Spur gears are the most easily visualized common gears that transmit motion between two parallel shafts. Spur gears are used in mechanical applications to increase or decrease the speed of a device or multiply torque by transmitting motion and power from one shaft to another through a series of mated gears. Generally speaking, when two spur gears are in mesh, the gear with more teeth is called the “gear” and the one with the smaller number of teeth is called the “pinion”. These gears can be made to a high degree of precision. Spur gears are excellent at moderate speeds but tend to be noisy at high speeds.