Escapement
The mechanical device in a watch or clock by which the motion of the train is controlled so that the power may be distributed uniformly. Saunier divides escapements into three principal classes: Recoil, Dead Beat and Detached. 1. Recoil escapements are so classed, because at a certain period of this action, the wheel moves backward or recoils in a manner more or less marked. The verge escapement in watches and certain forms of the anchor in clocks, may be used as examples. 2. Dead Beat escapements are so called because except during the actual impulsion, the wheel remains stationary, a point being supported either against the axis of the balance itself, or against the accessory piece, concentric with this axis, which catches it in its movement of rotation. The cylinder and duplex escapements in watches and the pin and Graham escapements in clocks are examples of this class. 3. Detached escapements may be called Dead Beat escapements, but their principal characteristic consists in the fact that the balance performs its vibration in absolute independence of the wheel, except during the very brief periods of impulse and unlocking. The wheel, then, does not rest on the axis of the balance, but on an intermediate and distinct piece. The lever escapement in watches, the detent escapement in chronometers, as well as several forms of escapements employed in clocks, come under this head. See Anchor, Chronometer, Cylinder, Dead Beat, Duplex, Graham, Pin Pallet, Pin Wheel and Verge.