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Drivetrain

Hub & Wheel Bearing Technology

History

Prior to the 1970s, wheel bearings and associated components, such as seals and hub nuts, were always sold as separate items.

 

Sometimes the repairer would have to visit a bearing distributor to obtain the individual bearings and then go to the vehicle main dealer to get the replacement seals and other items.

As this could be both a frustrating and time consuming exercise, a number of leading aftermarket suppliers approached the individual bearing manufacturers and started to supply ‘Wheel Bearing Kits’ where, for example, two different bearings and one or two seals were packaged together and sold as a complete ‘Repair Kit’ for one wheel.

At a time when there were still many rear wheel drive models on the road (the Ford Escort being a prime example), most front wheel kits would comprise the two different size Tapered Roller Bearings and one or two seals. The inclusion of a new split pin helped when refitting the castellated hub nut and for convenience a sachet or tube of the correct specification grease may also have been included. Rear kits would often just comprise a single row ball bearing together with a new retaining collar.

More elaborate kits for the British Motor Corporation (BMC) front wheel drive models also became available with pairs of angular contact ball bearings and a spacer but even so, the number of different part numbers available was initially quite small and limited to about 100 or 150 references. At this time, the kits for models such as the Ford Escort, Cortina and BMC Mini and Allegro represented a very large percentage of the market.

Market changes

Over the next 30 years or so the UK car parc changed dramatically, with ever growing numbers of European and Far Eastern car manufacturers increasing market share and three Japanese companies actually building manufacturing plants here in the UK. Consequently, wheel bearing kit ranges became ever more diverse. This is clearly demonstrated by the current First Line range, which now includes nearly 1000 part numbers.

Other suppliers have also caught on to the growing demands placed on the wheel bearing market

The company subscribe to the philosophy that in order to perform the best possible repair from a technical point of view, it is an absolute must that as well as replacing the faulty part itself, the components in the immediate environment should be checked and replaced also.  Therefore, Ruville contributes to this by developing a spare parts programme which offers intelligent and tailor-made repair kit applications as well as individual components to perfectly match each repair requirement.  This led to the development of their wheel bearing module range.  These kits incorporate the wheel bearing or wheel bearing module, the fixture elements and the necessary seals.

Product Changes

The product has had to move with the times.  Single row bearings have been replaced largely by double-row bearings and bolt on hub units. These units are more suitable for front wheel drive applications and can have either ball or tapered roller bearings. They are much easier to fit and other advantages include a built in pre-load setting.  Therefore, no spacer is required; they are pre-greased and have an integral high performance seal. Whilst many vehicles are fitted with double row angular contact ball bearing units, some heavier duty applications use tapered roller bearings which have a greater load capacity.

Further developments include double row units with outer and/or inner mounting flanges. Some of the outer flange units are supplied complete with the wheel studs in situ and, when used for front wheel drive applications, will have a splined bore to accept the drive shaft.

When sourcing products, First Line and Ruville make no compromise when it comes to quality and as such, each part is sourced to OE specification.  Ruville’s wheel bearings and the hubs themselves are made of high quality advanced roller bearing steel. They are equipped with an optimised sealing system specifically integrated into the unit, as well as specialised race ways (running tracks) and grease for high speed of rotation.

ABS and ‘ASB’ applications

ABS or anti-lock braking systems, whilst initially only fitted to expensive luxury models, are now standard equipment on all but very basic vehicles. As ABS works by measuring the rotational speed at each wheel, some form of speed sensing device is required. This was often achieved by fitting a notched ring at each wheel, sometimes on the constant velocity joint on the front of four wheel drive models or on the bearing hub unit. Some hub units have an internal electronic sensing device within the hub unit with an external plug to connect the sensor. This type of hub unit was used extensively on Vauxhall models.  All new generation hubs supplied by Ruville are prepared with multi pole encoder technology in order to obtain a clear signal for ABS, Electronic Stability Programs (ESP) and Electronic Traction Control systems.

Ruville has had to revise and adapt their range to meet the need for a speed sensing mechanism.  Their 1st generation and 1T generation are both compact units with a two rowed ball bearing and a taper roller bearing respectively. All bearings and hubs of this generation are prepared with life time grease filling and may be equipped with an integrated multi pole encoder ring. The 2nd generation combine the advantages of the first generation with integrated hubs, are safeguarded with an innovated locking ring and equipped with an orbital head.  Since the introduction of the 2nd generation, Ruville have guaranteed the correct bearing clearance with the integrated orbital forming head.   The 3rd generation comprises an integrated unit with two flanges and an orbital formed head, including a magnetic multi pole encoder ring and sensor.

First Line, not a supplier to stand still, has also kept track of developments in this sector.  One of First Lines’ Bearing Kit Partners is SNR, a French bearing manufacturer who, until recently, was part of the Renault organisation and is a major OEM bearing supplier. In 1997 SNR put into production a new concept in wheel bearings which they called ASB or Active Sensor Bearings. An ASB bearing is fitted with an integrated magnetic seal that permits remarkably accurate and reliable measurement of wheel speed rotation for operation of ABS, ESP and Electronic Traction Control. The ASB system is protected by many patents and was initially used on Renault Laguna models. Since then other vehicle manufacturers including Alfa Romeo, BMW, Citroen, Honda, Peugeot and VW Audi Group have fitted ASB bearings or hub units.  SNR have licensed several other bearing manufacturers to use the ASB technology and more than 80% of new vehicles will now be using this system.

Whether they are First Line kits or Ruville modules, the aim is to ensure that all parts for assembly are in one box, thereby minimising downtime in the workshop.  Simple and quick assembly is a hallmark of these products.

Future Developments
 

A number of new vehicle models (notably some Renault and Peugeot/Citroen models) are now being fitted with rear discs where the bearing cannot be successfully replaced without risking damage to the housing or ABS/ASB sensor, which in some cases is fitted onto the disc itself. The First Line Bearing Kit Range already includes an ever growing range of disc assemblies.

First Line source Bearings and Hub Units from all major mainstream bearing manufacturers including Koyo, NSK-RHP, NTN, SKF, SNR and Timken and is well placed to keep pace with all future technological developments. SNR are already well advanced with a new generation of ASB unit which is fitted with outer ring load sensor gauges. These units allow advanced chassis control and powertrain management.

Ruville, as part of the Schaeffler Group Automotive Aftermarket are also well placed to be at the forefront of new product developments.  In particular, the Ruville engineers can benefit from the technical know-how and experience that has been built within the Schaeffler Group.

From this year, Ruville will be offering wheel bearing hubs with axial spline; a most recent innovation in the wheel bearing product group.

The Bearing Kit Market is becoming highly technical and many of the hub units are high value products. Both First Line and Ruville, are committed to supporting all of these new developments together with clear and concise cataloguing and the regular release of new to range references.

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