Electric Bells and All About Them: A Practical Book for Practical Men

by Selimo Romeo Bottone

Fig. 91.

A glance at [Fig. 91] will render the whole system of wiring and connecting up with lifts and landing, perfectly clear. In connecting the branch lines to the main bare copper wires in the shaft, in order that the spoonbill springs should not interfere with them, they (the ends of the branch wires) must be bent at right angles, like a letter L, and the upright portion soldered neatly

to the back of the shaft wire. Any solder which may flow over to the front of the wire must be carefully scraped off to prevent any bumps affecting the smooth working of the contact springs. It will be evident on examination of [Fig. 91], that if any of the pushes on the landings be pressed, the circuit is completed between the battery at the top, through the two battery wires

to the bell and one of the indicators to the cab, and, on the other hand, that if a push be pressed in the cab, a corresponding bell on the landing will be rung, precisely as in [Fig. 87].

Some fitters employ a many-stranded cable to convey the current to and from the battery to the cab and landing, instead of the system of stretched wires herein recommended; but this practice cannot be advocated, as the continual bending and unbending of this cable, repeated so frequently every day, soon breaks the leading wires contained in the cable.

Fig. 92.

§ 74. In many cases where a "call" bell alone is required, the battery may be entirely dispensed with, and a small dynamo ([§ 15]) employed instead. The entire apparatus is then known as the "magneto-bell," and consists essentially of two parts, viz., the generator, [Fig. 92], and the bell, [Fig. 93]. The generator or inductor consists of an armature, which by means of a projecting handle and train of wheels can be revolved rapidly between the poles of a powerful magnet; the whole being enclosed in a box. The current produced by the revolution of the armature is led to the two binding screws at the top of the box. By means of two wires, or one wire and an earth circuit, the current is led to the

receiver or bell case, [Fig. 93]. Here, there are usually two bells, placed very near one another, and the armature attached to the bell clapper is so arranged between the poles of the double-bell magnets, that it strikes alternately the one and the other, so that a clear ringing is kept up as long as the handle is being turned at the generator.