MechAlive

Mechalive is a function of the Revenge of the Fallen toys that allows pieces in them to move in robot mode when you perform a certain function. The gimmick is akin to Automorph Technology due to it's use of gears to create a more movie-like appearance. Some toys possess gears and bits that move when you tiwst another part or move another part. Starscream's ROTF toy has a function where moving his head causes internal gears to move in robot mode. Demolishor's toy has a gimmick where moving the elbow causes his upper arm gears to twist and turn.

Fiction
The storyline reason behind this Gimmick, since  many  gimmicks  need  one, is that the technology was developed by Autobot scientists and was stolen by Decepticon spies later. It is a powerful advance in Cybertronian battlefield technology, since it animates armor to let it deflect attacks, reinforces a Transformer's internal gearing, gives better aim, and allows for more powerful attacks.