The Design of Rolling Bearing Mountings

50Axle box roller bearingsaccording to AAR standard*) and modified typesThe FAG TAROL unit according to AAR standards isa compact bearing unit with a double row tapered rollerbearing as the main component. Seals at both sidesof the bearing, accessories and the grease filling makethe FAG TAROL a ready-to-mount unit. Neither isthe adjustment of the bearing clearance required. Theso-called NFL design (no field lubrication) is consideredstandard today. These TAROL units are no longerrelubricated during operation. The bearing grease isonly renewed during a main inspection.FAG use two types of seals: the rubbing radial shaft seal(fig. a) corresponds to the design used by AAR. Thenon-rubbing lamellar seal ring (fig. b) was developedby FAG and tested and approved by AAR.TAROL units do not have to be mounted into a housing.An adapter is attached between the TAROL unitand the bogie frame to transmit the loads and supportthe bearing cup on the loaded part of the circumference.FAG supply NARROW and WIDE adapters accordingto the AAR standards as well as special adapters designedfor the particular cases of application.a: Rubbing radial shaft sealAAR has stipulated the admissible loads for the varioussizes of TAROL units.Components of the FAG tapered roller bearing unitTAROL1 Locking plate2 Cap screw3 End cap4 Bearing cup5 Bearing cone with roller set6 Spacer7 Seal wear ring8 Seal9 Backing ringb: Non-rubbing lamellar sealFAG also supply TAROL units in metric dimensions.They (fig. c) have narrower tapered roller bearings andsmaller sealing and retaining components than theAAR design. The relevant journals are also shorter resultingin lower bending stresses with the same shaftdiameter than in the case of the AAR arrangement.Higher wheel loads are therefore admissible.21378 5 6 4 7 8 950: TAROL unitswith a double-row tapered roller bearing*) Association of American Railroadsc: TAROL units in metric dimensions and with short journal(SK design)FAG 72