Ever-Power new planetary reducers employ a floating sun equipment rather than a fixed position one.
The word ”There’s nothing new under the sun’ certainly pertains to planetary reducers. And, while floating sunlight gears have already been around quite a while, some engineers might not become aware of the huge benefits this unusual gear design can offer.
Traditionally, planetary reducers have used a fixed sun gear, where the centre gear is mounted on or machined in to the shaft. When this fixed sun gear revolves, it turns the planet gears to create movement and/or power. Ever-Power new planetary reducers, however, are having a floating sun gear rather than a fixed position sun gear.
Why a floating sunlight gear? ‘In the planetary concept, the sun is the driver, or pinion, in the gear set,’Ever-Power style engineer Scott Hulstein said. ‘Because the sun gear is in constant contact with the planets, it’s important that it’s properly centred among the three planets to be able to sun planet gear provide equal load sharing among itself and all three planets.’
Because of normal manufacturing tolerances nevertheless, a sun equipment which is securely fixed on a shaft will intermittently have significantly more load on one planet equipment than on another equipment Hulstein explained. ‘By allowing the sun equipment to float, it centres itself among the three planets and creates constant, equal load sharing.’
Equal load posting is merely one of the benefits of this design. The floating sun gear provides ‘accurate involute action,’ according to Hulstein. Accurate involute action happens when the rolling motion between the mating gears is really as complete as possible. The benefit of this complete meshing of gears is definitely longer reducer lifestyle, since less internal gear slippage means fewer damaged gear teeth.
That also means lower noise amounts. When the sun gear is permitted to completely roll into the planet gears, there’s less ‘rattling’ as the teeth mesh. In effect, the Ever-Power product offers ‘designed out’ the apparatus mesh noise by allowing the sun gear to float into place.
So why make use of a set sun gear at every? ‘Fixed sun gears are often used in accurate servo applications,’ Greg Pennings, Ever-Power Customer Advocate, explained. ‘A fixed sun gear is essential when specific 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 noise applications.
Our planetary reducers with floating sun gears were made to compete with parallel shaft reducers, where backlash was less critical,’ Pennings said.
By using the floating sun gear concept, the Ever-Power planetary reducers can easily exceed the torque rankings of similar sized and larger sized parallel shaft reducers, and yet maintain a lower noise levels.
Sun, Ring and Planet
The most basic kind of planetary gearset is demonstrated in the figures above. The figure at left shows a three-dimensional look at as the figure at right offers a cross-section. In this geartrain, inputs and output can be taken from the carrier, ring and sun gears, and only the planet experiences epicyclic motion. This is the many common kind of planetary gearset (with the exception of the differential) and it discovers application in quickness reducers and automatic transmissions. Invest the apart a cordless drill, you will most probably find this type of planetary gearset right behind the drill chuck.
Two Suns – Two Planets gearset
Cross-sectional view
Two Suns, Two Planets
The gearset shown above has two sun gears, and the two planet gears (the yellow gears) rotate as a single unit. The sun gears (green and dark brown) can rotate independently of one another. The inputs and result can be chosen from either sun equipment and/or the carrier. High speed reductions can be achieved with this unit, but it can have problems with low efficiency if not really designed correctly.
Crimson sun input – purple sun fixed
Purple sun input – reddish 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 remaining and counterclockwise in the computer animation at right – despite the fact that sunlight rotates counterclockwise in both instances.
The Differential
The gearset demonstrated above is different 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 undergo the epicyclic movement experienced by the planet. And the differential can be used to measure the difference in rate between two shafts for the intended purpose of synchronization. In addition, the differential is frequently used in automotive drive trains to get over the difference in wheel acceleration when a car encircles a corner.