The reliability of trucks depends to a very great extent on the front and rear hub bearing arrangements. Presently the most common solution for these commercial vehicles is the application of two single-row tapered roller bearings adjusted to a certain clearance. A new advanced Unit Concept offers economical improvements and technical advantages by the drastic reduction of the number of components, simplification of wheel bearing assembly, facilitation of service and brake inspection, as well as increased reliability of the bearing arrangement.
Truck Hub Units are double-row tapered roller bearings with separate cones held together by a retention ring and assembled in a one-piece outer ring. The design of Truck Hub Units with integral flanges on the outer rings mainly for non-driven front wheel applications are a further logical step of development. The flanged solution incorporates the function of the wheel hubs for centering the wheels and brake drums. Because of the reduced distance between the pressure or loading centers of the equally-sized Unit cones compared to previous conventional arrangements, specially developed roller track profiles are used to guarantee high bearing life even under the severe misalignment conditions caused during heavy cornering. In order to avoid, any risk of inaccurate setting during mounting, the required mounted axial clearance is predetermined for a specific application. FEM calculations are applied to optimize the strength and weight of the Truck Hub Units with integral flanges.
The advantages of the “Truck Hub Unit Concept” are: Accurate pre-adjustment, reduced risk of contamination from initial assembly and service, the possible integration of sealing devices and the reduction of the number of total wheel components resulting in considerable decrease of assembly time as well as potential cost savings. Functional tests on laboratory simulation rigs and actual field tests in heavy trucks have demonstrated the efficiency of the new wheel bearing concept.