Locomotive Wheelbase

[nw-mailing-list at nwhs.org]

A query for Ed King :  If, as Ed says,  rigid wheelbase is not a factor in
the
ability of a steam locomotive to negotiate track curvature, then why is it
that
when  Baldwin  Locomotive Works produced Decapod  2-10-0    class
locomotives, they left the third, or middle drive wheel flat all the way
across
without a flange?     Bill Sellers