Comparing data

 

There is no standard way of presenting data.

 

For any gearbox, a variety of ratings could be published, depending on choices made by the engineer calculating them, for instance:

 

  • Calculating bearing capacity with a slower rotation speed: doing so exaggerates the expected lifespan and/or the torque and admissible efforts on shaft

  • ​Calculating ratings using an L10 life: this option allows 10% of products to fail before the expected lifetime. 

  • Reducing the safety factors used when proceeding to the calculation: results can vary immensely with a similar product.

 

Beware of abnormally high torque ratings as they can be misleading!

 

Safety first!

 

  • ​We do not add L10 factors to our calculation because it inflates torque ratings artificially and we consider it misleading. Who would accept a 10% failure rate before normal lifetime?
  • Bearing and gear calculation consider rotation speeds, temperature and application factors corresponding to real-life needs (ex: 3,000 rpm for a size 90 mm gearbox).

 

Lifetime of a gear stage is not proportional to the output torque.

 

When a gearbox is properly sized for an application, the theoretical gearing lifetime is theoretically unlimited. This is how our designing software calls it when the film of lubricant between the gears is still thick enough to protect them from working "metal-against-metal". It means as well that fatigue breakage will not happen under such conditions.

Lifespan then depends greatly on the lubricant and seals condition.

 

At Reckon,

 

  • Theoretical gearing life is unlimited if your rated torque is under T2n
  • Theoretical gearing life is 20,000h if your rated torque is T2n
  • Acceleration torque can be used 2,000 hours if it is under Tmax