When does a stationary bearing need a static-load check instead of a fatigue-life calculation?

LILY Bearing | 2026-10-28

Best answer

Static capacity addresses permanent contact deformation

JTEKT explains that sufficiently large static or impact loads can permanently deform the contacts between rolling elements and raceways.

The static rating and static equivalent load provide a framework for evaluating that concern. Dynamic rating life, by contrast, addresses repeated rolling-contact fatigue under its stated assumptions. A bearing may experience both kinds of loading during one duty cycle. For example, its normal running load can be moderate while a stationary handling operation imposes a much larger force. The existence of a favourable running-life calculation says little about that separate event. Identify the load cases before deciding which calculations the machine needs.

Make a load ledger that includes stopped-machine events

Use separate entries for normal running, start-up, shutdown, standstill and unusual impact events.

For each, record force direction, estimated or measured magnitude, duration and the evidence behind the value. Flag the stopped or shock cases for the appropriate static assessment instead of averaging them into a running load. A slow turn during inspection should not erase a larger standstill force from the record. The required static safety basis still comes from the exact bearing, machine duty and responsible engineering criteria. This ledger organises the evidence; it does not supply a universal safety factor or imply that any non-rotating bearing is adequately sized.