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Schaeffler has developed a range of bearing solutions that are helping vehicle manufacturers to produce more compact, lighter vehicles, with improved fuel consumption and reduced CO2 emissions.

The latest of these innovations is the FAG wheel bearing, said to be more compact and 10 per cent lighter than its predecessor.

The 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 per cent 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 lighter and can be mounted clearance-free.

Driving characteristics are improved and automotive manufacturers benefit from a simple mounting process and the associated cost reductions.

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.

The FAG wheel bearing with spur gear teeth is 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.

Another bearing solution from Schaeffler is the INA lightweight balancer shaft and rolling bearing assembly.

This is currently being used on the Mercedes-Benz OM 651, a 2.2l, four-cylinder diesel engine that produces up to 204ps and 500Nm torque.

The weight of the INA balancer shaft and bearing assembly are optimised in order to improve engine efficiency and reduce overall fuel consumption.

By replacing conventional plain bearings on the balancer shaft with rolling bearings, friction is reduced.

Using needle-roller bearings with a raceway directly on the shaft reduces friction by up to 50 per cent over the whole speed range.

At the development stage, by analysing engine-load conditions, Schaeffler was able to optimise weight distribution.

This enabled the width of the bearing to be reduced, which meant that the weight of the shaft could be cut by more than a third.

This equates to an engine-weight saving of 0.75kg.

When designing the complete drive train for the OM 651, Mercedes was then able to utilise this reduced shaft rotational inertia.

The lower mass moment of inertia reduces the load in the power train, improving the acoustic characteristics.

In addition, the narrower raceway improves the oil-mist supply to the rolling bearings, enabling a simpler system design without oil-feed holes, reducing manufacturing costs.

The engine requires a lower throughput of oil, so the oil pump can also be made smaller.

All of these technical improvements meant that engine fuel savings of around 0.5 to one per cent were achieved.

With the global market for four-cylinder engines standing at almost 50 million systems a year, the INA lightweight balancer shaft assembly offers potential for reducing engine fuel consumption and emissions.

Based on an average reduction in fuel consumption of one per cent over the life of an engine and calculated for a vehicle mileage of 250,000km, this would lead to approximately 175l of fuel savings.

Even if only 25 per cent of all four-cylinder engines were fitted with INA lightweight balancer shaft assemblies, this would still reduce harmful CO2 emissions by around six million tonnes a year.

The larger the vehicle, the greater the savings.

Trucks, SUVs and light vans are also benefiting from innovative bearing solutions.

By replacing line contact associated with conventional tapered roller wheel bearings with a design based on point contact using ball bearings, Schaeffler has developed a twin-tandem wheel-bearing unit, which reduces friction by around 50 per cent over conventional tapered-roller wheel bearings.

This equates to a 1.5 per cent reduction in fuel consumption.

The twin-tandem design is based on replacing the rows of tapered roller bearings with two rows of ball bearings in each case.

A double-row tapered roller bearing therefore becomes a four-row ball bearing.

Replacing the line contact of the tapered rollers with the point contact of the balls eliminates rib friction and reduces overall friction by 50 per cent.

The twin-tandem bearing also has a lower operating temperature compared to conventional tapered roller units, therefore improving the service life of the lubricants.

Cornering stiffness is also increased.

Schaeffler has also considered interchangeability of the twin tandem with conventional tapered units.

The twin tandem is designed to cater for the use of sensors (such as ABS sensors) and installation in the wheel carrier is identical for conventional tapered roller wheel bearings.

Assuming a vehicle emits 300g/km of CO2 over a distance travelled of 15,000km a year, the reduction in CO2 emissions resulting from the twin-tandem unit will be 67.5kg per year, per vehicle.

Fuel consumption is also reduced by 1.5 per cent, giving a reduction of 40l/year for an average light truck travelling 15,000km a year.

A collaborative development between Schaeffler and Fiat Powertrain has resulted in a new engine system, said to be the world’s first fully variable hydraulic valve control system, which reduces vehicle fuel consumption and cuts CO2 emissions by up to 25 per cent.

Uniair is a fully variable hydraulic valve control system that will make its debut on Fiat’s Alfa Mito 1.4 Multiair.

This is the first vehicle within the Fiat Group to be equipped with this technology.

As well as offering car manufacturers a more compact valve-control system, Uniair will help the automotive industry meet future CO2 emissions targets for passenger cars.

Uniair provides improvements in startup, part load and acceleration behaviour of the vehicle.

During the engine warm-up phase, for example, hydrocarbon (HC) emissions are up to 40 per cent less and nitrogen oxide (NOx) is reduced by up to 60 per cent.

In addition, Uniair offers a greatly improved driving experience, through more power, higher engine torques and optimised engine response.

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