Identifier: cyclopediaofappl05amer (find matches)
Title: Cyclopedia of applied electricity : a general reference work on direct-current generators and motors, storage batteries, electrochemistry, welding, electric wiring, meters, electric lighting, electric railways, power stations, switchboards, power transmission, alternating-current machinery, telegraphy, etc.
Year: 1916 (1910s)
Authors: American Technical Society
Subjects: Electric engineering
Publisher: Chicago : American Technical Society
Contributing Library: Northeastern University, Snell Library
Digitizing Sponsor: Northeastern University, Snell Library

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Fig. 199. Catenary System on Taght Brace Construction The catenary trolley-wire support has been developed to over-come this difficulty. As mentioned briefly before this system com-.prises a steel messenger wire securely mounted on insulators. Fromthe messenger wire, the trolley wire hangs by hangers located atintervals along the messenger wire. There may be any number ofthese hangers for each span of the messenger wire giving 3-pointsuspension, 5-point suspension, etc. By using hangers of differentlengths a trolley wire may be perfectly straight. 30S
Text Appearing After Image:
212 ELECTRIC RAILWAYS The insulators for the messenger wire may be mounted onbrackets, on span wires or on Ught bridge construction. All of theseforms of support are illustrated in Figs. 197, 198, and 199. Where sidewise stiffness is required, two messenger wires maybe used with hangers from each to the points of support of the trolleywire, Fig. 200. This is known as double catenary construction. THIRD=RAIL CONSTRUCTION The overhead trolley wire is not suitable for the transmissionof large currents to the cars as it is difficult to conduct such currentsthrough the small contact surface of trolley wheels. In such casesas require more than a very few hundred amperes, the distributionis through a steel conductor rail mounted alongside the track. Thecurrent is taken off through sliding shoes. Third=Rail Supports. The con-ductor rail or third rail ismounted either in the usualposition, base below and headabove, or inverted. Ordinarilythe rail used is the standardT-rail section and it may b

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