Not quite sure how it works, but it is a series parallel circuit. What you observed is what needs to happen when you turn the steering wheel while standing still on an articulated unit. The inside tires roll towards each other while the outside wheels roll away from each other, yet when you step on the go pedal, all the wheel turn in the same direction, but the inside wheels turn slower than the outside wheels. To top that off, you can turn the steering wheel left, right, left, right while traveling forward or backwards or stopped and the circuit adjusts constantly AND NO TURF SCUFFING EVER OCCURS!!! Simply ingenious, to me at least! /forums/images/graemlins/wink.gif
I wonder who figured it out?