Identifier: bulletinunitedst2101956unit (find matches)
Title: Bulletin - United States National Museum
Year: 1877 (1870s)
Authors: United States National Museum Smithsonian Institution United States. Dept. of the Interior
Subjects: Science
Publisher: Washington : Smithsonian Institution Press, (etc.) for sale by the Supt. of Docs., U.S. Govt Print. Off.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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ications. In fact, however, the cylinder bore of the John Bullwas recently measured and found to be 11 inches. The strokeof 20 inches as cited by all is correct. Many changes, some minor and some major, were incor-porated in the John Bull during the next few years. The mostnoticeable was the addition of a 2-wheeled pilot, suggested in1832 by Robert L. Stevens to guide the locomotive aroundthe sharp curves common in the tracks of that era. In orderto attach the pilot to the front axle, the outside rods andcranks connecting the front and back axles had to be perma-nently removed, thus reducing the number of drivers fromfour to two. The John Bull has ever since been driven by onlythe two rear wheels (figure 30). The wheels of the pilot are29 inches in diameter. Another early permanent change was the replacement ofthe wooden-spoked wheels with those of cast iron. The oldwooden carriage-type wheels could not stand up under serv-ice in America, where sharp curves in the tracks prevailed. 41
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Figure 31.—Original wooden-spokedwheel of John Bull, in Notional Museum. A wheel, said to be one of the originals (figure 31) but lack-ing the flanged metal tire, was presented to the NationalMuseum (USNM 181194) by the Pennsylvania RailroadCo. in 1894. An inch or so less in diameter than 54 inches,the wheel would certainly be of the original size if the tirewere in place. The 14 spokes and the felloe are of wood.Metal bands, similar to the crank rings of the America (nowaffixed to the reconstructed wheels of the restored StourbridgeLion, see p. 20), are included in the construction of this oldwheel o^xhc John Bull. Whether or not it is one of the original wheels applied tothe locomotive by Stephenson can not at this time be def-initely proved. Possibly it is an early wooden-spoked wheelbuilt and tried by the Camden and Amboy prior to theadoption of the all-metal wheels now on the locomotive. An-other similar wheel, until recently located in the Pennsyl-vanias library in its Suburba

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