The Design of Rolling Bearing Mountings

43–44 UIC axle box roller bearings for freight carsThe car body is supported by laminated springs on thewheelset.The laminated springs have the additionaljob of guiding the wheelset. To limit the swaying motionof the car body and to accommodate the thrustpeaks, the housing features guiding surfaces in whichthe axle support of the frame is engaged. Cylindrical orspherical roller bearings are used as axle box rollerbearings. The housing boundary dimensions of theUIC bearing are standardized. According to the latestUIC conditions 130 mm diameter journals are specifiedfor cylindrical and spherical roller bearings. Insome cases 120 mm journals are used for cylindricalroller bearings.ClearanceThe tight fit expands the inner ring thus reducingradial clearance. A further clearance reduction resultsfrom the air stream developed during travel whichcools the outer ring more than the inner ring. Therefore,cylindrical roller bearings with a radial clearanceof 130 to 180 microns and spherical roller bearingswith increased radial clearance C3 are chosen.Lubrication, sealingThe axle box roller bearings are lubricated with a lithiumsoap base grease. Felt seals combined with a labyrinthhave proved most effective for cylindrical rollerbearings.UIC axle boxes with spherical roller bearings invariablyuse only labyrinth seals.Dimensioning, bearing selectionOperating data 43: UIC axle boxes with 44: UIC axle boxes withcylindrical roller bearings spherical roller bearingsDeadweight with max. payload G max 40,000 kg 40,000 kgTop speed v max 100 km/h 100 km/hWheel diameter D R 1 m 1 mNumber of wheelsets 2 2Wheelset weight G R 1,300 kg 1,300 kgWeight on axle A 20,000 kg 20,000 kgNumber of bearings per wheelset i R4 cylindrical roller bearings 4 spherical roller bearingsSupplementary factor f z · f a 1.3 · 1 = 1.3 1.3 · 1.25 = 1.625(f a = 1 for cylindrical roller bearings where thrust loadsare taken up by the lips;f a = 1.25 for spherical roller bearings where thrust loadsare taken up by the raceways.)Equivalent load:P = (A – G R ) · g · f z · f a /i R (g = 9.81 m/s 2 ) 59.6 kN 74.5 kNAverage travelling speed (v Fm = 0.75 · v max ) 75 km/h 75 km/hAverage wheelset speed n = 5,310 · v Fm (km/h)/D R (mm) 400 min –1 400 min –1Speed factor f n 0.475 0.475Index of dynamic stressing f L 3.5 3.5Required dynamic load rating of one bearing:C = f L /f n · P 439 kN 549 kNBearings mounted: Cylindrical roller bearings 2 spherical roller bearingsFAG WJ130x240TVP and FAG 502472AAFAG WJP130x240P.TVPBore x outside diameter x width 130 x 240 x 80 mm 130 x 220 x 73 mmDynamic load rating 540 kN 585 kNMachining tolerances of journals p6 p6Machining tolerances of housing bores H7 H7Radial clearance 130...180 µm Clearance group C3FAG 64