Signedon lead back of pendulum bob: Simon Willard / Roxbury / Massachusetts / 1822
FunctionThis is a model that demonstrates the escapement device of certain clocks called the recoil or anchor escapement. It works by the interaction of a dented wheel with a piece called the anchor that has two arms interlocking with the wheel. In one cycle, a locked arm is pushed by the wheel (driven by the weights wound around its axis) in one direction and radially outwards, which causes the opposite arm to move inwards to eventually stop the wheel's rotation. In contrast to other escapements, the momentum on the pendulum then actually makes the wheel turn backwards until the pendulum stops. Then, the force of the wheel on the anchor makes it swing in the opposite direction completing the cycle. The speed of the oscillations is controlled by the pendulum attached to the anchor and the wheel's inertia. Each cycle gives the pendulum a push to keep swinging with the same amplitude.
Historical AttributesMade by Simon Willard for Harvard in 1822.