Bearings, units and housings -- Super-precision bearings -- Angular contact ball bearings -- Angular contact ball bearings, super-precision -- SKF 71821 ACD/P4
71821 ACD/P4
Dimensions
| d | 105 | mm | |
| D | 130 | mm | |
| B | 13 | mm | |
| d1 | 113.2 | mm | |
| d2 | 113.2 | mm | |
| D1 | 122 | mm | |
| r1,2 | min. | 1 | mm |
| r3,4 | min. | 0.3 | mm |
| a | 34 | mm |
Abutment dimensions
| da | min. | 109.6 | mm |
| db | min. | 109.6 | mm |
| Da | max. | 125.4 | mm |
| Db | max. | 128 | mm |
| ra | max. | 1 | mm |
| rb | max. | 0.3 | mm |
| dn | 114.6 | mm |
Calculation data
| Basic dynamic load rating | C | 21.6 | kN | |
| Basic static load rating | C0 | 28.5 | kN | |
| Fatigue load limit | Pu | 1.1 | kN | |
| Attainable speed for grease lubrication | 8000 | r/min | ||
| Attainable speed for oil-air lubrication | 12000 | r/min | ||
| Ball diameter | Dw | 7.144 | mm | |
| Number of balls | z | 35 | ||
| Reference grease quantity | Gref | 4 | cm³ | |
| Preload and stiffness (back-to-back, face-to-face) | ||||
| Preload class A | GA | 200 | N | |
| Static axial stiffness, preload class A | 220 | N/µm | ||
| Preload class B | GB | 600 | N | |
| Static axial stiffness, preload class B | 353 | N/µm | ||
| Preload class C | GC | 1200 | N | |
| Static axial stiffness, preload class C | 488 | N/µm | ||
| Calculation factors | ||||
| Calculation factor | f | 1.44 | ||
| Calculation factor | f1 | 0.97 | ||
| Calculation factor | f2A | 1 | ||
| Calculation factor | f2B | 1.08 | ||
| Calculation factor | f2C | 1.15 | ||
| 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 | 0.32 | kg |