could have had them. It didn't need them for the conditions encountered on its by-then unwanted and shrinking narrow gauge network and wasn't interested in doing the necessary infrastructure upgrades to support them. As such the NZR engines are something of a study in what could have been had the narrow gauge movement taken more of a root stateside.