The recent discussion of the DL&W signal system raised two questions in my mind; perhaps someone on the list might be able to illuminate. First – did any other railroad use the 2-head / 4-light RYYG system, or was it as unique to the DL as CPL’s were to the B&O? Second – most signal systems are “fail safe”, in that a bulb that fails to properly light up causes a train to receive a more restrictive indication. However, under the DLW system, there is one case where a failure might cause a less restrictive indication to be displayed. I.e., when a clear medium is intended at an interlocking for a diverging move, the train should see a lit-up red in the top head over a lit-up green in the bottom head. However, if the red on the top head were to fail but the green on the bottom head were to light up, the train would see a dark upper head and a lit green lower head, which indicates “clear”, as if a straight move through the interlocking were intended. A train could then arguably enter a diverging route at too high a speed. I would imagine that the DLW made some provisions in its signal wiring to prevent this, e.g. putting the top red light and bottom green light in series so that if one didn’t work, the other wouldn’t either (of course, two dark heads would be taken as a STOP). Just wondered if anyone knew how this was handled. Jim Gerofsky _________________________________________________________________ Share life as it happens with the new Windows Live. http://www.windowslive.com/share.html?ocid=TXT_TAGHM_Wave2_sharelife_122007 The Erie Lackawanna Mailing List http://EL-List.railfan.net/ To Unsubscribe: http://Lists.Railfan.net/erielackunsub.html ------------------------------
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