When it comes to automotive performance, every component counts. This is especially true for the integrated hub unit, which helps keep your wheels attached to your vehicle, improves overall drivability and safety, and is critical to your anti-lock braking system (ABS) and the traction control system (TCS).
SKF has led the way in wheel end innovation since the invention of the automobile, pioneering the concept of the pre-assembled unitized hub, as well as the integration of sensors to improve passenger safety and enhance car functionality.
To put the evolution of the design of SKF hub bearing units into better perspective, let’s take a deeper dive into the company’s portfolio of high-quality solutions:
Taper Roller Bearings:
SKF offers a wide range of tapers with pressed steel cages, manufactured to rigorous quality standards in both metric and inch sizes. With low cross sections and precise contact angles, these wheel bearings are designed to accommodate axial and radial loads when mounted with proper clearance.
Hub Bearing Unit 1 (HBU1):
Based on a double row angular contact ball bearing, HBU1 is optimized for the special operating characteristics encountered on car wheel applications. The unit offers specific support the moment a load is applied to the bearing during cornering. The main components, an outer ring and two inner rings, are matched with the ball set to give the correct clearance. The cages for the two ball rows are made from glass fiber reinforced polyamide. HBU1 is greased and sealed for life. Used mainly for driven wheels, HBU1 is also found in integral drum designs on the non-driven wheels of smaller cars.
Hub Bearing Unit 2 (HBU2):
Designed with the experience gained with HBU1, HBU2 has an outer ring with an integral flange, replacing the function of a separate hub. The flanged outer ring is designed as a lightweight structural component and the outer ring raceways are induction hardened for optimal bearing performance. The flange is tough, with threaded holes or studs and a spigot to center and mount the brake and wheel. The dimensions of the flange and spigot are designed to customer requirements. HBU2 is typically used with a rotating outer ring for non-driven front or rear wheels.
Hub Bearing Unit 3 (HBU3):
The third-generation hub bearing units carry a flange for the wheel and brake rotor attachment and a second flange for fixing the unit to the suspension. This fully integrated system provides significant simplification in corner design and handling when compared with more traditional designs. The dynamic load carrying capacity is maximized by using a separate inner ring for the inboard ball row. This inner ring is mounted with an interference fit and the outer ring flange is bolted to the suspension. The rotating inner ring, with its tough flange, spigot and threaded holes or studs, is designed for mounting the brake and wheel. HBU3 is also greased and sealed for life and used for both driven and non-driven wheel applications.
X-Tracker:
The X-Tracker series, the latest generation of SKF hub bearings, brings car-like handling and comfort characteristics to high-performance, light-duty truck and SUV applications. The newest design consists of a double row angular contact ball bearing arrangement, in which the outboard row is at a higher diameter and contains more balls than the inner row. This unique design increases the bearing’s capacity while improving hub stiffness by 50% over a traditional tapered bearing unit. A stiffer hub provides many benefits:
o Allows the wheel to run truer during cornering and acceleration.
o Reduces deflection of the hub face and wheel, which provides better steering, handling, and vehicle dynamic behavior.
o Reduces brake wear and tear, which helps reduce brake warranty costs.
o Improves both NVH (noise/vibration/harness) characteristics and bearing performance.
o Provides designers and systems integrators an alternative to a tapered bearing unit, allowing them to improve overall vehicle performance.
Today, over 80 million cars and light trucks worldwide are riding on SKF wheel bearings and hub units – more than all other brands combined. Next time you’re on the market for a new hub unit, install with confidence using an SKF solution.