Split bearings specialist OE Bearings has developed the SNQ and SDQ ranges of angled split plummer block bearing supports, which are fully interchangeable with standard SN and SD series plummer blocks.
The angled split plummer block bearing supports are used on the split cylindrical roller bearings that OE Bearings distributes in Southern Africa on behalf of UK-based manu- facturer Revolvo.
OE Bearings’ first development on plummer blocks was the design and development of interchangeable SN and SD split plummer block bearing supports in 2001, which were, before then, not compatible to be interchanged with standard SN and SD series plummer blocks, owing to differences in bolt-hole spacing and the base-to-centre height.
In most instances where a standard solid bearing had to be replaced with a split bearing, adjustments, including modifications to the original steelwork, had to be made, explains OE Bearings MD Warwick Steinhobel.
By using a split bearing instead of a plummer block, the time it takes to assemble the bearing is significantly reduced. “Plummer blocks take about eight hours to install, while it takes only one hour to install the split roller bearing (SRB),” he says.
The SRBs are assembled using Allen keys and feature components that are matched by number and have grooves on one side for the easy alignment of parts.
The SRB can also be inspected, unlike the spherical roller bearings in plummer blocks. To do this, the bearing is jacked up and the support cap and bearing cage removed to enable inspection.
Further, the SRBs 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 there is any misalignment, spherical surfaces between the bearing housing and the bearing housing support unit enable the housing to move with the shaft, which allows for the seal to remain concentric to the shaft and prevent the seal from being stressed to the point where it allows contaminants to enter.
In addition to this sealing mechanism, OE Bearings, in conjunction with Revolvo, has designed and developed an additional sealing mechanism, the Vee Ring seal. This seal is used specifically with split bearings to dramatically improve the sealing ability of the bearing.
The Vee Ring wraps around the bearing shaft and is held together using a cable tie. This seal ensures that the bearing lasts longer and that it maintains lubrication in the bearing housing.
Steinhobel says the Vee Ring was conceptualised in March and was developed over five months by Revolvo and delivered to OE Bearings in August.
Further research and development on the Vee Rings is currently under way and involves testing for water ingress into the bearing at different speeds.
OE Bearings will introduce the Vee Ring onto the market in the next three months, once the tests have been concluded.
Steinhobel says bearings, in general, seldom reach the end of their design life and fail before the estimated period, owing to incorrect fitting, lack of maintenance and the ingress of contaminants.
“These are the problems OE Bearings is dealing with through its design developments and testing,” he says.
The testing of OE Bearings’ products in South Africa is done in conjunction with the Revolvo factory.
The OE Bearings test rig, designed and developed in 2006 by the company to test and carefully monitor its product developments, tests bearings in excess of their normal operating speeds and their dynamic, static and axial capacities until they are about to fail. This enables the company to gain data on the limits of a product’s capacities.
The test rig, powered by a three-phase electric motor with variable speed, is equipped to test three different bearing shaft sizes, with diameters of 110 mm, 135 mm and 170 mm.
Steinhobel says OE Bearings developed the test rig to ensure that its products are suitable for the applications to which they are supplied.
Further, OE Bearings also conducts finite element analysis on the bearings, with a computer-aided design programme.
“Our SRB products are increasingly being specified by clients to the point that they have become the market standard. I predict that the angled split plummer block bearing supports and the Vee Ring will become the market standard in future,” states Steinhobel.
Owing to the ease and shorter time of installation, companies such as diamond miner De Beers, platinum miners Impala Platinum and Lonmin, diversified miners Anglo American and Xstrata, State-owned power utility Eskom, as well as State-owned freight logistics group Transnet, have specified OE Bearings’ products.
OE Bearings tells Engineering News that it received a R500 000 order from Transnet Port Terminals (TPT) in August for a SRB for use on a bucket wheel at the freight logistics group’s Saldanha iron-ore export port.
Steinhobel says that, owing to the development of numerous new iron-ore mines in the Northern Cape, which will need to export their product from Saldanha, the pressure on the port to have 100% availability has become very high.
The 500-mm-diameter SRB for TPT is being manufactured from SKF-grade steel by Revolvo, in the UK, for delivery in January 2013.
Steinhobel is excited about the contract as he believes that once this installation has proved successful, it will lead to many more bearing changes on bucket wheels at iron-ore mines.
He notes that a major advan- tage of fitting an SRB is that the conventional replacement time of a bearing, which can take up to four weeks to replace, can be reduced to hours for a split bearing.
Further, he believes the market share for SRBs will increase owing to the decreasing skills base and the simplicity of the bearing.
The large number of plummer blocks used in industrial applications today, such as in paper and steel mills, power station conveyors and mine-ventila- tion fans, and the opportunity for OE Bearings to replace these bearings with split bearings, allows for long-term growth potential for the company, says Steinhobel.
“Our development work is paying dividends and the more product development we undertake to improve our bearings, the more popular and better designed the products become,” he says.
Provided that the South African mining industry does not collapse, as it is a big part of the economy, OE Bearings expects to see good sales prospects in South Africa and in the rest of Africa.