. Das Telefonsystem der britischen Post. Ein praktisches Handbuch. gs sind so nach innen gebogen, dass das dreieckige, am Schlüssel befestigte Ebonit-Stück sie beim Drücken nach außen drückt, wo sie mit den äußeren oder Generatorfedern in Kontakt kommen. Die langen inneren Federn sind jeweils an die Spitze und Schulter des roten Zapfen angeschliessen. Die Bolzen sind mit den entsprechenden Bolzen des schwarzen Ringschlüssels verbunden, dessen Innenspringemit der Spitze und Schulter des schwarzen Stiftes verbunden sind. Die Außenspringedes schwarzen Zapfen sind mit t verbunden
909 x 2751 px | 7,7 x 23,3 cm | 3 x 9,2 inches | 300dpi
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. The telephone system of the British post office. A practical handbook . gs are curved inwards in such a manner that when the key isdepressed the triangular-shaped piece of ebonite which is attached to therod of the key pushes them outwards, where they come into contact withthe outer or generator springs. The long inner springs are connedted tothe tip and shoulder of the red peg respectively. The studs are connectedto the corresponding studs of the black ringing key, whose inner springsare connected to the tip and shoulder of the black peg. The outer springsof the black peg are connected to the ringing battery. 8o Connection of Ringing Keys. The connections of a pair of cords and ringing keys are shown inFigure 68. Depression of the black key connects the battery springs tothe peg springs; thus the negative pole of the battery is connected to thatip of the peg which comes into contact with the A line. The positive isconnected to the B line ; thus it will be seen that the ringing battery isjoined in series with the distant main permanent current. Similarly, . 1)6, 1 ■U m ijf ^ ■if sj/ o *>UT£i> Sfftines ^ ouTKn s//tmaeo* m-H^n at./teK o* o-ntet) nee Figure 68.depression of the red peg connects the generator to the tip and shoulder.In the normal condition the tip of the black peg is connected to the tipof the red peg, and shoulder to shoulder. The connection between theinner studs is also joined to the ring-off indicators and to the speaking key.The battery is teed along to all the outer springs of the black keys, andthe generator is similarly connected to the outer springs of all the red A key is attached to each pair of cords which, when thrown forward, puts the operators speaking set across the cords at the point indicated Compute Operating Connections. 8i in Figure 68. The general form of the key consists of six springs andfour studs; in fact, is very similar to two ringing keys placed side by side, but operated by one lever. The triangular piece of ebonit
