There were two basic systems available when the first towers were built in Texas in the early 1900s. The armstrong type which was totally mechanical and the electro mechanical shown here. Because the commercial power grid was unreliable, they used wet cell batteries to power the plant. Large glass jars were filled with caustic soda and water. At the bottom was a zinc crows foot electrode and a copper strip was hung on the side. A number of these were hooked up in series to get 110volts DC. This powered coils in the interlocker cabinet, lights, semaphore signals and switch motors. We now have everything hooked up to DC power supply instead but when you pull a lever the lights on the track plan panel change and the semaphores outside change aspect. It still all works after over 100 years of operation.
I liked the electro-mechanical type. The hiss of air, as a lever was thrown. An air compressor kicking on down below. I was able to get a commercial audio tape years ago, which has such sounds. Neat! Boxcab E50
This one did not use any compressed air, just solenoids, relays and motors. At one time there were two armstrong levers in Tower 17 that operated the train order boards right next to the tower. Before we moved the tower we found a bunch of abandoned linkage down in a pit under the concrete foundation and holes in the ceiling where the rods went up to the next floor. When we removed the linoleum from the floor upstairs to expose the old wood floor we found where they had been bolted down over the holes.
Yes. Electro-mechanical. Those levers are look the same as those I remember in the UP/Milw tower at Black River, WA. Boxcab E50
