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 become aware of the benefits this unusual gear style can offer.
Traditionally, planetary reducers possess used a set sun gear, where in fact the centre gear is mounted on 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 fixed 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 design engineer Scott Hulstein said. ‘Because the sun gear is in continuous contact 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 fixed upon a shaft will intermittently have significantly more load using one planet gear than on another equipment Hulstein explained. ‘By permitting 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 movement between your mating gears is as complete as possible. The advantage of this complete meshing of gears can be longer reducer existence, since less internal gear slippage means fewer broken gear teeth.
That also means lower noise amounts. When sunlight gear is permitted 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 sunlight gear to float into place.
So why use a fixed sun gear at almost all? ‘Fixed sun gears are often used in accurate servo applications,’ Greg Pennings, Ever-Power Customer Advocate, explained. ‘A set sun gear is necessary when precise positioning and low backlash are an intrinsic part of the app.’ 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 contend with parallel shaft reducers, where backlash was less critical,’ Pennings said.
By using the floating sun gear concept, the Ever-Power planetary reducers can 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 shown in the figures above. The figure at remaining shows a three-dimensional watch as the figure at right provides a cross-section. In this geartrain, inputs and output can be taken from the carrier, band and sunlight gears, and just the planet experiences epicyclic motion. This is the most common kind of planetary gearset (with the exception of the differential) and it finds application in rate reducers and automatic 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 one another. The inputs and result can be selected from either sun gear and/or the carrier. Very high speed reductions may be accomplished with this unit, but it can have sun planet gear problems with low efficiency if not designed correctly.
Reddish colored sun input – purple sun fixed
Purple sun input – reddish colored sun fixed
The animations above show the ‘two suns – two planets’ gearset with one sunlight as input and the other sunlight fixed. Note that the carrier rotates clockwise in the animation at remaining and counterclockwise in the computer animation at right – even though the sun rotates counterclockwise in both cases.
The Differential
The gearset proven above differs from the preceding gearsets in 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 motion 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 often used in auto drive trains to overcome the difference in wheel velocity when a car encircles a corner.