The LT230T transfer box's centre differential is there to allow the propshafts to turn at different speeds when cornering to stop drivetrain wind up. The speed difference is quite small and the centre diff gears are only designed to cope with these low speeds.
If you are driving on snow or ice and you get wheel-spin from one front wheel, the rear propshaft will not be moving, and the front will be going at double speed. This means the small centre diff gears will be spinning too fast and after a matter of only a few seconds the planet gears might friction weld to the cross pins causing the gears to fail. Of course in this situation the centre diff should be locked to avoid failure.
But there are instances when it's not convenient to keep the diff locked or to constantly lock and unlock the diff as the available traction dictates, like when driving fast on a low traction surface, the vehicle will not handle well when locked but is likely to wheel spin when unlocked.
In these situations the Ashcroft Automatic Torque Biasing Centre Differential will limit the amount the difference in propshaft speed and transfer torque to the axle with traction. The two big advantages are increased traction when unlocked and eliminating the weakness of the stock unlocked centre diff.