echappement An escapement controls the movement of a gear in equal time intervals. A fluctuating anchor, a kind of hanging, inverted T with claws, allows one movement per tooth. A hook holds a tooth, the other one is then driven again by an another tooth. Thus, the anchor stays moving back and forth.

In his astronomical clock Soo Sung built around 1,000 BC a water wheel with basins (a kind of ladles) at the end of each spoke, one by one to be filled and then continue through the water weight hinging and deflating. He designed in his water clock one of the very first escapements.
Without escapement the movement gets no regularity, and drive for evenly running time is not possible. The escapement ensures that the actuator is dosed.