Nostalgia & History > What is this?

I found this picture on the Digital Library of America. 
 
Title: Railroad equipment. Creator: Nollau, Louis Edward, 1883-1955.  Format:images.  Date uploaded: 2012. Publisher: University of Kentucky. Type:image.  Accession number: 1998ua002. Source:Louis Edward Nollau Nitrate Photographic Print. 
 

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Looks a lot like a cab signal/automatic train stop pick-up shoe. Note the serrated mounting bracket so that the height can be carefully adjusted for specific clearance above the transmitting united mounted at track side.

Thanks HotWater. 

https://en.wikipedia.org/wiki/Intermittent_inductive_automatic_train_stop

My first thought is that this is a hot box detector.  The adjustable height thing elevates the sensor to the correct height.  I would further guess that the sensor itself is some kind of temperature sensing device.  These days, though, it's more likely an infrared 'heat detector'.  

However, I'm really puzzled with what must be an optical illusion.  In particular, the casting is mounted to the ties, and the adjustable-height sensor is attached to it.  But the hose (electric cable?) is attached to what looks like the a junction box (maybe a pneumatic sensor?) mounted on the frame of the locomotive.  Perhaps this is teaching tool?
 

Not so much a "pickup shoe" as an "inductive receiver"

It looks like it's not really attached to the ties, as if you look closely it looks "floating" above them.

I agree. To me, it looks like some semi-permanent setup, like house power.

Note that that's an Arch Bar truck, too.

Brian Ehni

On second thought, that thing is hanging off the END of the truck, between two steel plates.

Brian Ehni