The Design of Rolling Bearing Mountings

29 Bevel gear – spur gear transmissionOperating dataInput speed 1,000 min –1 ; gear ratio 6.25:1; inputpower 135 kW.Bearing selection, dimensioningPinion shaftThe pinion is an overhung arrangement. Two taperedroller bearings FAG 31315.A100.140.N11CA in Xarrangement are mounted at the locating end. Spacer Abetween the cups adjusts the bearing pair to achieve anaxial clearance of 100...140 µm prior to mounting.The floating bearing, a cylindrical roller bearing FAGNUP2315E.TVP2, has a tight fit on the shaft and aslide fit in the housing.Axial pinion adjustment is achieved by grinding thespacers B and C to suitable width.Crown wheel shaftThe crown wheel shaft is supported by two taperedroller bearings FAG 30320A (T2GB100 - DIN ISO355). The bearings are mounted in X arrangement andare adjusted through the cups. For axial adjustmentand adjustment of the axial clearance the spacers D andE are ground to suitable width.Output shaftThe output shaft is supported by two spherical rollerbearings FAG 23028ES.TVPB in floating bearingarrangement.Detrimental axial preloads are avoided by means of agap between the covers and outer rings.For the floating bearing of the pinion shaft an index ofdynamic stressing f L = 2.88 is calculated. This value correspondsto a nominal life of L h = 17,000 hours. Takinginto account the operating conditions such as:– oil ISO VG220 with suitable additives,– a good degree of cleanliness in the lubricating gap,– max. operating temperature 80 °C,a factor a 23 = 3 is obtained with the adjusted life calculation.Therefore, the attainable life L hna = 50,700 hours.Machining tolerancesThe bearing inner rings are subjected to circumferentialloads and consequently have to be fitted tightly on theshaft. The bearing seats for the pinion bearings mustbe machined to the following tolerances: Shaft tom5 / housing to H6.Lubrication, sealingAll bearings are sufficiently lubricated with the splashoil from the gears. The tapered roller bearing pair issupplied with oil which is fed through ducts from collectingpockets in the upper housing part.Shaft seals are fitted at the shaft openings.29: Bevel gear-spur gear transmission45 FAG