A weight-driven movement is a clock mechanism powered by the slow descent of a weight hanging from a cord, chain or gut line wound around a barrel. Gravity provides a steady, consistent force, making weights the oldest and most reliable source of power for mechanical clocks.
The earliest mechanical clocks of medieval Europe, including great turret clocks, were weight-driven, and the principle continued in English lantern clocks of the seventeenth century, longcase clocks, Vienna regulators, Black Forest clocks and many wall clocks. Thirty-hour movements were typically wound by pulling a rope or chain, while eight-day movements were wound with a key through holes in the dial. Because the force remains constant as the weight falls, there is no need for the fusee required by many spring-driven clocks. Precision regulators used weight-driven movements for this reason. When buying, collectors check that the weights, pulleys and lines are present and correct for the clock, since replacements are common. The movement should match the dial and case, and signs of marriage, such as filled holes on the seatboard, should be examined carefully.
