Tri-star (wheel arrangement)

If either of the wheels in contact with the ground gets stuck, the whole system rotates over the obstruction.

In the original patent, the direction of the vehicle is controlled through the differential steering.

[1] Lockheed modified an M2A2 105mm Light Howitzer and produced it from 1969-1977 with a drive unit and tri-star wheel system into an Auxiliary Propelled Howitzer they termed "Terra Star."

The only surviving prototype is located at the Rock Island Arsenal Museum.

Perhaps the most famous application was the Landmaster, a unique armoured personnel carrier (APC) created as a movie prop for the 1977 film Damnation Alley.