Automatic block signals and signal circuits: American practice in the installation and maintenance of signals electrically controlled, and operated by electric or other power, with descriptions of the accessories now regarded as standard
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ampere ampere-hour armature contacts arrangement automatic back contact binding posts block causes caution position cell circuit breaker circuit controller circuit-breaker clear position clutch magnets coils common line condition connected copper copper element current passes danger position dashpot deenergized device diagram direct current disk distant blade distant semaphore distant signal east-bound electromagnet energized fastened front contact function gear hence home and distant home blade home semaphore home signal indication magnet insulated interlocking latch latter lever line wires line-wire lock magnet magnetic circuit main battery mechanical motion moving neutral armature normal clear normal danger normal position occur ohms open-circuited operated phore pivoted polarized relay pole changer prevent rail lengths reverse roller sema shaft shown in Fig shunt side slot magnet slow releasing stop position switch instruments three-position thrown tion track battery track circuit track relay track section unlocking voltage west-bound zinc zinc sulphate
Page 4 - D^ sition approximating thirty degrees from the vertical it will indicate the same as though at the full horizontal position. This is effected by using several spectacles, each held in place by independent bezel rings, or by so-called continuous light spectacles. Semaphores vary in length from four to five feet, about four and one-half being regarded as standard.
Page 3 - If thsee be automatic track relays properly interconnected, they can be readily arranged to give the protection desired. If they be semi-automatic, electric interlocking will be introduced to prevent confliction of routes. Thus, when signal 3 is at clear, to allow a south bound train to pass, 2, and 4, must be locked in the normal or stop position when electric locking or interlocking is used and prevented moving to clear if the ordinary automatic system be employed.