The Design of Rolling Bearing Mountings

2 Traction motor for electric commuter trainsThe bearing at the opposite end is lubricated with alithium soap base grease of NLGI penetration class 3(FAG rolling bearing grease Arcanol L71V).The bearings should be relubricated after 400,000 kilometersor five years, respectively. Multiple labyrinthsprevent contaminants from penetrating into the bearings.Operating dataSelf-ventilated converter current motor, permanentpower 200 kW at a speed of 1,820 min –1 (drivingspeed 72 km/h), maximum speed 3,030 min –1 (maximumdriving speed 120 km/h), one-end drive withherringbone gear pinion.Bearing selection, dimensioningThe operating mode of commuter train motor vehiclesis characterized by the short distances between stops.The periodic operating conditions – starting, driving,braking – can be recorded on an operating graph representingthe motor torque versus the driving time.The cubic mean of the motor torque and an averagespeed, which is also determined from the operatinggraph, form the basis for the rolling bearing analysis.The mean torque is about 90 % of the torque at constantpower.The bearing loads are calculated as for traction motorsfor standard-gauge locomotives (example 1). They aremade up of the reaction loads resulting from the gearforce on the driving pinion and a theoretical radialload which takes into account the rotor weight, themagnetic pull, unbalanced loads and rail shocks. Thistheoretical radial load applied at the rotor centre ofgravity is calculated by multiplying the rotor weight bythe supplementary factor f z = 2. The value 2 takes intoaccount the relatively rigid motor suspension.An overhung pinion provides the drive. At the pinionend a cylindrical roller bearing FAG NU320E.M1.P64.F1is mounted as the floating bearing. At the commutatorend a deep groove ball bearing FAG 6318M.P64.J20Avery safely accommodates the thrust load resultingfrom the 7° helical gearing of the pinion, even at relativelyhigh speeds.FAG 8