External Helical Cut Gears With Internal Spur Gear Involute Splines

Transmission Gears External Spur Gear with Internal Spur Gear Involute Splines

Description of Internal Gears

Internal Gears are gear teeth generated in the internal diameter of a cylinder while external gears have

the gear teeth generated on the outside diameter of the component. While there are several different types

of gears, only two can be produced as both internal and external gears, spur and helical gears.

While internal gears are ideal for applications for high power transmission within small overall dimensions,

there are design constraints that must be addressed in order to achieve the advantages that internal gears offer.

An internal gear can also be called a ring gear. Internal gears are used in planetary gear box applications,

but can also be applied in other situations. Advantages of the use of a planetary gear train are low vibration,

high speed reduction ratio, and the low cost for the entire train layout. Since the centers of the mating wheels

can be closer than those of external gears, internal spur gears are preferred in applications where space is a constraint.

Some of the common uses for planetary gear transmissions are robotic arms, hybrid vehicle power transmissions

and turbine generators. Internal gears can also be cut in helical gears just as external gears can be cut in helical gears.

These types of internal gears can be found in some internal gear drive, simple pairs, internal differential drives and

internal planetary drives. Special housings have to be designed in order to accommodate the internal gear.