The operating mode of commuter train motor vehicles is characterized by the short distances between stops.

 The periodic operating conditions – starting, driving, braking – can be recorded on an operating graph representing the motor torque versus the driving time. The cubic mean of the motor torque and an average speed, which is also determined from the operating graph taper roller bearing, form the basis for the rolling bearing analysis. The mean torque is about 90 % of the torque at constant power. The bearing loads are calculated as for traction motors for standard-gauge locomotives (example 1). They are made up of the reaction loads resulting from the gear force on the driving pinion and a theoretical radial load which takes into account the rotor weight, the magnetic pull, unbalanced loads and rail shocks. This theoretical radial load applied at the rotor centre of gravity is calculated by multiplying the rotor weight by the supplementary factor fz = 2. The value 2 takes into account the relatively rigid motor suspension. 

An overhung pinion provides the drive. At the pinion end a cylindrical roller bearing FAG NU320E.M1.P64.F1 is mounted as the floating bearing. At the commutator end a deep groove ball bearing FAG 6318M.P64.J20A very safely accommodates the thrust load resulting from the 7° helical gearing of the pinion, even at relatively high speeds spherical roller thrust bearing. Suffixes E Maximum capacity M, M1 Machined brass cage, rolling element riding P64 Tolerance class P6; radial clearance C4 F1 FAG manufacturing and inspection specification for cylindrical roller bearings in traction motors which takes into account, among others backing bearings, the requirements of DIN 43283 "Cylindrical roller bearings for electric traction". J20A Current insulation on the outer ring O double taper roller bearing.D. Machining tolerances For good support of the bearing rings, tight fits are provided: Cylindrical roller bearing: Shaft to n5; end cap to M6 Deep groove 

ball bearing: Shaft to m5; end cap to K6 Bearing clearance The tight fits and the high temperature due to the relatively high operating speed require an increased radial clearance C4 for the cylindrical roller bearing and the deep groove ball bearing. Lubrication, sealing The bearings are lubricated with FAG rolling bearing grease Arcanol L71V as for all traction motors. Relubrication is possible, and a grease valve is provided to protect against overlubrication. Experience shows that relubrication intervals of 250,000 km or 5 years provide optimum life. The bearings are sealed on both sides by multiple labyrinths (axially arranged passages)