Clockwork

Clockwork means the inner workings of mechanical machines clocks (where it is also called a "movement". Also other similar mechanisms with a complex series of gears.
A clockwork mechanism usually has a clockwork motor. This has a mainspring, a spiral of metal ribbon. Energy is stored in the mainspring by "winding it up", turning a key attached to a ratchet which twists the mainspring tighter. Then the force of the mainspring turns the clockwork gears, until the stored energy is used up. The adjectives "wind-up" and "spring-powered" refer to mainspring-powered clockwork devices. These include clocks and watches, kitchen timers, music boxes, and wind-up toys.