Ertl Ford 7710 Tractor

[sparkycuda]

To make an "electrical differential", wire the two motors in series. When one wheel senses a heavier load (usually the inside wheel when turning) the other wheel will speed up. Of course, you have to use different voltage motors than normal - ex: if 12V battery, then each motor should be rated at 6V.
This method is used in some model wheel loaders that have 4 wheel motors. Motors on each axle are in series, while the front & rear axles are wired in parallel.

Ken