. Bulletin. Science. Figure 11.—Armstrong's hydraulic crane. The main cylinder was inclined, permitting gravity to assist in overhauling the hook. The small cylinder ro- tated the crane. (From John H. Jallings, Elevators, Chicago, 1916, p. 82.) of a 3-to-l tackle, with the effort and load elenients reversed. Simple valves controlled admission and exhaust of the water. (See fig. 11.) The success of this system initiated a sizable industr in England, and the hydraulic crane, with man modifications, was in common use ther e for man years. Such cranes were introduced in the United States in about
. Bulletin. Science. Figure 11.—Armstrong's hydraulic crane. The main cylinder was inclined, permitting gravity to assist in overhauling the hook. The small cylinder ro- tated the crane. (From John H. Jallings, Elevators, Chicago, 1916, p. 82.) of a 3-to-l tackle, with the effort and load elenients reversed. Simple valves controlled admission and exhaust of the water. (See fig. 11.) The success of this system initiated a sizable industr in England, and the hydraulic crane, with man modifications, was in common use ther e for man years. Such cranes were introduced in the United States in about 1867 but never became popular; they did, however, have a profound influence on the elevator art, forming the basis of the third generic type to achieve widespread use in this country. The ease of translation from the Armstrong crane to an elevator system could hardly have been more evident, only two alterations of consequence being- necessary in the passage. A guided platform or car was substituted for the hook; and the control valves were connected to a stationary endless rope that was accessible to an operator on the car. The rope-geared hydraulic system (fig. 13) appeared in mature form in about 1876. However, before it had become the "standard elevator" through a process of refinement, another system was introduced which merits notice if for no other reason than that its popularity for some years seems remarkable in view of its preposterously unsafe design. Patented by Cyrus W. Baldwin of Boston in January 1870, this system was termed the Hydro-Atmospheric Elevator, but more commonly known as the water-balance ele- vator (fig. 12). It employed water not under pressure but siinply as mass under the influence of gravity. The elevator car's supporting cables ran over sheaves at the top of the shaft to a large iron bucket, which traveled in a closed tube or well adjacent to and the saine length as the shaft. To raise the car, the operator caused a valve to open, fil
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