Author's Homepage:   Kurt M. Marshek
Chapter 15: Spur Gears
"Gears, defined as toothed members transmitting rotary motion from one shaft to another, are among the oldest devices and inventions of man. In about 2600 B.C. the Chinese are known to have used a chariot incorporating a complex series of gears like those illustrated in Figure 15.1. Aristotle, in the fourth century B.C., wrote of gears as though they were common place. In the fifteenth century A.D., Leonardo da Vinci designed a multitude of devices incorporating many kinds of gears."