. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . Epp Searching Fig. 189.—Christensen pneumatic selector searching. Figure 187 shows the iron framework with the selectors arranged inhorizontal rows, each row having space for twenty. Figures 188 to 190 are sketches showing the working method of Fig. —Christensen pneumatic selector connecting. Figure 191 is a diagram of the selector parts and circuits. The motive power consists of compressed air at two atmospheres or2 kg. per sq. cm. (29 lbs. per sq. in.) and is automatically maintainedb
. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . Epp Searching Fig. 189.—Christensen pneumatic selector searching. Figure 187 shows the iron framework with the selectors arranged inhorizontal rows, each row having space for twenty. Figures 188 to 190 are sketches showing the working method of Fig. —Christensen pneumatic selector connecting. Figure 191 is a diagram of the selector parts and circuits. The motive power consists of compressed air at two atmospheres or2 kg. per sq. cm. (29 lbs. per sq. in.) and is automatically maintainedby a reserve at an excess pressure of to kg. per sq. cm. A two- 14 210 AUTOMATIC TELEPHONY coiled electromagnet A opens a valve B which admits the compressedair into a cylinder and causes a piston to move onward (Fig. 188). Thesearch mechanism with the search magnet C and the searching contactroller D besides the necessary contact springs E are attached to the pistonrod. The return motion takes place by the aid of a watch spring F whenthe valve closes off the compressed air. In most selector constructions the motion ceases when tne motivepower (electrical current) is cut off, but in this selector the motivepower (air pressure) continues while the motion is stopped by a mechani-cal catching device. This is arranged in such a way t
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttelephone, bookyear19
