sun planet gear

Ever-Power new planetary reducers hire a floating sun equipment rather than a fixed position one.
The saying ”There’s nothing new beneath the sun’ certainly applies to planetary reducers. And, while floating sun gears have already been around a long time, some engineers might not be aware of the huge benefits this unusual gear design can offer.
Traditionally, planetary reducers possess used a set sun gear, where in fact the centre gear is attached to or machined in to the shaft. When this fixed sun equipment revolves, it turns the planet gears to create motion and/or power. Ever-Power new planetary reducers, however, are employing a floating sun gear rather than a set position sun gear.
Why a floating sunlight gear? ‘In the planetary concept, the sun is the driver, or pinion, in the apparatus set,’Ever-Power style engineer Scott Hulstein said. ‘Because the sun gear is in continuous connection with the planets, it’s important that it is flawlessly centred among the three planets in order to provide equal load posting among itself and all three planets.’
Because of normal manufacturing tolerances nevertheless, a sun equipment which is securely set upon a shaft will intermittently have significantly more load using one planet gear than on another equipment Hulstein explained. ‘By enabling the sun equipment to float, it centres itself among the three planets and creates continuous, equal load sharing.’
Equal load posting is just one of the advantages of this design. The floating sun gear provides ‘true involute actions,’ according to Hulstein. Accurate involute action occurs when the rolling sun planet gear movement between your mating gears is as complete as possible. The advantage of this comprehensive meshing of gears can be longer reducer existence, since less internal gear slippage means fewer broken gear teeth.
That does mean lower noise levels. When the sun gear is allowed to completely roll in to the world gears, there’s less ‘rattling’ as one’s teeth mesh. In place, the Ever-Power product provides ‘designed out’ the gear mesh noise by allowing the sun gear to float into place.
So why use a fixed sun gear at almost all? ‘Fixed sun gears tend to be used in accurate servo applications,’ Greg Pennings, Ever-Power Consumer Advocate, explained. ‘A fixed sun gear is necessary when precise positioning and low backlash are an integral part of the program.’ Ever-Power engineers, however, were less worried about low backlash and more interested with higher torque and/or lower noise applications.
Our planetary reducers with floating sun gears were made to contend with parallel shaft reducers, where backlash was less critical,’ Pennings said.
Utilizing the floating sun gear concept, the Ever-Power planetary reducers are able to exceed the torque ratings of similar sized and larger sized parallel shaft reducers, and yet maintain a lesser noise levels.
Sun, Ring and Planet
The most basic kind of planetary gearset is proven in the figures above. The figure at remaining shows a three-dimensional view as the figure at right provides a cross-section. In this geartrain, inputs and output can be taken from the carrier, ring and sun gears, and just the planet experiences epicyclic motion. This is the most common type of planetary gearset (with the exception of the differential) and it finds application in velocity reducers and automated transmissions. If you take apart a cordless drill, you will most probably find this kind of planetary gearset right behind the drill chuck.
Two Suns – Two Planets gearset
Cross-sectional view
Two Suns, Two Planets
The gearset demonstrated above has two sunlight gears, and the two planet gears (the yellow gears) rotate as an individual unit. The sun gears (green and dark brown) can rotate independently of 1 another. The inputs and output can be selected from either sun gear and/or the carrier. Very high speed reductions can be achieved with this unit, but it can have problems with low efficiency if not designed correctly.
Reddish colored sun input – purple sun fixed
Purple sun input – crimson sun fixed
The animations above show the ‘two suns – two planets’ gearset with one sunlight as input and the other sunlight fixed. Remember that the carrier rotates clockwise in the animation at still left and counterclockwise in the computer animation at right – even though the sun rotates counterclockwise in both situations.
The Differential
The gearset demonstrated above differs from the preceding gearsets in that it is made up of miter gears instead of spur (or helical) gears. The ‘sun’ gears are the ones that do not go through the epicyclic motion experienced by the planet. And the differential can be used to measure the difference in acceleration between two shafts for the intended purpose of synchronization. In addition, the differential is often used in auto drive trains to overcome the difference in wheel speed when a car goes around a corner.