Planetary gearbox: cost-effective and power saving solution

February 12, 2015 12:59 pm

 In today’s competitive world planetary gearing is becoming more popular, cost and power saving gearings and used in a wide range of applications as alternative to other type of gearboxes.
IntroductionEpicyclic gearing or planetary gearing is a gear system consisting 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. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes with the planet gears. Planetary gears (or epicyclic gears) are typically classified as simple and compound planetary gears.
Simple planetary gears have one sun, one ring, one carrier, and one planet set. Compound planetary gears involve one or more of the following three types of structures: meshed-planet (there are at least two more planets in mesh with each other in each planet train), stepped-planet (there exists a shaft connection between two planets in each planet train), and multi-stage structures (the system contains two or more planet sets). Compared to simple planetary gears, compound planetary gears have the advantages of larger reduction ratio, higher torque-to-weight ratio, and more flexible configurations.
The axes of all gears are usually parallel, but for special cases like pencil sharpeners they can be placed at an angle, introducing elements of bevel gear. Further, the sun, planet carrier and annulus axes are usually coaxial.
RatioOne of the planetary gearsets from its transmission has a ring gear with 72 teeth and a sun gear with 30 teeth. Lots of different gear ratios can be obtained out of this gear set, assures the company.
Why planetary?The efficiency loss in a planetary gear train is 3 per cent per stage. This type of efficiency ensures that a high proportion of the energy being input is transmitted through the gearbox, rather than being wasted on mechanical losses inside the gearbox.

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