Bearing solutions cut vehicle fuel consumption
The Schaeffler Group has developed a range of bearing solutions that are helping vehicle manufacturers produce more compact, lighter vehicles, with improved fuel consumption and reduced CO2 emissions.
The latest of these innovations is the FAG wheel bearing, which Schaeffler says is more compact and 10% lighter than its predecessor. The new bearing also offers simplified mounting via a self-centring, axial spur gear teeth design.
First developed in 2004, the FAG wheel bearing has since moved into series production, with BMW already using the unit on its new X1 model. A reduction in weight of 10% typically amounts to an overall weight reduction of 1kg for a four wheel vehicle.
With a spur gear teeth design, in which the wheel bearing and axle journal are connected axially rather than radially, the bearing module is designed to be lighter and can be mounted clearance free.
Previously, the gear teeth of the axle journal of the input shaft were pushed axially into the wheel bearing. Here, the drive torque was transferred via longitudinal gear teeth. This mounting method has proven itself over many years; however, it has a number of disadvantages. The relatively solid, heavy component requires a certain amount of clearance to enable easy mounting. Also, loads that occur during vehicle operation can lead to the assembly becoming loose, resulting in loss of comfort and higher noise levels, as well as possible failure of the bearing.
Up to now, the solution has been to reduce the radial clearance to zero in the design phase. However, this requires the use of complex, costly mounting technology.
The FAG wheel bearing with spur gear teeth is better equipped to deal with the loads that occur during vehicle operation. The spur gear teeth ensure positive connection between the wheel bearing carrier and the input shaft, which simplifies mounting considerably. The self centring axial gear teeth are simply placed on the axle journal and fixed in place by using a central screw. Unlike radial gear teeth, this mounting procedure does not require significant force. The bearing remains clearance free, but securely held in place during vehicle operation.
Having four lighter wheel bearings on the vehicle reduces the unsprung masses, which improves the driving characteristics and contributes to a reduction in CO2 emissions.
