I know they had their own call box system from 1922 through the late 1940's -- in what were the Lincoln, West and South Park Districts before consolidation. The boxes were different from the Chicago Department of Electricity Fire Alarm and Police Call Boxes used throughout the City. So maybe they had their own signals too.
Here is some eye candy -- with more parts pictures to come --
I need to find out what kept the porthole lens doors closed. There are 2 -- 3/8" threaded holes for each lens porthole door -- and no hardware to fill them.
The silvered glass reflectors are all there -- and seem to be harnessed together. They have "ears" on them so they attach with 2 #10-32 screws (top and bottom) to the inside of the main solid body housing.
Only the lenses are held in the cast aluminum porthole lens doors (with cast aluminum visors) -- which hinge on the right side, as you are looking at them. The lenses are held in by a wire lens retainer that seems odd to me. The basic C-Shaped wire retainer has 4 smaller semi-circular bends in it, that fit into slots 90 degrees apart on the inside of the lens portholes.
The porthole lens doors have raised areas on their faces that correspond to the 2 threaded 3/8" holes. I think some kind of winged thumb screws -- with L-Shaped hold downs were used.
I went through a lot of pictures Sunday, and I think this signal is either a Tokheim (or an ESSCO) because in a lot of posts, it seems collectors get signals from those two brands confused. But since it's from Chicago, being an ESSCO also seems like a possible option.
I did find a picture of a Tokheim signal that shows closures that seem to fit the bill. Interestingly, they are mounted at the 10 o'clock and 4 o'clock position on the porthole lens doors. On my signal, the mounting holes are at the 2 o'clock and 8 o'clock positions instead.
On the picture of the Tokheim signal -- it seems that both sets of closure positions are possible. I think the 2 o'clock and 8 o'clock positions were used on mine, because the cast aluminum visors only have 2 mounting points -- and one of them would interfere with the 10 o'clock closure position. The Tokheim looks like it had sheet metal visors with 3 mounting points. The porthole castings on mine do not have the raised spots at the 10 and 4 o'clock positions.
I apologize for what must seem like incoherent babbling. I'm hoping someone out there might recognize the signal that I'm talking about, and maybe have a picture or 2 to help me identify it.
Thanks in advance. Here's an image showing the closure parts on the Tokiem signal, that I think would be compatible with the signal I have. My thanks to the collector here that I swiped it from.
Here's an image showing similar closure parts from Larry's restoration thread.
that and be there on time, seems some odd hours to me 
