. Railway and locomotive engineering : a practical journal of railway motive power and rolling stock . he top revealing a miniature semaphorewith red arm on a white background. Alittle below this is an oblong openingcovered also with glass through which isvisible a card displaying appropriatewords, designating each operation. Atthe bottom of the box is a brass knobwhich is the handle of the plunger. The operation of signaling a trainthrough block A and consenting to itsentrance into block B may be briefly de-scribed as follows: Let us say that thesignalman at A desires to facilitate thepassage
. Railway and locomotive engineering : a practical journal of railway motive power and rolling stock . he top revealing a miniature semaphorewith red arm on a white background. Alittle below this is an oblong openingcovered also with glass through which isvisible a card displaying appropriatewords, designating each operation. Atthe bottom of the box is a brass knobwhich is the handle of the plunger. The operation of signaling a trainthrough block A and consenting to itsentrance into block B may be briefly de-scribed as follows: Let us say that thesignalman at A desires to facilitate thepassage of an express which we will callthe Southseeker, it is moving along thesouthbound track and A therefore pressesone of his electrical push buttons andgives three rings on the bell for the south-bound track in Bs tower. This causesB to respond by pulling out the handle ofthe plunger in his signal instrument onthe side of his tower adjacent to A. Thepulled out plunger is drawn back by aspring within the mechanism, and theaction of the man is transformed by elec-trical mechanism into the unlocking of. COLEMAN INSTRUMENT WltH CASING RE-MOVED SHOWING CARD, AND MIN-IATURE INDICATING SIGNAL. .^s home signal lever for the south-bound track. That collusion between Aand B or mistake upon Bs part is im-possible, with properly working appar- ,-ilus, is assured by the fact I! couldnot have pulled out his own plunger forthe southbound track unless the iiitcgrityof the track circuit had guaranteed theabsence of even a pair of wheels in little red semaphore arm behind the cir-cular glass at the top of Bs southboundinstrument falls to clear and B saysthank you by pressing his bell pushtwice. Now having his southbound home block 11, and, fnnliermore, the plunger lever unlocked through the courtesy of C, could not be pulled out and unlock thesignal lever at A unless both Bs distant southbound signals were inthe horizontal position. It is evident thatB can only unlock As southboundh
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Keywords: ., bookcentury1900, bookdecade1900, bookidrailwaylocom, bookyear1901
