Gear Ratio

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gear ratio

[′gir ‚rā·shō]
(mechanical engineering)
The ratio of the angular speed of the driving member of a gear train or similar mechanism to that of the driven member; specifically, the number of revolutions made by the engine per revolution of the rear wheels of an automobile.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Gear Ratio


(1) In a gear drive, the ratio of the number of teeth of a pinion to the number of teeth of a gear, u = z2/z1.

(2) In a worm gear, the ratio of the number of teeth of a worm wheel to the number of threads of a worm.

(3) In a chain drive, the ratio of the number of teeth of the larger sprocket to the number of teeth of the smaller one.

(4) In a belt drive or nonregulated friction drive, the ratio of the diameter of the larger pulley or roller to the diameter of the smaller.

The gear ratio is also used in the design of multiple reduction gears. In contrast to the transmission ratio, the gear ration is always greater than or equal to 1.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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