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WHAT IS A PLANETARY GEARBOX?
A planetary gearbox is a gearbox with the input shaft and the output shaft aligned. A planetary gearbox is used to transfer the largest torque in the most compact form (known as torque density). For a three-speed hub, a one-stage planetary gear system is used, for a five-speed hub a 2-stage. Each planet gear system has a reduction state, a direct coupling and an acceleration mode.
In mathematical terms, the smallest reduction ratio is 3: 1, the largest is 10: 1. At a ratio of less than 3, the sun gear becomes too big against the planet gears. At a ratio greater than 10 the sun wheel becomes too small and the torque will drop. The ratios are usually absolute i.e. an integer number.
About Planetary Gearbox
GREASE OR OIL AS LUBRICANT
Even with how precisely the planetary gearbox is manufactured and assembled, there are always rolling or sliding surfaces inside. That’s why each gearbox contains a lubricant – whether it’s oil, grease or a synthetic gel – to ensure the gears function well and prevent wear. In addition, the lubricant often also provides cooling and reduces noise or vibration.
WHERE IS THE PLANETARY GEARBOX USUALLY USED
- In a robot to increase the torque
- In a printing press to reduce the speed of the rollers
- For precise positioning
- In a packaging machine for a reproducible products
WHAT SHOULD YOU PAY ATTENTION TO
First of all, the primary specifications (eg.: torque, backlash, ratio) must be correct, but then the secondary (eg.: corrosion resistance, noise level, construction) and the tertiary (eg.: delivery time, price, global availability, service) are important.
Industries Using Planetary Gears:
Generally, planetary gears are used as speed reducers. They are used to slow down motors and increase the torque. Torque is the working power of the machine.
- Hoists and Cranes
- Medical Applications
WHY IS IT NAMED A PLANETARY GEARBOX?
The planetary gearbox got its name because of how the different gears move together. In a planetary gearbox we see a sun (solar) gear, satellite (ring) gear and two or more planet gears. Normally, the sun-gear is driven and thus move the planet gears locked in the planet carrier and form the output shaft. The satellite gears have a fixed position in relation to the outside world. This looks similar to our planetary solar system and that is where the name comes from.
What helped was that ancient gear constructions were used extensively in astrology for mapping and following our celestial bodies. So it was not such a big step to make.In practice, we often speak from the perspective of the use of planetary gearboxes for industrial automation. That is why we call the sun-gear the input shaft, the planet gears and carrier the output shaft and the satellite gear (or ring gear) the housing.
ARGUMENTS FOR A PLANETARY GEARBOX IN COMBINATION WITH A SERVO MOTOR
- The torque is divided over 3 gears (the planet gears), and therefore – at equal dimensions – the torque is almost 3-fold than a “normal” gearbox.
- Low backlash.
- Compact and therefore a low mass inertia.
- High efficiency.
- Closed system.
- Absolute ratios between 3: 1 and 10: 1 per stage.
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WHY CHOOSE US
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