Super wrote
But no gears to the wheel axle? Just a friction wheel?

Correct. No slipper clutch either - the mechanical piece that clicks when the train is stuck. The slip of the roller to wheel was all that allowed for jams. Inside the drive unit is also brass/metal gears.
Super wrote
BTW Toy-Trains_Things...you are typing quite well one handed!
Iphone! You notice there are only a few links though. Links, images, etc are harder with one hand. Only 4 weeks to go. 🙁