Spur Gears

Spur gears or straight-cut gears are the simplest type of gear, the most common and in many cases, the most cost effective.

Spur gears are excellent at moderate speeds - up to 1200 ft per minute - but tend to be noisy at high speeds. Where noise mitigation is a factor, but higher speeds cannot be avoided, it is recommended that a nylon or non-metallic gear be used, reducing much of the noise and vibration caused by metal to metal contact. or employ helical gears.

Spur gears can be classified into two pressure angles, 20° being the current industry standard and 14½°,often found in older equipment. Spur gear teeth are manufactured in either involute or cycloidal profiles.

Spur gears are either external and internal gears. Gears with teeth cut outside of the cylinder are known as external gears. Gears with teeth cut on the internal side of the cylinder are known as internal gears. An external gear can mesh with an external gear or an internal gear.

When two external gears mesh together they rotate in the opposite directions. An internal gear can only mesh with an external gear and the gears rotate in the same direction.