. Bulletin. Science. Figure i6.—English direct plunger hydraulic elevator (about 1895). (From F. Dye, Popular Engineering, London, 1895, P- 280.) in proportion to its loading. The direct-current motor of the 1880's was easily capable of such service, and it was widely used in this way. Adaptation of the motor to the direct drive of an elevator machine was quite another matter, the difficulties being largely those of control. At this time the only practical means of starting a motor under load was by introducing resistance into the circuit and cutting it out in a series of steps as the speed pi
. Bulletin. Science. Figure i6.—English direct plunger hydraulic elevator (about 1895). (From F. Dye, Popular Engineering, London, 1895, P- 280.) in proportion to its loading. The direct-current motor of the 1880's was easily capable of such service, and it was widely used in this way. Adaptation of the motor to the direct drive of an elevator machine was quite another matter, the difficulties being largely those of control. At this time the only practical means of starting a motor under load was by introducing resistance into the circuit and cutting it out in a series of steps as the speed picked up; precisely the method used to start traction motors. In the early attempts to couple the motor directly to the winding drum through worm gearing, this "notching up" was transmitted to the car as a jerlving motion, disagreeable to passengers and hard on machinery. Furthermore, the controller contacts had a short life because of the arcing which resulted from heavy starting currents. In all, such systems were unsatisfactory and generally unreliable, and were held in disfavor by both elevator experts and owners. There was, moreover, little inducement to over- come the problem of control and other minor prob- lems because of a more serious difficulty which had. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Smithsonian Institution; United States. Dept. of the Interior; United States National Museum. Washington, Smithsonian Institution Press, [etc. ]; for sale by the Supt. of Docs. , U. S. Govt Print. Off
Size: 1182px × 2114px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorunitedstatesdepto, bookcentury1900, booksubjectscience
