Tham khảo tài liệu 'the design of rolling bearing mountings (fag bearing co) episode 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 87 Bucket wheel shaft of a bucket wheel excavator Bucket wheel excavators are mainly used for brown coal open pit mining. The bucket wheel shaft carries the bucket wheel the bull gear and the transmission housing. It is supported in the boom ends. Operating data Input power 3 x 735 kW theoretical conveying capacity 130 000 m3 day bucket wheel speed 3 min-1. Bearing selection The bearings of the bucket wheel shaft are subjected to high shock-type loads. Moreover shaft deflections and misalignments must be expected. For this reason only self-aligning roller bearings are suitable for supporting the shaft. At both shaft ends spherical roller bearings FAG 239 with withdrawal sleeves FAG AH39 900H are mounted as locating bearings. Thermal length variations of the shaft are compensated for by the elastic surrounding structure. The radial clearance of the spherical roller bearings is eliminated during mounting by pressing in the withdrawal sleeves. Only a split bearing can be provided on the bucket wheel side of the transmission box due to the solid forged shaft flange to which the bull gear is attached. If an unsplit bearing were to be provided on the opposite side of the transmission box it could only be replaced after dismounting the spherical roller bearing first. For this purpose the entire bucket wheel shaft would have to be removed from the boom. This is avoided by using a split FAG cylindrical roller bearing of dimensions 1 000 x 1 220 x 170 100 mm on this side as well. The increased axial clearance of the two cylindrical roller bearings yields a floating bearing arrangement. Each bearing accommodates axial guiding loads in only one direction. The inner ring halves are attached to the shaft by means of separate locking rings. The calculated nominal rating life of all bearings is over 75 000 hours. Machining tolerances All inner rings are subjected to circumferential load. The spherical roller bearings FAG 239 are hydraulically fastened to the shaft
