In-Line planetary gearboxes




Planetary gearboxes are prescribed in 2 different situations: as a one-to-one replacement of a competitor product, or in a new customer development.

Recommending an alternative product in an existing application is an easy task, as our engineers know that their design is safe. Reckon gearboxes can replace gearboxes of similar size and interface at no risk. In the second case, when customers design new systems, it is our responsibility to recommend a reliable solution that matches all specifications.
On a customer point of view, sizing a gearbox based on standard catalog ratings is increasingly seen as unprecise and risky, and a growing number of engineers begin to challenge datasheets values. We personally believe that the recent increase in some suppliers’ published product performance is intriguing and cannot be explained by a better design, better materials, treatments or lubricants.

Customers expect argued recommendation based on reliable data.

Explaining to our customer the reasons for the difference between our torque ratings and competition’s is not easy, as 10 different gear designers may give 10 different torque ratings to the same gearbox, based on which norm (or which version of the norm) they are following, the safety margin they choose to apply, the calculation scenario they decide to follow (speed, heat, value and localization of the shaft loads). To answer the question, one would need to know how this data was calculated, which is usually not explained in the catalogs. The gearbox given the highest torque rating is not necessarily the best, it might even mean that safety margins were removed to display nicer-looking data, which we see as misleading.
Datasheet ratings in our industry, when sincere, are often based on norms that can only consider a perfect scenario in which every part is perfectly located and manufactured, where the life of each individual component isn't impacted by the work of other components inside and outside the gearbox, where radial loads on the shaft only damage the output bearings of the gearbox, or the shaft itself. Real-life is different.
As our calculation software is able to take all these parameters into account, we can estimate real-life conditions more accurately than with any other software we used before. We can show how our products behave in any application.


While natively integrating most calculation norms including the latest updates of the ISO 6336-2:2006 for gear calculation and the TS 16281:2008 for bearing calculation, our software goes further and features additional algorithms.

Functions now available enable increasing design reliability and estimating very precisely the life of a complete gearbox, taking all aspects of real-life conditions into account. We can now estimate the life of each gearbox in our customers application, component by component, taking into account the impact on a component on the other, and, more importantly, considering your output element as a part or the system.


The following phenomenon is typical: in a rack and pinion transmission, the combined loads generated by the helical pinion are applied to the output shaft, they bend it, tilt it around the output bearings, twist the planet carrier, which compresses the ring gear onto the gears, the needles against the planets, the planets against the sun gear and finally applies a radial load on the customer motor shaft! As a result the sun gear suffers more than what the basic norms can estimate (basic algorithms will only give L10h results) and becomes the weak element in the system. Romax Enduro can tell us the damage to each of these elements!


Reckon ratings are conservative

The result of such calculation is obviously conservative when compared with standard datasheet ratings: in such or such application or working conditions, the same gearbox can be rated a certain torque value or only half of this value! Shafts, bearings, planet carriers, gears, needles, axles etc. all have their own stiffness. Who would prefer trusting catalog values that do not consider such a phenomenon?
Using Romax Enduro consequently makes our recommendations precise and professional: we now can tell you the difference in any internal element lifetime if you use a 25 teeth pinion rather than a 20 teeth pinion, as the resulting additional shaft torsion, flexion and tilt will reduce the size of the zone where the planets are transferred power from the sun gear, or transfer this power to the ring gear (this factor called the Khβ is clearly displayed in the results). 
Our engineers can show you that a 160 Nm gearbox is only a 120 Nm gearbox if you install a spiral bevel gear on its output shaft, because the radial and axial load generated by the bevel gear set will compress and deform the output bearings and tilt all the components inside above this torque. We can tell you that adding 2 teeth to your pinion and increasing the ratio slightly can sometimes increase, sometimes decrease the overall life, depending on the initial ratio.
Because even the greatest products cannot perform if poorly sized, we are ready to give our customers the perfect recommendation so their application achieves the longest lifetime and the best performance.

Related products

NEW Access line!

NEW Access line!

Access was developped to offer the lowest price on the market of low-backlash planetary gearboxes. Yet it features carburized and ground planets, 5 arc-min backlash, monobloc housing, NTN bearings and probably the best lubricant on the planet : our usual Sumico gear grease!

New torque ratings!

New torque ratings!

Internal gear design was improved on the X-Treme, Booster and Ultimate series, with an increase of power of up to 60%!

Silent and safe by design

Silent and safe by design

The PerfectPitch concept is a combination of features that we believe are necessary to provide silent, reliable planetary gearboxes.


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