Gearbox provides speed and torque conversions from a rotating power source to another device using gear ratios.Planetary gearing is a gear system that consists of one or more outer gears, or planet gears, revolving about a central, or sun gear. Typically, the planet gears are mounted on a movable arm or carrier which itself may rotate relative to the sun gear. Planetary gearing  systems also incorporate the use of an outer ring gear or annulus, which meshes with the planet gears. The axes of all gears are usually parallel, but for special cases like pencil sharpeners they can be placed at angle, introducing elements of bevel gear.

The Planetary Gearbox arrangement is an engineering design that offers many advantages over traditional gearbox arrangements. One advantage is its unique combination of both compactness and outstanding power transmission efficiencies. A typical efficiency loss in a Planetary Gearbox arrangement is only 3% per stage. This type of efficiency ensures that a high proportion of the energy being input into the gearbox is multiplied and transmitted into torque, rather than being wasted on mechanical losses inside the gearbox.Another advantage of the planetary gearbox arrangement is load distribution. Because the load being transmitted is shared between multiple planets, torque capability is greatly increased. The more planets in the system, the greater load ability and the higher the torque density.

The Planetary Gearbox arrangement also creates greater stability and increased rotational stiffness.Planetary gearboxes, also known as epicyclic gearboxes, provide increased torque with a reduced size motor. This can be quite useful in applications that need a lot of power but do not have a lot of room available for a motor. A hybrid motor with planetary gearbox combines the accuracy of a hybrid motor with the great power-to-size ratio of planetary gearboxes, resulting in an extremely efficient motor for high performance jobs.