The practical telephone handbook and guide to the telephonic exchange (1906) (14753797364)

Identifier: practicaltelepho00pool (find matches)

Title: The practical telephone handbook and guide to the telephonic exchange

Year: 1906 (1900s)

Authors: Poole, Joseph

Subjects: Telephone

Publisher: New York, Macmillan Co.

Contributing Library: Northeastern University, Snell Library

Digitizing Sponsor: Boston Library Consortium Member Libraries

Text Appearing Before Image:

Fig. 167.—Scale f the lifting of the drop shutter into its normal position. Thereare a large number of varieties of these instruments, the SWITCH-BOARD APPARATUS I5i simplest being those having a kind of cam projection on thefront of the drop shutter, which, when the plug is inserted inanswer to a call, is lifted upward by an enlarged collar on theplug, so as to carry the shutter to its normal position, as shownin Fig. 167. Another form of this kind of apparatus is shown in Fig.168, in which the bottom long-line spring of the spring-jack ahas a kind of stirrup loop formed on its end. This is bent up-ward so as to intervene between the end of the ironclad magnetand the drop shutter d. The shutter has attached a pro-jecting-piece, which passes to the back through a hole in theframe-piece f, so that when the shutter falls the projecting

Text Appearing After Image:

Fig. 168 piece passes inside the top of the stirrup loop. When theanswering plug is pressed into the j ack, the sleeve of the plugforces down the spring a, and the stirrup loop moving downwith it, bears on the shutter projection, and raises the shutteruntil it is held by the armature-lever catch c. These instru-ments are made by the American Electric Telephone Co. In another form the end of the plug on entering the jackcarries or presses back a lever or rod, having a projection atthe front of the shutter which lifts the latter into position. These combined jacks and plugs are very convenient ar-rangements; as, from the fact that the answering jack isdirectly beneath the drop, the operator is immediately guidedto the right jack without any mental effort, so that time issaved and there is no risk of mistake. Spring-Jacks.—These are now very important adjuncts to 152 PRACTICAL TELEPHONE HANDBOOK the telephone, being used on nearly all kinds of switch-boards.They are very varied in form

the practical telephone handbook and guide to the telephonic exchange 1906 book illustrations history of technology electric power telephone images from internet archive

1906

Northeastern University, Snell Library

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public domain