In-Line planetary gearboxes

Application factors


Using the right application factor is key to guarantee that your gearbox will not lose precision nor break. As many applications do not work homogeneously, the ISO and DIN institutes defined application factors. We based our application factors on them.

Once you have identified what application factor corresponds to your duty cycle, you need to multiply your "continuous torque" ("X" in the diagrams below) by the application factor. The application factors below are indicative and should be viewed as a minimal requirement, as every application is different. Selecting them is empirical. You may find more explanation in norms ISO 6336, DIN 3990 and DIN 3991.


Ka = 1: continuous, stable operation with DC motor like mixers in liquid, uniformly-loaded conveyor, escalator, metal coiler etc. Never use Ka=1 with a servomotor.

Ka=1.1: continuous, stable operation with a servomotor (examples here-above)


Ka=1.25: conveyors, extruder feeders with belts, meat grinders, cable reels, dough mixers etc

 Ka=1.35: dryers etc.

Ka=1.5: radars, wire winding machines

Ka=1.7: stone crushers, extruder screw, plastic mixers, fast pick&place robots for plasturgy, tool changers



Ka = 1.8: punching machines, fast laser-welding machines

Ka = 2.5: delta robots, compactors...

Ka> 2.5 include cranes (2.5 to 3), piston engines etc.





Note: the red circles represent reversals. Always make sure that your reversals are ramped-up or down cautiously, to avoid shocks on teeth inside the gearbox. Internal shocks are the reason why we recomment to use a low-backlash gearbox (<5 arc-min) until Ka=1.8 and very low-Backlash (Ultra low-backlash option available all most series except Wiser)



For servomotor applications subject to shocks, the norm DIN 3990 recommends multiplying your average torque by one of the following parameters:

  • Moderate shocks : Ka=1.35
  • Medium shocks : Ka=1.60
  • Heavy shocks : Ka=1.85



  • T°<25°C : Kt = 1.00 (unventilated) or 0.9 (ventilated)
  • T°<35°C : Kt = 1.10 (unventilated) or 1 (ventilated)
  • T°<45°C : Kt = 1.25 (unventilated) or 1.15 (ventilated)

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