Sun Planet Gear

Components of a planetary gear

Sun gear

Ring gear

Planet gear

Planetary carrier


Planetary Gears

Planetary gears are also referred to as epicyclic gear trains. They contain an input and an output shaft in a coaxial arrangement. They consist of a number of gear wheels arranged around a central gear. Since this arrangement is reminiscent of planets orbiting the sun, the central wheel is also referred to as the sun gear, while the surrounding ones are called planet gears. They are located within an external gear ring. The sun gear is driven by a motor and transmits its motion to the surrounding planet gears, which roll against the surrounding gear ring and thus orbit the sun gear evenly. The planet gears are mounted on a joint carrier that is connected to the output shaft. The rotational speed of the output is lower than that of the drive, and the torque of the output is higher in reverse proportion. The more gear wheels mesh with each other, the higher the torque. In general, one planetary gear system contains three to four planet gears.

Planetary gears commonly comprise a combination of several gear wheels toggled within and behind each other, on the basis of this simple basic form. Several simple planet gear sets can be merged into a multiple gear unit. This enables a hub gear changer in a bicycle to have in excess of the three speeds usually achieved with a simple gear set.

We are a leading specialist in the power transmission industry, please feel free to contact us regarding any planetary gearbox requirements. We have the in-house capability to adapt to all your requirements.”


Advantages of planetary gear

High efficiency

High torque transmission capacity

Compact construction

Power transmission efficiency is very good

High power density

R & D experience

Exporting country

Designed product

A Trusted Gear Transmission Company

XinLan Transmission is a manufacturer base of heavy and light duty crown wheels and pinions, transmission gears and shafts, axles, and various other products. The company has established a complete quality assurance system and passed the ISO9001 quality system to ensure the stability of product quality. The business philosophy of high quality and favorable price has helped the company win customers in more than 35 countries around the world. We are committed to providing lifelong support for your needs with the professionalism of professional technicians and a first-class after-sales culture. We offer a wide range of genuine parts at competitive prices and are available from stock. For an immediate quote, please contact us today.

Operating modes of planetary gears

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As a rule, a planetary gear comprises three shafts – the sun gear, the planet carrier, and the external ring gear. Often, though, the motion of one of the shafts is arrested, so that the input and output are on the other shafts. Which shaft or wheel is held, which serves as the input and which as the output depends on the constructive tasks. In certain cases, three-shaft operation is also used, in which either two shafts are driven and one is the driver (summation gears) or vice versa (distribution gears). Temporary three-shaft operation is also possible. Here, the third shaft is fixed by a frictional coupling. Under load, two-shaft operation can be interrupted and then restored by uncoupling and coupling.


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