Relays for train separation

Classic Toy Trains Forum
1

I was reading a back issue of MR this morning. The Santa Fe actually paid to get the Museum of Science and Industry train layout in Chicago build, back in the 1950s.

One of the devices was a humongous relay machine that allowed automatic, multiple train usage on the same track (broken into blocks).

If a train got too close to another train, the relays would gently slow it down by kicking in a progressive series of resistors that lowered the current to the overtaking locomotive.

Pretty nifty stuff. Relays also can control other functions as well, as they are really switches that control switches. I haven’t yet used them but I plan to incorporate them in my layout.

dave v

2

Dave,

What is your timetable for wiring and relays?

I am working on some train control products for Three-Rail Innovations that will make the job a lot easier.

John Kerklo
TCA 94-38455
www.Three-Rail.com

3

I have been using relays for ove 15 years, they can do some relly cool stuff. I use DC relays and a seperate DC power supply with one side tied to the track ground. I have an electronic delay circuit, that has a variable timer on it. When set to low it prevents chatter, and when set longer it can be used for other things.

The 3 terminals are DC +, DC -, and a trigger from the track ground.
Below is a grouping of 8 of these relays, configured to control a a loop of track with a 4 track yard. I called this thing THE BRAIN.

click to enlarge

4

Dave, right before they took the old layout down, I visited it - when they were running only one train and it all looked pretty beat upThe relay box had a glass door where you can watch the relays thump as the train went along - as you said, they controlled the switches and some accessories as well. Here’s a link to the current MSI layout: http://www.msichicago.org/exhibit/great_train_story/index.html

5

Here is a ‘history’ of the layout: http://www.msichicago.org/exhibit/great_train_story/history/history_01.html

6

For some heavy-duty relay operation, see http://tmrc.mit.edu/history/

7

John,

The upper shelf layout I’m concentrating on for the remainder of this year. It is single-tracked, operating on DCS.

I likely will go double-track for the lower layout (connected to upper via a helix). Later on, I will be thinking about ways in which I can enhance operations using relays, most likely with signals, possibly in collision avoidance. A bit down the road.

I think that an article on using relays in combination with signals and other things would be good in one of our toy train mags.

dav