NOT Gate

A NOT Gate is a mechanical block that will invert the gear input given to it

Breaking
A NOT Gate can be mined with any tool or by hand.

Mechanical component
A NOT Gate will invert the input given to it.

If there is a powered gear on the input end of the block then the gear on the output end of the block will not be powered by the NOT Gate and if the input gear is not powered then the output gear will be powered.