Internal gear is an opposite of external gear, internal gear is having teeth on the inner edges. Internal gears providing compact parallel shaft transmission drive with large speed reduction. Internal gear can also work with two or more external gears. Internal gears are cost effective gears, teeth are cut into the inner diameter while the outer diameter is smooth.

Internal gears are available in brass only, these gears perform low sliding and high strain loading. Internal gears used in rollers and heavy duty industrial applications.