Requisite minimum load

In applications where the bearing size is determined by factors other than load – for example, shaft diameter constrained by critical speed – the bearing may be lightly loaded in relation to its size and carrying capacity. Where there are very light loads, failure mechanisms other than fatigue, such as skidding and smearing of raceways or cage damage, often prevail. To provide satisfactory operation, rolling bearings must always be subjected to a given minimum load. As a general rule, minimum loads of 0,01 C should be imposed on ball bearings and 0,02 C on roller bearings. More accurate minimum load requirements are given in the product sections.

The importance of applying a minimum load is greater in applications where there are rapid accelerations or rapid starts and stops, and where speeds exceed 50% of the limiting speeds listed in the product tables (→ Speed limitations). If minimum load requirements cannot be met, potential improvements are:

  • Use a bearing with a smaller dimension series.
  • Consider special lubrication or running-in procedures.
  • Consider NoWear coated bearings.
  • Consider applying a preload.
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