I'm not sure a larger diameter wheel puts that much more surface on
the rail, all things being equal, and not being a mechanical engineer.
I do know this, though; old timers told me that a nickel against the
wheel tread on a locomotive such as 4-8-4 ATSF 2913 was enough to
stall the locomotive which, because of its weight, could not climb
over the nickel. I have no first hand experience, however.
Bob Nicholson (Duct tape over mouth!)
____________________________________________-
--- In [email protected], "ed_loizeaux" <[EMAIL PROTECTED]> wrote:
>
>Suffice to say, that I am still in learning mode
> trying to figure out why a large-wheeled loco (steam) has more drawbar
> pull than a small-wheeled loco (dismal) when they both have the same
> weight and the same number of powered wheels. One fellow suggested
> (offlist) that the larger diameter wheel has more surface area contact
> with the rail head which then results in more drawbar pull.
> Interesting theory, but I cannot say if it is really the causation
> factor in this instance. Any mechanical ungineers out there? Or
> metallurgists? Or maybe someone willing to take an unscientific
> guess? Nothing like a new challenge to end the day. Cheers...Ed L.
>
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