ˈcrown-wheel
a. 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. |
b. spec. In the gears of motor vehicles.
| 1908 Westm. Gaz. 29 Dec. 4/1 The transmission [of a motor-car] being by chain,..crown-wheel, and differential gears. 1926 Amer. Speech I. 686/2 Automobile nomenclature... American: ring gear... English: crown wheel. 1963 R. F. Webb Motorists' Dict. 70 Crown-wheel, the largest bevel gear in the differential..housing. |