Small wind / Buyer questions
Mechanical interfaces
Can a bearing's dynamic load rating replace its static load rating?
The short answer
No. Dynamic and static bearing ratings address different assessment conditions. A wind-generator bearing can need both fatigue review during rotation and a check against excessive permanent contact deformation during heavy or stationary loading. One catalogue number cannot replace the other merely because both use force units.
Match the rating to the mechanism
The dynamic rating is used in a defined rolling-contact fatigue-life calculation. The static rating is linked to a specified contact-deformation criterion. Neither is simply the maximum external force that any installed bearing assembly can sustain. Contact geometry, combined radial/axial load and application conditions determine the appropriate equivalent load and required margin under the relevant manufacturer method.
Check stationary and rotating cases separately
A parked rotor can transmit substantial loads without accumulating the same revolutions used in a rotating fatigue calculation. A short heavy event may therefore matter to static assessment even if it contributes little operating time. Conversely, a lower load repeated over many revolutions can control a fatigue calculation. Schaeffler explicitly separates static contact capacity from fatigue-based sizing; a large dynamic rating does not waive the static case.
Request two identified checks where applicable
Ask the equipment designer to identify the actual load cases, equivalent static and dynamic loads, selected ratings and calculation basis. Keep bearing ratings separate from shaft, housing and retention capacities. For MARSTON equipment, the actual bearing and load history remain unconfirmed until supplied. Do not convert a catalogue rating into turbine kW, promise a service life or select a replacement from the larger of two numbers without the arrangement-specific assessment. Keep the bearing’s static check tied to its own equivalent-load definition. A designer should not divide static capacity by a dynamic equivalent load simply because both values happen to be reported in kilonewtons.
Sources
Examples are illustrative. Confirm product-specific performance, compatibility and supply scope in the applicable documents.