USA period puzzle

[Peter Fox]

There's a picture on Shorpy (Glass-plate era US photographs for those that don't know) of some strange apparatus.
https://www.shorpy.com/node/25506 You might need to click on the pic to enlarge it to see the details.

At a first glance this looks like horseplay but then notice electricity on this backwoods RR. I'm guessing this is an 'it's perfectly safe' promotion. But what is this all about in detail? Basic facts there are conduits going to what might be an insulated joint. There's a lineside box of bits at head height. But from the picture I can't see any wires out of the box to say the lineside poles. Now look carefully at the front of the loco: There's a strange box on the buffer beam and it has springs in it - I'm guessing to contact the rail. (Shoes pun possibly.) And is that a wire (looks like a hair on negative, but rest of plate is clean.) coming out of the box up to the buffer beam? There are other asymmetries about the buffer beam.

In general this looks like some form of signalling being tried out on a backwater by Messrs Heath and Robinson. Does it ring a bell on the loco? Does the loco supply 12 volts through the shoe? I feel sure this isn't a track circuit in the way we'd use it today. ie. being connected to a signal panel. Perhaps if the section ahead is occupied it rings a bell in the cab?

 

[edwin_m]

There is a cable from the lineside cabinet going down by the standing man's right leg, which may continue through the conduit to the track.

Coded track circuits have been around since the 1920s at least so could contemporary with this type of locomotive. It could be some kind of trial using an old loco and a remote branch line, before wider application.
https://en.wikipedia.org/wiki/Pulse_code_cab_signaling

Pulse code cab signaling is a form of cab signaling technology developed in the United States by the Union Switch and Signal corporation for the Pennsylvania Railroad in the 1920s. The 4-aspect system widely adopted by the PRR and its successor railroads has become the dominant railroad cab signaling system in North America with versions of the technology also being adopted in Europe and rapid transit systems.

 

[MarkyT]

The failsafe track circuit was invented in the USA in 1872 by William Robinson. I don't know whether a Mr Heath was also involved
From Wikipedia: https://en.wikipedia.org/wiki/Track_circuit

Robinson first demonstrated a fully automatic railway signalling system in model form in 1870. A full-sized version was subsequently installed on the Philadelphia and Erie Railroad at Ludlow, Pennsylvania (aka Kinzua, PA), where it proved to be practical. His design consisted of electrically operated discs located atop small trackside signal huts, and was based on an open track circuit. When no train was within the block no power was applied to the signal, indicating a clear track. An inherent weakness of this arrangement was that it could fail in an unsafe state. For example, a broken wire in the track circuit would falsely indicate that no train was in the block, even if one was. Recognizing this, Robinson devised the closed loop track circuit described above, and in 1872, installed it in place of the previous circuit. The result was a fully automatic, failsafe signalling system that was the prototype for subsequent development.

If this was a feed location for the two track circuits arranged either side of the single rail block joint, then there need not be any connection to other circuits. The relays, and connections to other circuits, would be at the other respective ends of the sections, linked only by the rails. Early track circuits were usually battery powered so the trackside box probably only contains some primary cells that would have to be changed by technicians periodically. Style of clothing and the locomotive suggests a date later than the 1870s so probably not Mr Robinson himself.