. Bulletin. Science. Figure 13.—Vertical cylinder, rope-geared hy- draulic elevator with 2 : i gear ratio and rope control (about 1880). For higher rises and speeds, ratios of up to 10:1 were used, and the endless rope was replaced by a lever. (Cour- tesy of Otis Elevator Company.) 1^ possible with mechanical means. Cars with lever control could be run at the high speeds required for high buildings, yet they could be stopped with a smoothness and precision unattainable earlier with systems in which the valves were controlled by an endless rope, worked by the operator. It was almost completely
. Bulletin. Science. Figure 13.—Vertical cylinder, rope-geared hy- draulic elevator with 2 : i gear ratio and rope control (about 1880). For higher rises and speeds, ratios of up to 10:1 were used, and the endless rope was replaced by a lever. (Cour- tesy of Otis Elevator Company.) 1^ possible with mechanical means. Cars with lever control could be run at the high speeds required for high buildings, yet they could be stopped with a smoothness and precision unattainable earlier with systems in which the valves were controlled by an endless rope, worked by the operator. It was almost completely silent, and when the cylinder was placed vertically in a well near the shaft, practically no valuable floor space was occupied. But most im- portant, the length of rise was unlimited because no drum was used. As greater rises were required, the multiplication of the ropes and sheaves was simply increased, raising the piston-car travel ratio and permitting the cylinder to remain of manageable length. The ratio was often as high as 10 or 12 to 1, the car moving 10 or 12 feet to the piston's 1. In addition to its principal advantages, the hydraulic elevator could be operated directly from municipal water mains in the many cities where there was sufficient pressure, thus eliminating a large investment in tanks, pumps and boilers (fig. 14). By far the greatest development in this specialized branch of mechanical engineering occurred in the United States. The comparative position of Amer- ican practice, which will be demonstrated farther on, is indicated by the fact that Otis Brothers and other large elevator concerns in the United States were able to establish offices in many of the major cities of Europe and compete very successfully with local firms in spite of the higher costs due to shipment. This also demonstrates the extent of error in the oft-heard statement that the skyscraper was the direct result of the elevator's invention. There is no question that continued elevator i
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Keywords: ., bookauthorunitedstatesdepto, bookcentury1900, booksubjectscience
