Differential steering

A subsequent disadvantage is that changes in rolling resistance or traction from one side to the other automatically causes the vehicle to steer unless counteracted by the driver.

In controlled-differential steering, pinions within the differential are locked causing one side to rotate faster than the other.

This method was developed by the Cleveland Tractor Company in 1921 and called the Cletrac Regenerative Steering System.

The main disadvantage to this system is that it doubles the size and weight of the total transmission and therefore it has only been implemented experimentally.

[1] In the Maybach double-differential, power is transmitted through a single main transmission and then through an epicycle gear final drive on each side.

In this design, however, the average drive speed of the tracks is maintained by adding an idler to apply the opposite torque to the epicycle gear on other side of the turn.

The additional complexity in the mechanical systems and driving controls means that this capability is rarely implemented.

Depending on implementation, friction between drive mechanism and ground, and available power, a vehicle with differential steering may have a zero turning radius or a curb-to-curb turning circle equal to the length of the vehicle by driving each side at the same speed but in opposite directions.

Vehicles with long continuous tracks on each side which must slide on the ground in order to turn at all require more power.