Quick replacement
January 1st 2008

Split roller bearings mean that bearing failures can be rectified quickly saving thousands in downtime costs

The ability of mechanical failures to completely shut down sugar refineries during the busiest time of the year was demonstrated recently at one Norfolk facility, causing 30,000 tonnes of beet to be transferred to other factories in the adjacent area while the problem was sorted out.

Unfortunately, even with planned maintenance schedules, unexpected mechanical problems do occur from time to time, so the emphasis has to be on using equipment that, once failed, is relatively quick and easy to return to service. As industry professionals know this is much easier said than done, with the complicated power transmission systems that drive equipment such as conveyor and tipper drives, crushing plant, feeders and Bagasse (waste sugar cane fibre) pump drives. However, there is one component area of power transmission systems that can make a real difference to the production time lost to failures, and this is the use of split roller bearings (SRB) instead of solid bearing types. Split Roller Bearings can be replaced quickly if there is a problem; usually in about 1/10 of the time of that required for solid bearings.

Despite this advantage, solid bearings still predominate, largely because they are initially cheaper to purchase than an equivalent sized SRB split roller bearing.

This situation militates against the longer term view of overall lifetime costs, which is now becoming the norm across most continuous process industries. In other process sectors that are experiencing similar cost down pressures to sugar processing, companies are increasingly waking up to the fact that to achieve performance gains, and realise the full potential of their existing assets, they must achieve improved production efficiencies.

However, to achieve these efficiencies downtime must be minimised, which in turn, means that a whole new approach of adopting components and equipment that might cost slightly more initially, but are much more cost effective over the longer term.

This is where SRB split roller bearings come into the equation. In addition to significantly cutting downtime, they offer a host of additional advantages from the technical, economic and pure design point of views.

The simplicity of fitting a SRB split roller bearing, compared to a solid bearing, is an important factor in its longevity. Unlike solid bearings, SRB split bearings are totally split to the shaft, a design that both simplifies and expedites installation and cuts installation downtime by up to 90%.

There is no need to lift the shaft, or obtain access to the shaft ends, therefore expensive and awkward to handle lifting equipment is not required. This intrinsic feature is extremely valuable for all applications, and especially regarding large machines, where sheer size and weight can be a barrier to fast and effective servicing. It allows for much faster bearing replacement, which can save productivity focussed businesses a lot of money in costly downtime.

In addition to being easier to fit, inspect and maintain than solid bearings, SRB split bearings also provide superior sealing arrangements, which means longer bearing life with greatly reduced levels of maintenance, especially important for sugar processing applications. SRB split bearings are available with seal designs that allow them to operate completely submerged, totally excluding water and contaminants from the bearing. This is achieved via an arrangement of two lip seals with garter springs & retaining plates, and a central positive grease feed between each seal. The positive action of the grease purge between the two high performance seals offers consistent & reliable long-term operation.

The example in Table 1 illustrates the savings in Downtime that can be accrued using SRB split bearings. The data is taken from an actual example, where solid bearings were replaced with SRB split bearings due to the costs that were being incurred as a result of extended times for bearing installation and replacement. As the table shows, the initial purchase cost for the SRB split bearings are higher than those of the solid bearing. However, when the total replacement costs are considered, including labour and production losses, the position is reversed with the total overall cost for the SRB split bearing being 80% lower than that of the solid bearing.