I would like to make a slight correction to the terminology.
Regenerative turning is a broad term that refers to "a state in which no additional energy is required from the engine to generate the speed difference between the left and right tracks necessary for turning a tracked vehicle.‘’ This term only relates to energy efficiency and does not directly affect the turning speed of a tank.
A steering system that is often discussed in the community, where one track decelerates while the other accelerates, is correctly described as a differential steering system. A differential steering system theoretically maintains the same vehicle speed when going straight and when turning, minimizing deceleration when turning.
Note that even though a differential steering device is used, the extent to which it can create regenerative turning conditions depends on the mechanism of the device.
For example, the M4 Sherman is equipped with a differential steering system, but it only enters regenerative turning when turning at the minimum turning radius.
In addition, the Leopard 1 and Centurion are also differential steering devices, but they enter a regenerative turning state only when executing a certain preset turning radius, and at other turning radii, they enter a non-regenerative turning state, wasting some of their energy.
Modern vehicles, such as the Leopard 2 and Abrams, are regenerated in all turning radii.
In fact, even with the current “clutch and brake steering” of WT, a pivot turn with one track completely fixed is theoretically a regenerative turning state. At this time, the only thing that fixes the track is the crew’s muscular strength, and no additional load is required on the engine.
When turning with a radius larger than a pivot turn, the brakes slip and require additional load, resulting in a non-regenerative state.