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

160

UNITED STATES ASSOCIATION OF

[VOL. 8,

counteract the tendency to crack in the brackets from the expansion of the tread from heating by the application of the brake, is
the old double plate wheel. Many wheels of this pattern have
given great mileage; some master mechanics and superintendents
prefer them to any other form for engine truck wheels.
As a wheelmaker, I care not what the physical test is so that
it it is universal. While these tests do not make it certain that
each wheel in the lot is equal to the one tested, I have no doubt
it will prevent the use of many inferior and unsafe wheels. There
are many wheels now in use that would not have been put under
cars if this test had been required.
We show a twenty-eight inch wheel that had made eighty
thousand miles under an engine on a crooked road. We have
an old wheel in our shop now that was in use and was supposed
to have made five hundred thousand miles on the Erie road under
a freight car. Many of them have made a very great mileage.
Mr. HILDRUP. I fully believe with Mr. Lobdell that the double
plate wheel is the best; it is less liable to crack; it yields more
uniformly. But it costs fifty cents a wheel mnore to make. We
are making box cars carrying sixty thousand pounds load,
and the car will weigh thirty-five thousand pounds itself; and we
are running them at the rate of forty miles an hour. Twentyfive years pgo the maximum load was eight to ten tons, and there
was a fine put on if you got much above that. We are rapidly
developing a more perfect machinery, and you are not going to
neglect car wheels a great while longer. The five hundred and
fifty-pound wheel of to-day is a wonderful development.
Referring to the chills on car wheels Mr. Lobdell said: It is
well known that when certain kinds of molten iron are poured
against a metallic mold, that portion next to the mold becomes
hard, white, crystalline and brittle, while the interior portion remains gray, and more or less tough and fibrous. This conversion of the part that strikes the metallic mold into the hard, white,
crystalline metal is called "chilling." Different brands of iron
made from different kinds of ore, or from the same ore but under
different conditions of the furnace in which the ore is smelted,
possess greatly different chilling properties. This mainly depends
on the proportion of free carbon (graphite), silicon, sulphur, etc.,
and the proportion of these substances not only effects the depth