Ever-Power new planetary reducers hire a floating sun gear rather than a set position one.
The saying ”There’s nothing new beneath the sun’ certainly applies to planetary reducers. And, while floating sunlight gears have been around a long time, some engineers may not end up being aware of the benefits this unusual gear design can offer.
Traditionally, planetary reducers possess used a fixed sun gear, where the centre gear is attached to or machined into the shaft. When this set sun equipment revolves, it turns the planet gears to create motion and/or power. Ever-Power new planetary reducers, however, are having a floating sun gear rather than a set position sun gear.
Why a floating sun equipment? ‘In the planetary concept, the sun is the driver, or pinion, in the gear set,’Ever-Power design engineer Scott Hulstein stated. ‘Because the sun gear is in constant connection with the planets, it’s important that it is flawlessly centred among the three planets to be able to provide equal load posting among itself and all three planets.’
Because of normal manufacturing tolerances however, a sun gear which is securely set upon a shaft will intermittently have significantly more load on one planet equipment than on another gear Hulstein explained. ‘By enabling the sun gear to float, it centres itself among the three planets and generates continuous, equal load sharing.’
Equal load posting is merely one of the benefits of this design. The floating sun gear provides ‘true involute action,’ according to Hulstein. True involute action occurs when the rolling movement between the mating gears is really as complete as possible. The advantage of this total meshing of gears is usually 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 world gears, there’s less ‘rattling’ as the teeth mesh. In effect, the Ever-Power product provides ‘designed out’ the gear mesh noise by allowing the sun equipment to float into place.
So why use a set sun gear at all? ‘Fixed sun gears are often used in accurate servo applications,’ Greg Pennings, Ever-Power Customer Advocate, explained. ‘A fixed sun gear is necessary when precise positioning and low backlash are an integral part of the software.’ 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 sunlight gears were designed to contend with parallel shaft reducers, where backlash was less critical,’ Pennings said.
Utilizing the floating sun equipment concept, the Ever-Power planetary reducers are able to exceed the torque ratings of similar sized and larger sized parallel shaft reducers, yet maintain a lesser noise levels.
Sun, Ring and Planet
The most basic type of planetary gearset is shown in the figures above. The figure at left shows a three-dimensional watch while the figure at right offers a cross-section. In this geartrain, inputs and output can be taken from the carrier, band and sun gears, and just the earth experiences epicyclic motion. That is the many common type of planetary gearset (with the exception of the differential) and it finds application in quickness reducers and automatic transmissions. If you take aside 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 proven above has two sun gears, and the two planet gears (the yellow gears) rotate as an individual unit. The sun gears (green and brownish) can rotate independently of 1 another. The inputs and output can be chosen from either sun equipment and/or the carrier. Very high speed reductions can be achieved with this unit, nonetheless it can suffer from low efficiency if not designed correctly.
Reddish colored sun input – purple sun fixed
Purple sun input – red sun fixed
The animations above show the ‘two suns – two planets’ gearset with one sun as input and the other sunlight fixed. Note that the carrier rotates clockwise in the computer animation at sun planet gear remaining and counterclockwise in the animation at right – even though the sun rotates counterclockwise in both instances.
The Differential
The gearset demonstrated above differs from the preceding gearsets for the reason that it is composed of miter gears instead of spur (or helical) gears. The ‘sun’ gears are those that do not go through the epicyclic movement experienced by the planet. And the differential can be used to gauge the difference in speed between two shafts for the purpose of synchronization. In addition, the differential is frequently used in automotive drive trains to overcome the difference in wheel speed when a car encircles a corner.