Adding electrical switching capability to a Tortoise
The Tortoise slow motion switch machine has been around since 1984 and has remained basically unchanged, an indication of good design. I began using them in the early 1990’s after reading an article in MR.
This article is about a modification that I made to overcome a problem that arose when using them with Shinohara code 100 points.
I’m not offering this information to deal with the problem that I had, but to suggest that my solution could be useful in a contemporary situation, because it adds extra electrical switching to the Tortoise. So before elaborating the original problem let me start with the solution. I attached micro switches to the body of the machine either end of the throw mechanism which gives you two extra switches that augments the internal switching of the Tortoise and could be useful for control panel lamps, signal circuits etc. The accompanying photograph shows the very simple installation, a small screw holds each switch in place. In the beginning I did disassemble a Tortoise to make sure that the installation wasn’t going to interfere or damage the internals. So if you need extra switching it’s a simple solution.
Only the masochists amongst you need read on. This is the background to why I started using these external switches rather than the internal ones. When I began building layouts there was only code 100 and code 70 track available and if you wanted no.8 points it meant Shinohara. I originally used Tenshodo twin-coil switch machines to throw the points, but they were designed to be surface mounted and were fairly strong in their action despite the spring that connected them to the throw bar. I did design and build a below bench mechanism, but then discovered the Tortoise and abandoned the project. (I still have them including the push buttons and a capacitor discharge unit if anyone’s interested).
The Tortoises worked beautifully and reliably, I’ve never had one fail. However when I used the internal switching to supply power to the closure rails and the frog I would often get a momentary short as the points changed. The problem is caused by two interrelated events, the very short break before make of the internal switching of the Tortoise and the piece of metal attached to the throw bar of the points that is designed to enhance electrical contact by sliding under the stock rails.
The Shinohara employee assigned the job of installing this metal strip was a heavy drinker by the name of Saki San. This could be the only reason for such sloppy workmanship, because the metal strip was seldom centred, it was always protruding further under one side of the stock rail than the other and it wasn’t consistently one side or the other. Indeed when he was sober some were actually centred. The result of Saki San’s drinking was that as the Tortoise activated the internal switching it would move to the opposite pole before the metal contact strip had cleared the stock rail, hence the short. The strip couldn’t be removed without drilling out the rivet holding the whole throw bar together, however I did manage to carefully cut parts of it away on a couple of points, but you ran the risk of altering the alignment of the closure rails. The micro switches solved the problem because they were at the end of the throw bar travel, a simple solution, problem solved.
When I built my extension a few years ago I again used code 100 on the main line for several reasons:
- I had quite a few switches and a lot of track salvaged from the hidden loop and storage tracks of the original layout.
- Code 100 is actually prototypically correct for some of the Pennsy. main lines which were upgraded with 157lb rail.
- It meant that I had continuity with the original layout.
I was still short of a few sets of points but to my surprise new ones were still available, surprising as other than Pennsy. modellers who would use code 100 these days?
Surely after twenty-five years Saki San would have had a liver problem and a sober robot would have taken over installing those metal contacts. Oh no, son of Saki San now works there and he is also a drinker, nearly all of the new points suffered the same problem and required micro switches.
I did lay my branch line with Shinohara code 83; the points are a much better design, no micro switches needed unless extra electrical switching is required. Interestingly quite a few members have run their trains on the layout and nobody has yet commented on the code 100 track, interestingly where the code 83 runs next to it the difference isn’t very obvious.
As it is unlikely that any of you will be using code 100 track I suspect that none of you will ever have to deal with the Saki family.
NOTE: When I began laying track for the extension I decided to try the Cobalt switch machines, I did so for two reasons:
- They were smaller and hence useful in a couple of tight spaces.
- I wanted to support the initiative of an Australian company.
Regrettably I installed around ten and quickly they started to fail despite applying the recommended voltage, it was a common problem, the inability of the latching component, the dreaded clunking problem. I kept sending them back ($7 a trip at the time) and each replacement eventually did the same thing. I still have three in place and one is starting to go clunky. If anyone can use some clunky Cobalts you’re welcome to them!