steam loco question

nw-mailing-list at nw-mailing-list at
Wed Jun 28 06:27:03 EDT 2006

...meaning of course that as the loco enters the curve, that the inside wheel lowers itself 1/8" on its flange, and the outside wheel climbs on its flange 1/8", you've gained that needed 1/4" in diameter on the outside drive wheel! Now, see why those tires are not flat, but are shaped like a cone? Also, ever wonder why the outside rails wear out much faster in a sharp curve? As my engineering professor used to say so simply, "Think about it."
Ben Blevins

nw-mailing-list at wrote:
Yes there is a taper with the inside of the driver being slightly larger in diameter than the outside. Does that work? Well, I did a little math last night taking a 56" diameter driver on a 1000' radius curve through 180 degrees. I won't do the math here but it turns out that the outside driver would have to make almost exactly one more revolution than the inside driver, or go about 14 feet further over better than 3000. So what diameter on the outside driver would do the trick? 56-1/4" !


From: nw-mailing-list-bounces at [mailto:nw-mailing-list-bounces at] On Behalf Of nw-mailing-list at
Sent: Tuesday, June 27, 2006 8:30 PM
To: nw-mailing-list at
Subject: Re: steam loco question

I won't repeat the answers given so far, which are all correct and well explained, but there's two more factors, as it's

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