Hub bearing unit 3

A more compact new wave in the '80s

By the early 1980s, demand was still growing for ever-shrinking designs – automakers wanted even lighter, more compact, cost-effective components. The HBU3 offered it by incorporating a flange in the non-rotating bearing ring, and another flange in the rotating ring of the bearing. A small rotating inner ring was mounted on the rotating flanged inner ring to maximize carrying capacity. Today’s HBU3 is helping the industry hit several efficiency targets, reducing weight, noise, vibration, assembly and system costs all at once.

Driven and non-driven wheel applications for medium-big size cars

In the most common HBU3 application, the brake disc or drum and wheel are mounted to the rotating flange. This rotating flange is in many cases machined after bearing assembly, to achieve very low tolerances of lateral run-out, to contribute in lowering vibrations and noise during braking.

A fully integrated wheel bearing system

Hub Unit 3 features a double row angular contact ball bearing with matched rings and ball-sets to provide the required axial clearance or preload. Contact angles are optimized to provide specific preload and withstand specific wheel load condition

For the most recent HBU3 designs units, a post-assembly orbital forming provides the required axial preload when mounted on the vehicle – independently from the final vehicle assembly conditions.

Key features

  • Flanged rings designed as a lightweight structural component
  • Outer ring raceways are induction-hardened for bearing performance
  • Sealed with high performance, application-specific grease
  • Robust fixed and rotating flanges feature threaded holes or studs and a spigot to centre and mount brakes and wheels
  • Flanges can be coated to avoid galvanic corrosion with the mating components
  • Alternative designs are available for driven wheel applications
  • Available with ABS impulse ring mounted on the rotating ring

HBU3.2T for non-driven, light truck applications

The HBU3.2T is becoming the preferred choice for non-driven wheels applications for light trucks. Externally similar to an HBU3, the Hub Unit 3.2T features a double row angular contact tapered bearing. The HBU3.2T is a solution alternative to single tapered bearings, HBU1T in case of aluminium or light alloy knuckles, HBU2T and journals.
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