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.

Fig. 1: With corre­sponding expe­ri­ence and sophis­ti­cated manu­fac­turing tech­nology, plan­e­tary gears can also be adapted to different appli­ca­tion require­ments. (Graphic | ebm-papst)

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.

To meet the wide range of appli­ca­tion require­ments, different plan­e­tary gears are 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.

For high torque

Fig. 2: 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)

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.

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.

Fig. 3: 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)

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.

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.

Fig. 4: 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.

Fig. 5: Robust Optimax gear: All toothing parts are made of hard­ened steel and, despite the small edge dimen­sion, a very large ring gear diam­eter was real­ized, as the four axial fastening screws are posi­tioned in the corners of the square. (Graphic | ebm-papst)

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.