Split bearings provide reduced maintenance costs

Pilbara Iron has achieved significant cost savings by replacing a standard spherical roller bearing on the drive shaft of a bucket wheel excavator with a split roller bearing from Schaeffler.

Pilbara Iron, a member of the Rio Tinto Group, operates mining, rail and port facilities.

The company operates two shipping terminals in Dampier, Australia.

Each terminal is equipped with train unloaders, iron ore storage and blending facilities, as well as ship loaders.

A bearing on the main drive of a bucket wheel excavator at Dampier had to be replaced recently.

The bearing - an FAG standard spherical roller bearing from Schaeffler - was difficult to access and required the transmission shaft be dismounted first.

This meant replacing the bearing was a lengthy, labour-intensive process.

Pilbara Iron estimates that it loses 72 hours of production downtime each time this type of bearing needs replacing.

Following a recommendation from Schaeffler Australia, Pilbara Iron decided to replace the standard spherical roller bearings with FAG split spherical roller bearings.

These bearings have a diameter of 620mm and weigh 210kg.

Due to their split design, the bearings can be mounted into the existing housing without having to remove the transmission shaft.

When the new bearings were actually fitted to the main drive on the bucket wheel excavator, production losses were cut by 50 per cent, while maintenance labour costs were also significantly reduced.

Although the cost of purchasing a split spherical roller bearing is several times higher than a conventional version, the potential for cost savings over the life of the bearing is said to be substantial.

At Pilbara Iron, the cost benefit amounted to EUR27,500 (GBP25,274) for each bearing replacement.

The company also benefits from long-term savings in maintenance costs, since the split spherical roller bearings enable faster and simple bearing replacement.

With split spherical roller bearings, the inner ring, outer ring and cage assembly are split.

A cylindrical bore provides direct mounting onto the shaft.

These bearings typically offer high thrust load capability and dynamically compensate for any misalignment.

With the FAG range of split spherical roller bearings from Schaeffler UK, the outside diameter, outer ring width and shaft seat diameter are identical to the dimensions of the standard spherical roller bearings range.

This means customers can replace solid bearings with split versions with an adapter sleeve.

Mounting of split bearings normally leads to a reduction of machinery downtime and maintenance costs, particularly in those industries where the value of capital equipment is normally high, including mining, quarrying and mineral processing.

In many cases, split bearings can also reduce the cost of new designs, because the bearings simplify the assembly process and mounting procedure.

As well as bucket wheel excavators, split spherical roller bearings can also be found on winch drums, screw conveyors, mixers and stirrers, mills, crushers, rotary kilns, fans and blowers, drive and line shafts, which all require regular maintenance, repair and overhaul.

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