Tham khảo tài liệu 'the design of rolling bearing mountings (fag bearing co) episode 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 7 Mine fan motor Operating data Rated horsepower 1 800 kW speed n 750 min-1 Axial load Fa 130 kN radial load Fr kN the bearings are vertically arranged. Bearing selection The axial load of 130 kN is made up of the weight of the rotor and the two variable top and bottom fan impellers as well as the thrust of these fan impellers. They are supported by the upper thrust bearing. The radial loads on vertical motors are only guiding loads. They are very small and generally result from the unbalanced magnetic pull and the potential rotor unbalanced load. In the example shown the radial load per bearing is kN. If the exact values are not known these loads can be sufficiently taken into account assuming that half the rotor weight acts as the radial load at the rotor centre of gravity. The upper supporting bearing is a spherical roller thrust bearing FAG . Radial guidance is ensured by a deep groove ball bearing FAG 16068M mounted on the same sleeve as the supporting bearing and accommodating the opposing axial loads on the rotor. Axial guidance is necessary for transporting and mounting as well as for motor idling. In this operating condition the counterflow of air can cause reversal of rotation and thrust. The axial displacement is limited to 1 mm in the upward direction so that the spherical roller thrust bearing does not lift off. Springs arranged below the housing washer spring load 6 kN ensure continuous contact in the bearings. Radial guidance at the lower bearing position is provided by a deep groove ball bearing FAG 6340M it is mounted with a slide fit as the floating bearing. Since it is only lightly loaded it is preloaded with springs of 3 kN. Bearing dimensioning Spherical roller thrust bearing FAG has a dynamic load rating of C 1430 kN. The index of dynamic stressing fL is calculated with the axial load Fa 130 kN and the speedfactor for roller bearings fn n 750 min-1 . The nominal life Lh 65 000 hours. Based on the operating
