Split bearings specialist OE Bearings has completed a contract to supply Pretoria Portland Cement’s (PPC’s) Zimbabwe factory with split roller bearings.
The contract, which was completed earlier this year and was valued at R155 000, involved split roller bearings installations on a number of the Colleen Bawn plant’s facilities.

The Colleen Bawn plant, near Bulawayo, supplies cement clinker to PPC’s South African arm.

OE Bearings’ operations director Dennis Cooney says that Zimbabwean industry offers great potential for future business.

He adds that OE Bearings is pursuing a number of business opportunities in the country’s gold mines.

OE Bearings is the South African importer of UK-based bearings solutions provider Revolvo’s full Split Roller Bearings (SRB) range of split cylindrical roller bearings.

SRB bearings have been installed on a coal firing fan at the Zimbabwean PPC factory. The bearings have to withstand high pressure and high speed as the fan pumps pulverised coal dust into a kiln to fuel the firing of cement clinker.

The factory has two such fans. However, one is used as a backup to the primary fan in case the primary’s bearings fail. Therefore, OE Bearings fitted 85-mm SRB bearings to the primary fan and has supplied PPC with another set for the secondary fan.

SRB bearings have also been supplied for the factory’s furnace extraction fans. These large fans extract the superheated air from the kiln and pass it through a set of filters before it is released into the atmosphere.

The 150-mm and 160-mm SRB bearings need to withstand extremely hot temperatures and operate at high speed and high pressure.

The benefit of using split bearings over traditional bearings lies in how quickly the split bearings can be replaced and, con- sequently, the reduction of down time, says OE Bearings director Warwick Steinhobel.

He says the SRB products that OE Bearings offers are priced higher than equivalent plumber block units; however, the down time costs associated with the repair and maintenance of split bearings are significantly lower.

He adds that OE Bearings has worked closely with Revolvo, in the UK. Together they developed a range of split roller bearings that have the same dimensions as traditional plumber block bearings, a split bearings specification that had up until that time been very difficult to source.
He attributes OE Bearings’ success in recent years to its technical experience and the ease with which its products can be installed.

It is very easy to assemble SRB bearings, says OE Bearings technical consultant Leon Van den Berg. Bearings components that fit together have corresponding numbers and certain mating surfaces have corresponding pins and holes to prevent incorrect assembly.

No special tools are needed to assemble the bearings because only Allen keys are required.

The cage of an SRB bearing is made of brass. Van den Berg says that the bearing’s cage is the most important component because it holds the rollers in place and is the component most likely to fail first. He says brass is one of the best materials from which to manufacture a cage as it can withstand the vibrations and shocks associated with the loads placed on bearings.

SRB bearings are designed in such a way that the bearing housing and shaft cannot become misaligned, which would allow dirt and contaminants into the bearing, damaging it and shortening its life.

If the shaft moves off its axis, spherical surfaces between the bearing housing and the bearing housing support unit allow the housing to move with the shaft, allowing the seal to remain concentric to the shaft, preventing the seal being stressed to the point where it allows contaminants to enter.

Applications for SRB bearings include air movement, cement production, conveyor systems, power gener- ation, quarrying, manufacturing, and sugar and timber production.

The SRB offering comprises light, medium and heavy bearings, ranging from 35 mm to 600 mm and can be specified with a pillow block, flange, hanger or take-up support unit.

Cages are equipped with profiled rollers that are shaped to prevent load stress from acting only on the edges of the roller by spreading the load along the roller’s entire length, which extends the life of the bearings.
SRB bearings’ supports and housings are manufactured from grade 250 cast iron, which makes them stronger and less likely to break if excessively loaded.

Steinhobel says that although the SRB range is imported, OE Bearings has the facilities to manufacture a full bearings solution should the need arise.

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