• Deflection

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The rigidity is determined by the type, size and operating clearance of the bearing. This increases with the number of rolling elements supporting the load. Rolling bearings with line contact have a higher rigidity than rolling bearings with point contact, Figure 1.

δ = displacement Fr = radial bearing load Figure 1 Rigidity, as a function of bearing type

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Deflection

Rolling bearings have a progressive deflection rate. The displacement values can be determined using approximation formulae.

The formulae are valid for bearings without misalignment and with a rigid surrounding structure. In axial bearings, a concentrically acting load is assumed.

cS  N0,84/μm Rigidity parameter d  mm Bearing bore diameter δr  μm Radial displacement between shaft axis and centre of bore, Figure 2 δa  μm Axial displacement between shaft locating washer and housing locating washer, Figure 3 s  μm Radial operating clearance of fitted, unloaded bearing Fr  N Radial bearing load Fa  N Axial bearing load Fav  N Axial preload force Kc Factor for determining the rigidity parameter, see table.

Factor Kc

Bearing series Factor Kc Series Factor Kc SL1818 12,8 NJ2..-E 11,1 SL1829, SL1830, SL1923 16 NJ3..-E 11,3 SL1850, SL0148, SL0248, SL0249 29,2 NJ22..-E 15,4 NA48 24,9 NJ23..-E 16,9 NA49 23,5 NU10 9,5 NA69 37,3 NU19 11,3 NKIS 21,3 NN30..-AS-K 18,6 NKI 4,4 · B0,8/d0,2 ZNR31-22 21,1 HK, BK 4,2 · C0,8/d0,2 ZNR31-23 23,2 K811, 811, K812, 812 36,7 ZNR31-30 30 K893, 893, K894, 894 59,7 ZNR31-31 29,3 ZNR31-32 28,9

Radial cylindrical roller bearings δr = radial displacement Fr = radial bearing load Figure 2 Radial displacement

Axial cylindrical roller bearing δa = axial displacement Fa = axial bearing load Fav = axial preload force Figure 3 Axial displacement

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