Paul
Hillman wrote:
A few days ago there was a discussion about the purpose of ribbed back
wheels, and the answer was the "ribs" were there for cooling during forming
- casting of the iron wheels. But, when did we see ribbed-backed wheels
disappear from the rails? Apparently the "ribs" went away with the use of
steel in wheel making.
Not sure what discussion you reference. But it is simply
NOT true that the ribs had anything to do with cooling. They are there to
strengthen AND stiffen the wheel. Later analysis showed that the effect is not
large, so simple wheel plate shapes have been used ever since. The casting
process can be used to make either kind of wheel, whether the wheel is cast
iron or cast steel, so the ribs have nothing to do with whether they are iron
or steel.
Chilled iron wheels are cast with chills at the wheel
tread to improve performance of that area. That process has nothing whatever
to do with ribs. Railroads realized as early as 1930 that steel wheels
provided better durability, but also cost more, and moreover were often in
short supply. Especially after World War II, railroads placing orders for new
cars with wrought steel wheels had to accept part or all of the order with
cast wheels, because production of wrought wheels could not keep
up.
My basis for this is not only my professional
experience in both academic and industrial metallurgy, but my multi-year
experience on the AAR Research Committee, involved in research on materials
for both rail and wheels, including meetings at the AAR Research Facility near
Pueblo, Colorado (now the Transportation Technology Center). Believe me, we
covered wheel production and wheel materials to exhaustion.
Tony Thompson
2906 Forest Ave., Berkeley, CA
94705
(510) 540-6538; fax, (510)
540-1937;
