Black American patentIn 1897, a U.S. patent for an improvement in "Casting Composite or Other Wheels" was issued to black American inventor E.R. Robinson (No. 594,286). It gave a method for casting wheels wherein the outer sides are of one metal and the interior portions are of another metal. The importance was not only to enable casting a metal of high electrical conductivity, such as brass, in a groove of an iron trolley wheel - but also to permit an entirely new contruction consisting of two outer disks or flanges and an intermediate, uniting portion, which extends from the contact portion of the wheel with a web extending to the centre and an integral bushing. Robinson also held a previous patent, issued four years earlier, for an "electric railway trolley."[Image: plan view of bottom section of a wheel three-part mold] |
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