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Maybe I should have been more specific.There's a lot of data on that diagram and I don't know what most of it means. 12R, 10R, 4E, 2E, 11, 15... What is all that?
I also need to learn how to read signals. Any good signal primer websites specific to Pennsy? I found this but no pics are showing up: http://position-light.blogspot.com/2011/11/prr-main-line-survey-2009-part-7-alto.html
The others got you started...With no crossing to manage, this is a very simple interlocking - nothing more than crossovers. Twelve levers isn't much. Like Chris said, the numbers are the lever numbers in the old interlocking frame, which were doubtless transposed to the "CTC-type" switch panel when it was electrified (probably the purpose of the 1944 schematic). There is no rhyme or reason to the numbering other than their position in the original interlocking frame.5, 7, 9, 11, 13 and 15 control crossover pairs. I suspect of the 11 "spare spaces" noted in the schematic, six of those were originally for controlling points separately, one lever per pair of points since a single lever could not move two sets of points.Levers 6, 8, 10 and 12 control signals, or, rather, authorize clearance for the signal-controlled blocks, each lever controlling a pair of absolute signals. "R" and "L" is how the individual signals appear relative to the tower location. IOW, "6R" will be on the furthest track and to the operator's right as he gazes out of the tower.6L, 8L and 12R are dwarf signals, each capable of indicating "approach", "stop" and "restricting" indications. The rest are either on masts or (more likely) bridges. Notice that the dwarfs are controlling reverse movement on their respective tracks, whereas that the "traffic" levers correlate with full-height signals on Track 3, so trains normally operate in both directions on Track 3.The "traffic" levers authorize direction of movement on Track 3. The other signals are direction-agnostic, notice the "2W", "4E", etc., which are simply indicators on the panel and nothing under operator control."AP." indicates approach signals, controlled by either occupancy or the aspect of the next signal.Further interpreting the signal symbols... as an example, 12L is a full-height signal, showing a variety of indications from "clear, non-diverging" (vertical on the top head, nothing lit on the lower head) to "restricting" (horizontal on top, top-left-to-lower-right on bottom). I'm not firsthand familiar with Pennsy practice, but I interpret the "blob" at the center of each head showing that the head has a full background. This is versus, say, the signal on Track 4 at block 2427, which has no backgrounds on either head, being an approach signal only (this doesn't make sense to me, so some help from an SPF would be in order).
You'll notice that each signal has a "thick" line representing the "semaphore" position - that is the default aspect. The thin lines are the other possible aspects. For example, the approach signals at the extreme ends of the interlocking plan have "clear" as the default, since they are basically ABS (automatic block signals) indicating occupancy of the next two blocks, and not manually controlled or cleared. I'm amused that "stop" indications are horizonal-over-unlit, which is counter to Western practice, which would be red-over-red for an absolute stop.
I do not quite get the signals with the circles, or circle-with-dot, on the lower head. Again, Pennsy-specific practice, please enlighten me."DED" is "dragging equipment detector". Apparently "MG" was in charge of monitoring five of these. They would have been lights on the panel, and probably a buzzer (verses an OS bell).
SPF? Anyways are you referring to the black quarter circles that span between the red and green aspects? If so, that indicates whether or not the signal is controlled or not (whether it be by a control operator at a tower, a distpatcher, etc). Ones that are filled in are "controlled" whereas ones lacking that blob are automatic (intermediates).
Red over unlit wasn't unheard of on the western roads but it wasn't standard practice either. ... As an example UP uses a Y/Y aspect where the bottom head only has a yellow bulb and is otherwise dark if not illuminated for a Y/Y aspect.
SPF = slobbering Pennsy freak. Anyway...
D'oh! Thanks. It's been nearly four decades since I was hands-on with a schematic.Are you referring to the (now former) e/b approach signal to Walong?
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Topic: MG Interlocking- interpreting this track diagram (Read 1486 times)
