The plastic material commonly used for making gear wheels is
(1) Polyesters
(2) Nylons
(3) Bakelit
(4) Polystyrene
Answer: (2) Popular materials for plastic gears are acetal resins such as DELRIN, Duracon M90; nylon resins such as ZYTEL, NYLATRON, MC901 and acetal copolymers such as CELCON. The physical and mechanical properties of these materials vary with regard to strength, rigidity, dimensional stability, lubrication requirements, moisture absorption, etc. A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine. Geared devices can change the speed, torque, and direction of a power source.
