Back in the late fifties, early sixties there was a train controller marketed as the "rollacontrola' which used a mechanical drive to feed pulses of 12 volt power to your model railway. I saw it demonstrated at Westminster Hall at the then Easter Model Railway Exhibition. As it was a school trip, which included a visit to the Science Museum and the Natural History Museum, we ended up at the MRE late in the afternoon, but we saw Frank Dyers 'Borchester Town' and other layouts but it was the trade stands which held my fascination. Never before had I seen such a cornucopia of Model kits, bits and handbuilt loco's and coaches on sale, I spent a long time athe EAMES stand and K&C Keyser (K's) and spoke at length with Bob Wills of Wills Finecast (now South Eastern Finecast). But it was the trade stands like H&M, Welkut, and Kings Cross Models where you could the electrical bits and pieces, and a demonstration of the 'Rollacontrolla' (I'm not sure of the actual spelling but I seem to recall it was a part of the Rolls Razor Group - someone correct me if I am wrong)
After seeing the RC demonstrated, our science teacher, the legendary Tom Marshall of The Grove School St. Leonards, set out to design and build a replica of the controller we had seen, I know it had a synchronous motor out of a fan, with the autual moving parts machined from copper rod which was held together with the then new "Araldite'. Several prototypes were produced as projects by the School Radio Club and were tried with some success on a hastily constructed School Model Railway. the unit was powered from the science laboratory's low voltage ring main which was on every bench and could be set by us lab stewards to any combination of voltage and amperage required for experiments - we had long since passed on from dry cells at that time.
The construction of the RC meant that the actual handle was' live' to the operator which was OK for 12 volts but someone had tweaked the power up and when we came to run the railway at lunchtime, the first operator got a very big shock and the Triang Jinty we were using had terminal melt down in the motor, this resulted in all further experiments being banned unless they were teacher supervised. Anyway at that time we had progressed on to the building a prototype radar unit which used magnetrons and was in a whole different league from model railways.
I'm sure if you googled Rollacontroller you might get a hit or several.
Cheers