A clock movement refers to the mechanism that causes the clock to work so it will indicate time. All clocks require some form of movement to function as a timepiece. In most instances, the clock movement has a dedicated function for enabling the clock to tell time; however, there is one category of movement that also powers additional clock functions.
Mechanical clocks have a movement that relies on a spring or a weight to make the clock work. Mechanical clock movements include such parts as an escapement or anchoring device that regulates movement, gears, the setting mechanism and weights. Mechanical clock movement types include a verge-and-foliot escapement type that uses a shaft-and-wheel mechanism and that came into use around the 14th century; and spring-powered clocks that appeared in the 16th century.
Pendulum movements involve a cord that suspends a weight, or pendulum; and came into use during the 17th century. The clock owner winds the clock by pulling the cord to lift the weight. Because pendulum clocks could run on a single "winding" for a much longer interval than a clock with a mechanical movement, householders often preferred clocks with pendulum movements.
Perhaps the most common modern clock movement is that of the quartz clock movement, found in many types of modern clocks ranging from the simple alarm clock to fancy cuckoo clocks. A quartz crystal vibrates in response to an electrical current, which enables a quartz clock movement to emit a signal that powers the clock's timing mechanism.
Many modern clock movements get their power from a battery, which acts as the power source to enable the time-telling movement, such as quartz. Some modern clocks that have some pendulum action but have had quartz-movement adaptations added to boost function use batteries as a power source.
A special category of clock movement involves animated movements. Primarily, you find this type of combination movement in cuckoo clocks. Modern cuckoo clocks involve a clock and figurines of a cuckoo and sometimes other animated figures, all powered by a battery-supported quartz movement. The more figurines a particular clock has, the more quickly it will exhaust the battery or batteries that power it. Simpler animated clocks with fewer figures can operate on the same battery for about a year when the batteries are completely new at installation.