nagle@well.sf.ca.us (John Nagle) (12/21/90)
The Milton Bradley Big Trak toy, a microprocessor-controlled tracked vehicle, had a mechanical clutch so arranged that if both tracks were running at roughly the same speed, they would be locked together, thus producing straight-line travel. Perhaps you can find one of those units. John Nagle
nagle@well.sf.ca.us (John Nagle) (12/21/90)
"Dual Drive, Dual Control Robot Motor", Edmund Scientific part A31,827. Was $4.95 each in catalog 8747 (1987). Contains two 6VDC 150mA motors in a single housing with a magnetic differential coupling. Edmund Scientific is at 1-609-573-6250. John Nagle