Cast-Iron Car Wheels. [Volume: 8, Issue: 3, 1889, pp. 153-170]

162

UNITED STATES ASSOCIATION OF

LVOL. 8,

chilled portion has the effect claimed, then it would be impossible
to make a large roll with a perfect chill.
The character, depth and degree of hardness depends on the
proportion of carbon, silicon, phosphorus, etc. This change or
chilling, produced by sudden cooling, no doubt takes place in a
very short time, and is not afterwards affected by any degree of
heat much below the point of fusion, and judging from my experience in casting chilled rolls I should say that it is not affected
by. being in contact with the liquid iron in the interior of the casting while this is in a quiescent state.
Heating chills by steam or otherwise is not new. All chilled
rolls are cast in heated chills. In 1862 a patent was granted for
chills or molds in which railroad wheels are cast, heated by means
of steam, hot air, etc., introduced into an annular space formed in
the chill.
Mr. CHAPIN. We had a case the other day of a car of material coming into our yard overloaded. It was in a twelve and-ahalf ton car, and when we weighed it and the empty car we found
that there had been twenty-eight tons in a twelve and-a-half ton
car.
Mr. HILDRUP. A broken wheel is a very expensive tiling.
We know the best of wheels will crack under certain conditions,
and if the inspector don't find them there will ultimately be a
broken wheel. To me it is oftentimes a question how it is possible for cast-iron to meet the strain that is put on it. By increasing the thickness of the tread, by that means allowing a greater
chill and a harder chill, we impair the safety of the wheel. All
railroad wheel makers know that a hard plate, a plate approaching mottled or white iron, will be brittle. We know that metal
in certain conditions, in a s'.nd mold, will chill a certain thickness; seven-eighths is alarge provision for safety against any hardnessor brittleness of plates, and again it is providing metal that
any careful mechanic will see is well applied; it is well applied
for safety, and I fully believe. that inside of five years, and probably inside of two years, 650 pounds will be considered the desirable standard for wheels for a thirty-ton car.
Mr. i.. GRIFFIN. We have manufactured cast-iron wheels for
many years, have given careful attention to the results obtained
from them and to their possibilities. Our experience and inves