This has probably been disucssed in back issues of Live Steam magazine, since there have been numerous locomotive construction articles over the years and this problem would have (or should have) come up for every one of them.
An e-mail to Neil might yield some results.
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Don't believe everything you know. -- Bumper sticker
Everybody is ignorant, only on different subjects. -- Will Rogers
Law of Logical Argument - Anything is possible if you don't know what you are talking about.
If at first you don't succeed, try, try, again. Then give up. There's no point in being a damn fool about it. -- W.C. Fields