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Ever-Power new planetary reducers hire a floating sun equipment rather than a fixed position one.
The word ”There’s nothing new beneath the sun’ certainly applies to planetary reducers. And, while floating sunlight gears have already been around quite a while, some engineers might not be aware of the huge benefits this unusual gear style 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 fixed sun gear 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 set position sun gear.
Why a floating sunlight gear? ‘In the planetary idea, the sun may be the driver, or pinion, in the gear set,’Ever-Power design engineer Scott Hulstein said. ‘Because the sun gear is in continuous connection with the planets, it’s important that it is perfectly centred among the three planets in order to provide equal load sharing among itself and all three planets.’
Because of normal manufacturing tolerances however, a sun equipment which is securely set on a shaft will intermittently have more load using one planet equipment 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 sharing is merely one of the benefits of this design. The floating sun gear provides ‘true involute actions,’ according to Hulstein. Accurate involute action takes place when the rolling movement between the mating gears is as complete as possible. The advantage of this finish meshing of gears can be longer reducer life, since less internal equipment slippage means fewer damaged gear teeth.
That does mean lower noise levels. When sunlight gear is permitted to completely roll in to the planet gears, there’s much less ‘rattling’ as the teeth mesh. In effect, the Ever-Power product provides ‘designed out’ the gear mesh sound by allowing the sun equipment to float into place.
So why use a set sun gear at every? ‘Fixed sun gears tend to be used in true servo applications,’ Greg Pennings, Ever-Power Consumer Advocate, explained. ‘A fixed sun gear is essential when exact positioning and low backlash are an integral part of the application.’ Ever-Power engineers, however, were less worried about low backlash and more interested with higher torque and/or lower sound applications.
Our planetary reducers with floating sun gears were designed to compete 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 bigger sized parallel shaft reducers, and yet maintain a lower noise levels.
Sun, Ring and Planet
The most basic type of planetary gearset is shown 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 extracted from the carrier, band and sun gears, and just the earth experiences sun planet gear epicyclic motion. That is the most common type of planetary gearset (apart from the differential) and it finds application in swiftness reducers and automated transmissions. If you take aside a cordless drill, you will most 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 shown 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 selected from either sun equipment and/or the carrier. Very high speed reductions can be achieved with this unit, but it can have problems with low efficiency if not really designed correctly.
Reddish sun input – purple sun fixed
Purple sun input – crimson 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 animation at remaining and counterclockwise in the animation at right – despite the fact that the sun rotates counterclockwise in both instances.
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 the ones that do not undergo the epicyclic movement experienced by the planet. And the differential can be utilized to measure the difference in velocity between two shafts for the purpose of synchronization. Furthermore, the differential is frequently used in automotive drive trains to overcome the difference in wheel speed when a car goes around a corner.