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Which planetary gear is the right one?

In planetary gears, several planetary wheels roll between a ring gear and a centrally mounted sun gear. This design offers the advantage that, even with a compact design, high torques can be transmitted due to the load distribution across several planetary wheels. The drive and output shafts are in alignment, so there is no offset.

Planetary gears have a wide range of applications. They can be found in equipment, conveyor, and medical technology, as well as in barriers, door drives, e-bikes or in packaging technology. With this variety of applications, it is clear that different planetary gears are needed to meet the wide range of application requirements. After all, even planetary gears are not an all-in-one solution. Drive specialist ebm‑papst therefore has several models in its product range, as users always need a solution that fits their application perfectly and does exactly what is needed.

In planetary gears produced on the production lines (Fig. 1) in Lauf near Nuremberg, the range therefore extends from planetary gears optimized for “simple” applications according to economic criteria, to high-torque or particularly smooth-running variants, right up to highly robust solutions that also offer high overload capacity. Here, the different gear designs have a basic principle in common: Their modular design provides an unusually high number of different reduction ratios in close increments. The reduction ratios are designed in harmonized stages and are deliberately finer particularly when it comes to the area of low output power.

With corresponding experience and sophisticated manufacturing technology, planetary gears can also be adapted to different application requirements. (Graphic | ebm-papst)
With corresponding experience and sophisticated manufacturing technology, planetary gears can also be adapted to different application requirements. (Graphic | ebm-papst)

For high torque

PerformaxPlus planetary gears (Fig. 2) are perfect, for example, for users who are looking for smooth, robust gear unit solutions for high torques. The gear design makes the best possible use of the available installation space: By using a radial screw connection for the individual housing components, a maximum effective diameter is available for the ring gear toothing. In contrast, solutions with an axial screw connection – as is otherwise common – limit the installation space available for the toothing so that only relatively small ring gear diameters are possible and therefore only limited loads can be transmitted. Due to large tooth widths in the input stage and the increased strength of the ring gear toothing made of hardened steel in the output stage, PerformaxPlus is particularly suitable for the high torques which are in demand, for example, in door technology and automation. At the same time, the steel housing ensures shock resistance. The optional HRL radial load stage can also be used to handle extra high radial loads, e.g. for belt pretensioning. Depending on the output speed, radial forces of up to 2,000 N can be transferred.

Due to greater tooth widths in the input stage and the increased strength of the ring gear toothing made of hardened steel in the output stage, the PerformaxPlus planetary gear is particularly suitable for high torques. (Graphic | ebm-papst)
Due to greater tooth widths in the input stage and the increased strength of the ring gear toothing made of hardened steel in the output stage, the PerformaxPlus planetary gear is particularly suitable for high torques. (Graphic | ebm-papst)

Compact all-rounder

The Performax planetary gear (Fig. 3) designed for “more simple” applications is also based on the radial screw design. It is therefore ideal for users who are looking for an efficient, economical gear solution, e.g. for use in medical rehabilitation equipment or conveyor technology.

Helically toothed plastic impellers in the first stage ensure smooth operation, while the zinc die-cast ring gear in the second stage makes the production process economical. Thanks to the reduction ratio of 17:1 in the first stage alone, it is also possible to use a single-stage gear unit where two stages would normally be required. Instead of three, this gear unit works with reduction ratios up to 204:1 with just two stages. This saves space, increases efficiency, and also reduces costs.

The compact Performax gears are all-rounders and impress with their high power density. Thanks to the reduction ratio of 17:1 in the first stage alone, it is also possible to use a single-stage gear unit where two stages would normally be required. (Graphic | ebm-papst)
The compact Performax gears are all-rounders and impress with their high power density. Thanks to the reduction ratio of 17:1 in the first stage alone, it is also possible to use a single-stage gear unit where two stages would normally be required. (Graphic | ebm-papst)

Extremely smooth, quiet operation

In medical technology, there are many applications in which gear units need to be as quiet as possible, especially when the drives are operating close to the patient. Typical examples can be found in dialysis, on operating tables, or in diagnostics. Operation must be as smooth as possible here. The NoiselessPlus gears are a good choice in such cases. Their aluminum housing and the precise, noise-optimized helical toothing of the vibration-absorbing plastic impellers in both stages significantly reduce noise emissions. The noise level is load-independent even under extreme operating conditions and the double ball bearing of the output shaft means that even high radial loads do not reduce the service life. The single-stage or two-stage versions offer a wide range of reduction ratios from 4.33:1 to 231:1. Thanks to the machining of the housing during production, high flexibility is possible when it comes to customer connection.

Applications in intralogistics, such as a sorting diverter, demand compact, powerful and rugged gear units. Optimax planetary gears can stand out here. (Graphic | nullplus / Adobe Stock)
Applications in intralogistics, such as a sorting diverter, demand compact, powerful and rugged gear units. Optimax planetary gears can stand out here. (Graphic | nullplus / Adobe Stock)

Robust and powerful

Today, many industrial automation applications, as well as intralogistics applications, call for compact, powerful and simultaneously robust gear units (Fig. 4). Typical examples include shuttle vehicles or crossbelt conveyors. Here, the Optimax planetary gears, which are available in two sizes (Fig. 5), stand out. The larger variant, for example, offers peak torques of up to 150 Nm with an installation edge dimension of 63 mm and a length of just 102 mm in the 2-stage version. The finely coordinated reduction series ranges from 3:1 to 5:1 right up to 9:1 in the single-stage range. The two-stage version is available with reduction ratios 9:1, 15:1, 25:1 and 45:1.

Robustness is not only achieved by producing all gear tooth parts from hardened steel, but also by the design: Despite the small edge dimension, a very large ring gear diameter was realized, as the four axial fastening screws are placed in the corners of the square. Even high radial loads resulting from toothed belts or cams are not critical. The output stage has a very rigid design with two large ball bearings and thus offers a maintenance-free, calculated service life of up to 20,000 h in nominal operation with 500 N radial load. The gear units can be easily combined with 63 and 80-mm motors. For the smaller 42-mm motors, Optimax 42 is also a very robust, overload-resistant one or two-stage planetary gear, which is available with IP54 degree of protection as standard and rounds off the range.

Systematic drive solution

The planetary gears described are part of the sophisticated ebm‑papst modular system and can be combined with all DC and EC motors. With the modern ECI motor families, for example, there is a wide range of dynamic motors, control electronics, gear units, and brake and sensor modules that can be combined to create a tailor-made drive. Individual complete drive solutions from a single source with perfectly matched components are therefore easy to realize and can be put together in the online portal, for example. Several thousand variants are possible in total. Defined preferred types are ready for shipment within just 48 hours, making them available unusually fast for sampling. 

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