Title: Bulletin
Identifier: bulletin228smit (find matches)
Year: 1961-1962 (1960s)
Authors: Smithsonian Institution; United States. Dept. of the Interior; United States National Museum
Subjects: Science
Publisher: Washington, Smithsonian Institution Press, (etc. ); for sale by the Supt. of Docs. , U. S. Govt Print. Off
Contributing Library: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library
Digitizing Sponsor: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
Figure 8.—In the typical steam elevator machine t\vo vertical cylinders were situated either above or below the crankshaft, and a small pulley was keyed to the crankshaft. In a light-duty machine, the power was trans- mitted by flatbelt from the small pulley to a larger one mounted directly on the drum. In heavy-duty machines, spur gearing was interposed between the large secondary pulley and the winding drum. (Photo courtesy of Otis Elevator Company.) THE STEAM ELEVATOR The progression from an elevator machine powered by the line shafting of a mill to one in which the power source was independent would appear a simple and direct one. Nevertheless, it was about 40 years after the introduction of the powered elevator before it became common to couple elevator machines di- rectly to separate engines. The multiple belt and pulley transmission system was at first retained, but it soon became evident that a more satisfactory service resulted from stopping and reversing the engine itself, using a single fixed belt to connect the engine and winding mechanism. Interestingly, the same pattern was followed 40 years later when the first attempts were made to apply the electric motor to elevator drive.
Text Appearing After Image:
Figure g.—Several manufacturers built steam machines in which a gear on the drum shaft meshed directly with a worm on the crankshaft. This arrangement eliminated the belt, and, since the drum could not drive the engine through the worm gearing, no brake was neces- sary for holding the load. (Courtesy of Otis Elevator Company.) By 1870 the steam elevator machine had attained its ultimate form, which, except for a number of minor refinements, was to remain unchanged until the type became completely obsolete toward the end of the century. By the last quarter of the century, a continuous series of improvements in the valving, control systems, and safety features of the steam machine had made possible an elevator able to compete with the subse- quently appearing hydraulic systems for freight and low-rise passenger service insofar as smoothness, control, and lifting power were concerned. However, steam machinery began to fail in this competition as the increasing height of buildings rapidly extended the demands of speed and length of rise. The limitation in rise constituted the most serious shortcoming of the steam elevator (figs. 8-10), an in- herent defect that did not exist in the various hydraulic systeins. Since the only practical way in which the power of a steam engine could be applied to the haulage of elevator cables was through a rotational system, the PAPER 19: ELEVATOR SYSTEMS OF THE EIFFEL TOWER 552119—61 2

Note About Images