Sometimes you want to be able to temporarily lock an axle from rotating.
I guess this problem can be solved in a thousand ways. In this particular case I needed a remote controlled lock mechanism that could handle heavy torque and also would be able to unlock the axle even if the axle is still under heavy torque. Preferably I wanted the mechanism to be controlled by a micromotor.
Below is my solution. The dark grey gear is permanently fixed. In the picture above, with the worm gear in the rightmost position, the green axle can rotate freely.
As soon as you turn the micromotor the worm gear moves to the left locking the green axle.