Ever-Power new planetary reducers hire a floating sun gear rather than a set position one.
The word ”There’s nothing new under the sun’ certainly applies to planetary reducers. And, while floating sun gears have already been around quite a while, some engineers might not end up being aware of the huge benefits this unusual gear style can offer.
Traditionally, planetary reducers have used a set sun gear, where the centre gear is attached to or machined into the shaft. When this set sun equipment revolves, it turns the earth gears to create movement and/or power. Ever-Power new planetary reducers, however, are employing a floating sun gear rather than a fixed position sun gear.
Why a floating sun equipment? ‘In the planetary idea, 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’s flawlessly centred among the three planets to be able to provide equal load sharing among itself and all three planets.’
Due to normal manufacturing tolerances nevertheless, a sun gear which is securely set upon a shaft will intermittently have significantly more load on one planet equipment than on another equipment Hulstein explained. ‘By enabling the sun gear to float, it centres itself among the three planets and produces constant, equal load sharing.’
Equal load posting is just one of the benefits of this design. The floating sun gear provides ‘true involute actions,’ according to Hulstein. Accurate involute action happens when the rolling motion between the mating gears is really as complete as feasible. The benefit of this total meshing of gears is certainly longer reducer life, since less internal gear slippage means fewer damaged gear teeth.
That also means lower noise amounts. When the sun gear is allowed to completely roll into the planet gears, there’s much less ‘rattling’ as one’s teeth mesh. In place, the Ever-Power product offers ‘designed out’ the apparatus mesh sound by allowing the sun gear to float into place.
So why use a fixed sun gear at most? ‘Fixed sun gears tend to be used in accurate servo applications,’ Greg Pennings, Ever-Power Client Advocate, explained. ‘A set sun gear is necessary when precise positioning and low backlash are an intrinsic part of the application.’ Ever-Power engineers, however, were less concerned with low backlash and more interested with higher torque and/or lower sound applications.
Our planetary reducers with floating sun gears were made to contend with parallel shaft reducers, where backlash was less critical,’ Pennings said.
By using the floating sun gear concept, the Ever-Power planetary reducers have the ability to exceed the torque ratings of similar sized and bigger sized parallel shaft reducers, and yet maintain a lesser noise levels.
Sun, Ring and Planet
The most basic kind of planetary gearset is demonstrated in the figures above. The figure at still left shows a three-dimensional view while the figure at right provides a cross-section. In this geartrain, inputs and result can be taken from the carrier, ring and sunlight gears, and only the earth experiences epicyclic motion. This is the most common type of planetary gearset (with the exception of the differential) and it discovers application in speed reducers and automatic transmissions. sun planet gear Invest the aside a cordless drill, you’ll probably find this type of planetary gearset directly behind the drill chuck.
Two Suns – Two Planets gearset
Cross-sectional view
Two Suns, Two Planets
The gearset proven above has two sunlight gears, and the two planet gears (the yellow gears) rotate as a single unit. The sun gears (green and brown) can rotate independently of one another. The inputs and result can be selected from either sun gear and/or the carrier. High speed reductions can be achieved with this unit, but it can suffer from low efficiency if not designed correctly.
Red sun input – purple sun fixed
Purple sun input – red sun fixed
The animations above show the ‘two suns – two planets’ gearset with one sunlight as input and the other sun fixed. Remember that the carrier rotates clockwise in the computer animation at left and counterclockwise in the animation at right – despite the fact that the sun rotates counterclockwise in both cases.
The Differential
The gearset demonstrated above differs from the preceding gearsets in that it is composed of miter gears rather than spur (or helical) gears. The ‘sun’ gears are those that do not go through the epicyclic movement experienced by the earth. And the differential can be used to gauge the difference in rate between two shafts for the purpose of synchronization. In addition, the differential is often used in automotive drive trains to overcome the difference in wheel speed when a car goes around a corner.
