Lifespan and torque ratings

 

The graph below illustrates how lifetime of a gear stage evolves together with the input torque. This graph is for information only, using the ISO 6336-2 calculation methodology, and does not take bearings or seals into consideration

You may notice how sharp the decrease of lifetime is, after nominal torque is exceeded.

It should be noted that a planetary gearbox’s lifetime depends as well on seals, lubricant or bearings condition, and it can be affected by fast variations of torque or reversals (refer to the "application factors" section).

Reckon's published data results from dedicated software calculation, and products were tested in real-life conditions. We chose to follow the ISO 6336-2 calculation norm, as we consider it is a very safe method (it is used in the gear calculation of European space mechanisms). Our data is conservative, however it is important to note that indicated torque ratings or lifetimes can be affected by different factors:

  1. Temperature (calculation was based on a 40°C internal temperature), as lubricant viscosity differs with it. When the gearbox was selected properly, you should not notice more than a 40°C difference with the ambient temperature, and anyway the gearbox body (external housing) should never exceed 90°C.
  2. Speed (calculation was based on the rated speed indicated in the product datasheets). Exceeding this speed can increase the internal temperature and be prejudicial to the gears, bearings and seals lifetime. Make sure you do not routinely exceed the nominal speed value. If you need the gearbox to run faster than indicated on the datasheet, do not hesitate to contact us, we can usually modify the input stage so it accepts higher speeds.
  3. The Application Factor (see explanations on next pages). This is an empirical value based on experience, and you have to multiply it by your average nominal torque to get your rated torque evaluation.

As a conclusion, any published data should always be considered indicative because the data precisely corresponding to your application just does not exist.

Our engineers will give you an evaluation of your gearbox’s lifetime based on your application's real duty cycle and working conditions, using software calculation.