Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems (1921)
Smith, Arthur Bessey, b. 1875, Campbell, Wilson Lee · New York : McGraw-Hill · leaf 230
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 theselector. … Fig. 190.-—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 0.9 to 1.1…
Telephone
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