SCHWEINFURT, Germany, May 15 - An approximate 10 percent reduction in weight and a considerably simplified mounting procedure (compared with conventional radial splines) are the most significant advantages of the new FAG wheel bearing concept that is preloaded by means of axial splines in the axle journal. The use of the orbitally formed shoulder as a carrier for clearance-free axial gear teeth enables this wheel bearing module to be produced economically.
Low Weight, Economical to Fit
Traditionally, drive torque is transmitted between the wheel bearing and the axle journal by means of radial splines. The teeth usually have a certain amount of clearance in order to make mounting easier. Loads that occur in day-to-day driving conditions mean that there is a risk that the assembly constantly loosens beyond the normal mounting clearance, resulting in everything from loss in comfort to unpleasant noises to bearing failure. Until now, the only solution was to reduce the radial clearance to zero in the design phase, which requires the use of expensive and complex mounting technology.
However, the new FAG wheel bearing module with axial splines is appealing due to its simple mounting methods. Self-centering axial gear teeth are placed on the axle journal and fixed in placed by means of a central screw. The bearing remains completely clearance-free in the gear teeth during operation. Regardless of whether the vehicle travels 1,000 or 100,000 miles, the bearing won't budge during the entire operating life. Additionally, the system weighs approximately 10 percent less than a conventional bearing -- causing a weight savings of more than one kilogram.
The Orbitally Formed Shoulder Makes Everything Possible
The concept behind axial splines is not new. In fact, the cost-effective production of this design idea first became a reality when an orbitally formed shoulder was used as a carrier for the gear teeth. In 1989, FAG axially fixed the bearing inner ring with the orbitally formed shoulder to eliminate the screw fixing that was common at that time (this was initially designed for wheel bearings in the Seat Marbella and later in BMW's mid-class sedans).
In the new wheel bearing concept, the axial splines are applied onto the orbitally formed shoulder by high-precision cold forming. A comprehensive series of tests has shown that the torque transmission with the axial splines is considerably higher compared with radial splines, mainly due to the larger diameter of the pitch circle of the gear teeth.
Schaeffler KG engineers have been working on this new design since 2004. Start of volume production for all-wheel drive mid- and upper-class sedans has already been scheduled for next year. The advantages in terms of cost-effectiveness and environmental aspects have already been recognized.
The Schaeffler Group
The Schaeffler Group and its 66,000 employees at more than 180 locations worldwide generates group sales of around 8.9 billion Euros (FY 2007) and ranks amongst the leading rolling bearing manufacturers and suppliers to the automotive industry worldwide. The group of companies is made up of Schaeffler KG (Herzogenaurach) and the global brands INA and FAG, as well as the LuK Group (Buehl/Baden).
To serve the North American automotive market, the Schaeffler Group operates a 78,000-square-foot North American Automotive Tech Center in Troy, Mich. This facility employs 165 engineers and technicians and houses a 30,000-square-foot, state-of-the-art test lab outfitted with multiple test cells capable of performing test simulations for engine and engine components. Schaeffler Group Automotive has headquarters in Fort Mill, S.C. and manufacturing facilities in South Carolina, Missouri, Ohio and Ontario, Canada.
Source: The Schaeffler Group
Richard Neilson of Schaeffler Group USA Inc.,
both of Bianchi Public Relations,
+1-248-269-1122 for The Schaeffler Group