One of the original designs had the turntable mounted directly on top of the stepper-motor. The wagging of the turntable when it stops shows the momentum of the turntable as the motor tried to stop. Also, all the wright is on the motor bearings.
Testing the heavy-duty bearing
These "Lazy Susan" / display bearings allow the weight of the train on the turntable to be spread over the width of the turntable. The turntable is stull driven by a stepper-motor, but now using a belt drive.