The Design of Rolling Bearing Mountings

GlossaryDiagram for determining the cleanliness factor sa Diagram for improved to utmost cleanlinessb Diagram for moderately contaminated lubricant and heavily contaminated lubricantκ=4κ=3.5κ=3κ=2.5κ=2κ=1.5κ=1κ=0.9κ=0.8κ=0.7V = 1V = 0.5 V = 0.3κ=0.6κ=0.5a:b:2.5 3 4 5 6 7 8 9 10 12 14 16 20 1 2 3 5 10 15 20 30Stress index f s*Cleanliness factor s1V = 1 0.70.5V = 20.30.2V = 3A cleanliness factor s > 1 is attainable for fullcomplementbearings only if wear in roller/roller0.1contact is eliminated by a high-viscosity lubricantand utmost cleanliness (oil cleanliness according0.05to ISO 4406 at least 11/7).0.03Cleanliness factor sConsistencyMeasure of the resistance of a lubricating grease tobeing deformed.Consistency classification to NLGI, cp. Penetration.Contact angle The contact angle is the angle formed by the contactlines of the rolling elements and the radial plane of thebearing. 0 refers to the nominal contact angle, i.e. thecontact angle of the load-free bearing.Under axial loads the contact angle of deep groove ballbearings, angular contact ball bearings etc. increases.Under a combined load it changes from one rolling elementto the next. These changing contact angles aretaken into account when calculating the pressure distributionwithin the bearing.Ball bearings and roller bearings with symmetrical rollingelements have identical contact angles at their innerrings and outer rings. In roller bearings with asymmetricalrollers the contact angles at inner ring and outerring are not identical. The equilibrium of forces inthese bearings is maintained by a force componentwhich is directed towards the lip.Contact lineαThe rolling elements transmit loads from one bearingring to the other in the direction of the contact lines.181 FAG