. Bulletin. Science. Figure lo.—Components of the steam passen- ger elevator at the time of its peak development and use (1876). (From The First One Hundred ^ Tears, Otis Elevator Company, 1953.) cables invariably were wound on a drum. The travel or rise of the car was therefore limited by the cable capacity of the winding drum. As building heights increased, drums became necessarily longer and larger until they grew so cumbersome as to impose a serious limitation upon further upward growth. A drum machine rarely could be used for a lift of more than 150 feet.^ Another organic difficulty exist
. Bulletin. Science. Figure lo.—Components of the steam passen- ger elevator at the time of its peak development and use (1876). (From The First One Hundred ^ Tears, Otis Elevator Company, 1953.) cables invariably were wound on a drum. The travel or rise of the car was therefore limited by the cable capacity of the winding drum. As building heights increased, drums became necessarily longer and larger until they grew so cumbersome as to impose a serious limitation upon further upward growth. A drum machine rarely could be used for a lift of more than 150 feet.^ Another organic difficulty existing in drum machines was the dangerous possibility of the car—or the counterweight, whose cables often wound on the drum—being drawn past the normal top limit and into the upper supporting works. Only safety stops could prevent such an occurrence if the operator failed to stop the car at the top or bottom of the shaft, and even these were not always effective. Hydraulic machines were not susceptible to this danger, the piston or plunger being arrested by the ends of the cylinder at the extremes of travel. THE HYDRAULIC ELEVATOR The rope-geared hydraulic elevator, which was eventually to become known as the "standard of the industry," is generally thought to have evolved directly from an invention of the English engineer Sir William Armstrong (1810-1900) of ordnance fame. In 1846 he developed a water-powered crane, utilizing the hydraulic head available from a reservoir on a hill 200 feet above. The system was not basically different from the simple hydraulic press so well known at the time. Water, admitted to a horizontal cylinder, displaced a piston and rod to which a sheave was attached. Around the sheave passed a loop of chain, one end of which was fixed, the other running over guide sheaves and terminating at the crane arm with a lifting hook. As the piston was pressed into the cylinder, the free end of the chain was drawn up at triple the piston speed, rais
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Keywords: ., bookauthorunitedstatesdepto, bookcentury1900, booksubjectscience
