what sort of dc motors are in the taits and doggies at dvr?
Doggies have different motors to the Taits at DVR. The Doggies have so much resistance on them they are almost impossible to push. I know the taits use AC motors, not sure about the Doggies.
I'm sure the Taits have a permant magnet DC motor. The Doggies have the same mtors S301/X44/T320/8792/900/700 have - a older rewround Dodge starter motor. I just don't know enough about them.
Paul Gillard does lurk here as a guest, perhaps we can convince him to sign up then answer your questions ( Paul ? )
As to a 7 1/4 inch X-Trapolis (6 cars) - Wow! Rememeber the best advise,
make the body to scale and you will end up with a good unit. An out of proportion model will be jarring to you. Also consider making it compatible
electronically & scale wise with theTaits/Harris motor - Building a 6 car set will take time - and thus you will be able to MU at times.....as you build them.
Big Project there guys, but it can be done. As someone has in their user name - it 'll Rock !