We show herewith the method employed by the Baltimore Car Wheel Company
in casting chilled wheels to prevent tread defects. The ordinary mode of
pouring from the ladle into the hub part of the mould, and then letting
the metal overpour down the brackets to the chill, produces cold shot,
seams, etc. In the arrangement here shown the hub core, A, has a concave
top, B, and the core seat, C, is convex, its center part being lower than
the perimeter of the top of the core. Figs. 3, 4, show the core, A, in
the side elevation and in plain. Fig. 2 is a core point forming a space
to connect the receiving chamber, E, above, with the mould by
passageways, D D, formed in the side of the top of the core. The combined
area of these passageways being less than that of the conduit, F, from
the receiving chamber, the metal is skimmed of impurities, and the latter
are retained in the receiving chamber, E. The entering metal flows first
to the lower hub part at H H, thence by the sprue-ways, G G, to the lower
rim part at J J, being again skimmed at the mouth of the sprue-ways. Thus
the rim fills as rapidly as the hub, and the metal is of a uniform and
high temperature when it reaches the chill.
[Illustration: CASTING OF CAR WHEELS.]
In the wheels made by this firm, every alternate rib is connected with
the rim, and runs off to nothing near the hub; the intermediate ribs are
attached to the hub, and diminish in width toward the rim.--_Jour.
Railway App._
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