The balance- or escape-wheel of a vertical watch, the pinion of which is driven by the contrate wheel; but the name is now commonly applied to any wheel with cogs or teeth set at right angles to its plane, i.e., a CONTRATE wheel.
1647. J. Carter, Nail & Wheel, 84. The ballance of the watch … never stirres, but when the crown-wheele, … makes it go.
1696. W. Derham, Artif. Clockmaker, 5. The Contrate-Wheel is that Wheel in Pocket-Watches which is next to the Crown-Wheel, whose Teeth and Hoop lye contrary to those of other Wheels.
1727–52. Chambers, Cycl., s.v. Watch-work, The crown-wheel, in pocket-pieces, and swing-wheel in pendulums, serving to drive the balance or pendulum.
1807. Vancouver, Agric. Devon (1813), 130. Perpendicular shaft … [with] crown-wheel of two-inch plank, with six cast iron segments, composing a crown-wheel of 108 cogs.
1829. Nat. Philos., I. Mechanics, II. vii. 30 (U.K.S.). If the teeth be parallel to the axis of the wheel, and therefore perpendicular to its plane, it is called a crown-wheel.
1884. F. J. Britten, Watch & Clockm., 68. The few verge trains with crown wheel of nine have escape pinions of six.
