RAILWAY SIGNALS

Dominion, Volume 7, Issue 2166, 3 June 1914, Page 8

RAILWAY SIGNALS

main mm colusm TRIAL OP THE SEMAPHORE MR. FRAZER, ML, PIiESEN? HOW THE MECHANISM WORKS (Br Telesriwh.—Frees Association.) AuGblitiUi, Juno 2. A practical demonstration of sciKaphorc signalling was niatlo ;te-<lay tor tho information of Mr, F. V, Fmer, S.M., who-is conducting tiie inq-n-est regarding the railway disaster on Wednesday. Counsel for ramus interested persons were also present, five inquest will bo resumed on Jaiuj 10, and'evidnnco will tlieti bo given that, shortly after- tlio acckJent, tlso signal lover was looked in tlio danejcT position, but tiio signal itself was green for "All deal , ," Attention was given principally to the. manner m.-ivfireh the strtniipJso.ro operates at night. Situation of Signal. '

There is only one signal south of Whangama.rino, -and it was upon this that tho driver o£ the express train hnd to rely iii app-roaefa-ing tho station. Tlio length of track between the esntas of tho station platform and tho signal is 6U4 yards, and the signal, is fixed 30ft. aliove the rail level on a post situated 35ft. from tiie centre of tlio track. Tlio signal stands at tho junction of two gradients, for tlio line rises toward tlio sign.i!, and curv*« into a clesconding gradient towatds tho station. In the position selected for its the signal is visible from .the preceding mils or track. LevSr to semaphore, " Tho actual length of wire connection between the lever and the signal (including short pieces of chain passed round grooved pulleys to change tho direction of the wire) is about 10 yards greater, so that tiic connection is formed by aboat 014 yards of steel ivirc, scvcn-eiglitlis of an inrh ill circumference. Tho direct distance from tho signal levcf to tint points switch at which tlm tablet porter, William Donaldson, Tvns engaged when tlio disaster occurred, k nearly 5C feet.

■Semaphore Mechanism. The semaphore signal consists of mi armor blade which is pulled clown or "off" to incKchto . that a train'may pass ,in tho lioracnta.! or "on" position. Fixed ta tlio runner end of the blado is a frame containing .rail ami green glasses, which moves with the blade beforo a lamp, «► that, at night, red is shown for dinger end-areen for "Go ahead," or "AH clear,". Tho frame holding tho coloured glasses is roughly kidney shape:], and tho device is tiwuvn as tho "spectacle." A partial inftvoracnt of tho semaphore tvill give a fni) 'green signal which, in darkness, obscuring the indication of t-ke swmftphore, vrould appear exactly tlio same as if tlie signal had boan moved tlio maximum distance. Experiment has shown that the draw required at Wits lever to <le> press fnlly .tbo sctnapliore of Whangamarino signal is <»!?v« inches, but this draw is only seven inches at tho foet of the post. The l.s«fsr end ttw Lights, Experiments made at yesterdays demonstration showed tilat a draw of only tlir-eo inches moved tlia "spectacle" ciiougli to show fnli grocu. 'ijtc rod or green signal is not visible to i'l e officer operating the sigusl. His euly guide to tho position <rf the signs! is a small white light sinning through' tlie hack of the lamp, iV.rt of tho apparatus is an iron shutter, which, moving' with tiro "spectacle," qWuros this ivhitc light. Tlio latter is visible only when tho semaphore is henaeiital, and the signal showing full red. A very slight movement of the central axis moves the elurtter sufficiently to obsenro tljo. white light completely, and., when the signal h being pulled "off" at might, tlie white light disappears lonjj before tlio green shows from the otiip- side. Thero is a weM-lcuown ruto that tlie absence of u signal, where a signal is ordinarily shown, must b© treated as a danger signal, and iriien a signalman cannot perceive tJws whites light of a signal which should bo at "Danger," it becomes his dnijf to ascertain vrhetlwr tho lamp is extinguished or* the. signal out of order. The ebseirniiion of tire white light by a fractional movement of the signal is designed as a guard against'an jinpfopei- display of tho "ail clear" signal, and is ceinpleto long boforo the full green shows. Tho Repeater* There is an electrical device known as tho "repeater, 1 * vfliich is employed iit connection with signals that arc bttyoftd the range of tho signalman's vision. Its indicators change from "danger" to "clear" only wjion tko seiaajjliaro has been completely Assessed* send the "danger" iiwlieaior is restored by ilte least upward movement of the anu v Tt)is devico was not in use at \fharjganisriiio. ■