Wednesday, April 20, 2011

Signal Bridge Project Update


In February I wrote about the idea of using a single track version of the signal bridge on the Southern Railway mainline in Cornelia to disguise the screen porch/ladder yard's train portal.






























This project recently made some progress! I found an LGB/Model Power traffic light/signal on ebay for a few dollars that is very close to the style of the one used by the Southern.

























































But when it arrived I was was disappointed to find the bulbs were cheap screw-ins with color flaking off and two of them blown. Rather than launch a hunt for obscure colored bulbs, I replaced all three with low voltage DC LEDs that I had on hand. At the same time I also replaced the feed wires that connected the signal to the included four position switch (all three colors plus "off"), replacing the ridiculously flimsy wires with solid 18 gauge stranded wire and plenty of heat shrink tubing, color coded to match the plastic wire cover with the lamp colors. At the same time I added a connector for a 9 volt battery and spade connectors, allowing E-Z power upgrades in the future. Finally, I shortened the brass tube that supports the signal by about half in order to more closely resemble the geometry of the one in used by the Southern.

With this overhaul the lamps in this signal will last forever, while allowing the convenience of low voltage DC wiring!































































Future Control Plans
While initially the four way control switch will be mounted in a box at the foot of the signal bridge, in the future I would like to separate the circuits such that the yellow and red lamps are controlled separately by two position toggle switches as follows:

The red lamp's switch would be mechanically linked to the track switch that controls access between the Arrival track and the Southern Railway's interchange track (found under the baggage car in the photo below). A train working the interchange fouls the 90 degree crossing that is directly outside the porch portal, so the signal would appropriately report immediate danger in the red position.

The green and yellow lamps will be controlled by the track switch that dictates whether a train continues around the Arrival track or crosses straight over the diamond and into the ladder yard (to the left of the observation car in the photo). If the switch is set for a train departing the porch to proceed up the line the signal will display green, yellow when set for the Arrival track.































Of course, I have no idea just exactly how to carry out the mechanical linkage between the Aristocraft track switch machine and an outdoor-grade toggle switch, but the idea and functionality of these lamps as a working signal makes the project too good not to continue chewing on!

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