Engineering
Open diff makes torque equal. But that's almost zero because the wheel in the air cannot transmit any torque so the other wheel will also get zero, and the car will stop.
But if the wheel in the air is stopped there is a lot of torque, the other will get half of the torque the engine provides (multiplied with gear ratio and axle ratio) but with double the speed.
So this is possible with handbrake only on the wheel in the air, is easy to adjust brake shoes lose on the other wheel, or disconnect the cable.
- or locked rear diff with no axle on left side