About gears
n general, today’s engineering avoids gears wherever possible because they can be expensive to manufacture and too quiet. Materials able to transmit engine power must be highly precise in form and their material must have strength equal to the application. Gears in low-power applications such as a water-pump drive or (in the old days before all tachometers were electric) tach drives can be molded out of nylon or other plastics. Also sometimes seen are accessory gears made from brown or amber-coloured phenolic plastic. The
