Columbia Encyclopedia

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wheel

(Encyclopedia)wheel. Through the many millennia of the Paleolithic period and the Neolithic period no use of the wheel was known to humans. Its use was not known to the Native Americans until the Europeans introduc...

Ferris wheel

(Encyclopedia)Ferris wheel, amusement park ride. It consists of a power-operated wheel that is about 50 ft (15 m) in diameter. It has two rims that are parallel to and equidistant from the shaft about which the whe...

wheel bug

(Encyclopedia)wheel bug: see assassin bug.

wheel window

(Encyclopedia)wheel window: see rose window.

water wheel, device

(Encyclopedia)water wheel, device for utilizing the power of flowing or falling water. The Norse wheel is the oldest type known. Despite its name it probably originated in the Middle East, where the swift stream re...

wheel and axle

(Encyclopedia)CE5 Wheel and axle wheel and axle, simple machine consisting of a wheel mounted rigidly upon an axle or drum of smaller diameter, the wheel and the axle having the same axis. It is fundamentally a...

ratchet and pawl

(Encyclopedia)ratchet and pawl, mechanical device that permits motion in one direction only. The ratchet is usually a wheel with slanting teeth. The pawl is a lever tangential to the wheel with one end resting on t...

differential

(Encyclopedia)differential, in the automobile, a set of gears used on the driving (usually rear) axle. The two wheels on the driving axle must be interconnected in order to receive their energy from the same source...

grinding

(Encyclopedia)grinding, process by which surface material is removed from an object, usually metal, by the abrasive action of a rotating wheel or a moving belt that contains abrasive grains. A grinding wheel can be...

steering system

(Encyclopedia)steering system, in automobiles, steering wheel, gears, linkages, and other components used to control the direction of a vehicle's motion. Because of friction between the front tires and the road, es...