Posi Traction

Limited slip differentials use various mechanisms to allow normal differential action when going around turns. When a wheel slips, they allow more torque to be transferred to the non-slipping wheel.

PosiTraction transfers torque from the wheel that slips to the wheel that grips. Actually, both wheels turn together; it's just that one tire slips while the other one bites in.

[Positraction was an important plot element in the movie My Cousin Vinny.]

"Posi" has been an important part of American automobile folklore for decades (AmericanCulturalAssumption). Even today references to "posi" are used plentifully in hardware engineering circles. Positraction is used as a metaphor all over the place in process automation and other control applications.