> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:sslivesteam-
> [EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]

> My understanding of wheel taper (And I may be full of B.S., but this is
what
> I have read) is to allow trains to navigate curves without excessive wheel
> slip. As centrifugal force causes the wheel set to move to the outside of
the
> curve the larger diameter of the tread is contacting the rail  on the
larger
> diameter, while the inner wheel is riding on its smaller diameter.  This
> lessens wheel slip and I presume that on 1=1 scale (full size) that
railroads set
> minimum curve radius to suit on mainline practice.

Basically that is true, but the difference in diameter over a 3 degree taper
of a wheel a couple inches in diameter is negligible. And, since most garden
lines use brass or nickel silver rail, that would wear long before the wheel
tread wore! The amount of wheel slip due to now using wheels of constant
diameter wasn't enough for "real railroads" to bother with coned treads
anymore. Class 1 roads use a spiral leading into the curve and
superelevation to eliminate the wheel slip issues.

 Look at the  steep taper on
> a Lionel 027 wheel compared to the slight taper on a fine scale  wheel.

Tinplate is an entirely different application, as they run on tubular rail,
not rail of scale profile. The wheel tread is actually the flange on Lionel
trains.

Basically if you want to put a 3 degree taper on the wheels for accuracy
reasons...fine. But to a beginner building his first steam locomotive
doesn't need to worry if his wheel are EXACTLY a three degree taper. In
fact....if he builds his locomotive with parallel wheel treads, it will run
and track as well as those with a three degree taper. The reason real
railroads have eliminated the coned tread of locomotives is traction. The
contact are is greater when the wheel is contacting the rail across the
whole tread, where as the cone wheel has a very tiny contact area, which
gives you a MUCH better chance to slip! For me....I'll take all the traction
I can get on my models.

Keith

> 

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