I’m currently planning to use PRR-Style Colored PCL Signals for my Layout, Does anyone have any kind of diagram for these? I’m planning to 3D model and print them.
PRR did not use CPLs; that was a B&O (Patenall) innovation. The wiring logic is no different from any tricolor signal, with ‘red’ to the two horizontal bulbs, ‘amber’ to the two at 45 degrees, and ‘green’ to the vertical. There is no mechanical drive as in a semaphore.
The original (‘tombstone’) PRR position lights had four bulbs per aspect, and the aspects crossed over strangely, so you’d need more custom wiring than the results probably justify. I cheated a bit when doing the classic three-bulb type by just leaving the center bulb always lit; the horizontal, angle, and vertical aspects can then be wired just for CPLs but of course only using the right single color of bulb.
Probably by now someone has manufactured very small or SMD LEDs with the ‘correct’ phosphor color for PRR position lighting, which is influenced by material in the pointed glass lenses of the ‘real thing’. If you can’t find them you’d have to use radio dial dye or other transparent material like that used for fake stained glass to get the right color, and turn the lenses with a drill and files/sandpaper/lapping film from transparent rod stock.
Norfolk and Western, which was controlled by PRR, experimented with red horizontal aspects on otherwise-PRR-style position lights in the 1950s, and I believe there were some places on PRR Lines West where this was done. I always assumed this was red bulbs in the ‘horizontal’ position, but that wouldn’t account for the center bulb. I am quite certain that Ed will have PRR diagrams that show how the trick was done.
Amtrak on the present NEC uses a CPL style comparable to B&Os, with smaller LED lights and I think smaller heads. Surely there is someone who makes signals or parts for these in popular scales…
The usage of positional signals by the PRR and later the B&O actually was a great move. There was no way to confuse the signal aspect even if you were colorblind as long as you could see the lights ypu knew what the indication was.
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Only the two outer horizontal red bulbs lit up for the stop aspect.
Source : we used to have one or two of the red eye interlocking signals. I don’t know if they were put in place by prr or later converted by subsequent rrs.
Thanks!
I have quite a few Pennsy position light signals on my layout. Most I made from Oregon Railway Supply parts. Yes, a little oversize but quite effective.
PRR_7125-Queen Mary-1 by Edmund, on Flickr
I seem to recall a discussion on the PRR.io list that the red roundels for ‘absolute’ stop began to be implemented around 1947 or so. I’d have to check.
PRR_position-light by Edmund, on Flickr
Presently I am working on some Dwarf PLs using 0403 LEDs:
There are dozens of PRR Standard Signal Plans to be found on some of the Pennsy sites:
Also look into the ‘Keystone Modeler’ online magazine. Lots of help for the Pennsy Modeler.
The example above is the issue where I found much of my dwarf PL info.
Good Luck, Ed
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As originally installed the PRR’s Position Light Signals did not have ANY color component. All indications were done with the yellowish-white bulb in every light position in the signal. Dipalys were either Vertical, Horizontal or Diagonal to both the right and left as well as having a second display head.
It wasn’t until the late 1960’s or early 70’s that a program was started to display Red in the horizontal display on the signals. I don’t know if that was a PRR or Penn Central initiative.
Like PC could afford red light bulbs.
They probably piggybacked the order Bevan placed for the Executive Jet Aviation ‘hostesses’.