Bearings, units and housings -- Super-precision bearings -- Angular contact ball bearings -- Angular contact ball bearings, super-precision -- SKF 71921 ACD/P4AH1
71921 ACD/P4AH1
Dimensions
| d | 105 | mm | |
| D | 145 | mm | |
| B | 20 | mm | |
| d1 | 117.3 | mm | |
| d2 | 117.3 | mm | |
| D1 | 132.7 | mm | |
| K | 0.5 | mm | |
| C1 | 5.46 | mm | |
| r1,2 | min. | 1.1 | mm |
| r3,4 | min. | 0.6 | mm |
| a | 39.3 | mm |
Abutment dimensions
| da | min. | 111 | mm |
| db | min. | 111 | mm |
| Da | max. | 139 | mm |
| Db | max. | 141 | mm |
| ra | max. | 1 | mm |
| rb | max. | 0.6 | mm |
| dn | 120.6 | mm |
Calculation data
| Basic dynamic load rating | C | 57.2 | kN | |
| Basic static load rating | C0 | 65.5 | kN | |
| Fatigue load limit | Pu | 2.5 | kN | |
| Attainable speed for grease lubrication | 7500 | r/min | ||
| Attainable speed for oil-air lubrication | 12000 | r/min | ||
| Ball diameter | Dw | 12.7 | mm | |
| Number of balls | z | 27 | ||
| Reference grease quantity | Gref | 11.1 | cm³ | |
| Preload and stiffness (back-to-back, face-to-face) | ||||
| Preload class A | GA | 360 | N | |
| Static axial stiffness, preload class A | 263 | N/µm | ||
| Preload class B | GB | 720 | N | |
| Static axial stiffness, preload class B | 346 | N/µm | ||
| Preload class C | GC | 1440 | N | |
| Static axial stiffness, preload class C | 463 | N/µm | ||
| Preload class D | GD | 2880 | N | |
| Static axial stiffness, preload class D | 633 | N/µm | ||
| Calculation factors | ||||
| Calculation factor | f | 1.25 | ||
| Calculation factor | f1 | 0.98 | ||
| Calculation factor | f2A | 1 | ||
| Calculation factor | f2B | 1.04 | ||
| Calculation factor | f2C | 1.08 | ||
| Calculation factor | f2D | 1.14 | ||
| Calculation factor | fHC | 1 | ||
| Calculation factor | e | 0.68 | ||
| Calculation factor (single, tandem) | Y2 | 0.87 | ||
| Calculation factor (single, tandem) | Y0 | 0.38 | ||
| Calculation factor (single, tandem) | X2 | 0.41 | ||
| Calculation factor (back-to-back, face-to-face) | Y1 | 0.92 | ||
| Calculation factor (back-to-back, face-to-face) | Y2 | 1.41 | ||
| Calculation factor (back-to-back, face-to-face) | Y0 | 0.76 | ||
| Calculation factor (back-to-back, face-to-face) | X2 | 0.67 | ||
Mass
| Mass bearing | 0.82 | kg |