Making the right choice!

Published:  06 May, 2015

Many businesses are focusing on reducing production costs, which includes maintenance time and lost production due to both routine and unplanned down time. By looking to make long-term improvements, most production operations should certainly consider the total cost of ownership (TCO) as well as the short term benefits of reducing maintenance time where possible. In situations where large pieces of rotating equipment are in use, these savings can be achieved by introducing SRB split roller bearings. PWE reports.

Unlike solid bearings, SRB split roller bearings are totally split to the shaft; a design that both simplifies and expedites installation and significantly cuts downtime costs in comparison to replacing solid bearings of a similar size. SRB split roller bearings allow the shaft to be supported by the lower section of the bearing & housing whilst the upper section of the housing & the bearing outer race can be removed. This makes bearing inspection fast and simple, without the need to disconnect drives or lift the shaft. This intrinsic feature is especially valuable regarding large rotating machines, where sheer weight and size can be a barrier to fast and effective servicing.

Companies are increasingly embracing the fact that to achieve performance gains they must first achieve improved production efficiencies. To achieve these longer term efficiencies it may be more cost effective to specify components that initially cost a little more, but will reduce maintenance and repair costs during their long service life, therefore offering the customer a lower ‘whole life cost’ and reducing the total cost of ownership (TCO). It is the classic case where the component with the lowest initial price, often does not offer the customer the lowest lifetime cost.

Understanding the application and its maintenance requirements are crucial in making the best decision with regard to the design of the bearings used. In the first instance determining the type of load, axial or radial, is important to ensure that the correct design of bearing is selected, along with the sealing requirements and issues such as potential misalignment. Usually, for critical bearings in large rotating equipment, regular scheduled inspections are required, which can result in considerable periods of down time.

The installation design of the application and the ancillary equipment such as coupling design will also determine the amount of shaft movement that is allowable during a bearing replacement operation. Usually there is insufficient space to allow the shaft to be lifted and to remove the bearing housing without the requirement to dismantle large pieces of plant.

In some cases there may be insufficient space available to mount the lower half of the support pedestal during bearing replacement, unless the shaft itself can be lifted, so the maintenance time can be very protracted unless a more innovative design of split roller bearing support pedestal is available.

With SRB split roller bearings, the spherical location between the bearing housing and the support pedestal ensures that under conditions of shaft misalignment, and irrespective of the type of seal used, the seal always remains concentric to the shaft. As a result, SRB split roller bearings perform exceptionally well in harsh operating conditions (in some cases completely submerged) even with severe shaft misalignment, whereas solid mounted spherical roller bearings can suffer from non-concentric ineffective seals that can rapidly lead to expensive premature bearing failure.

The benefits that can be derived from installing SRB split roller bearings are clear, and often the key decision is to determine the correct design and seal arrangement for the application in question.

It is understandable that during the specification stages of a new project, an OEM may choose to make short term savings by specifying the most inexpensive bearing for the application. However it is important that the end-user considers whole life costs, specifically the cost of downtime for inspection, maintenance and replacement.

Revolvo has designed the SRB SNQ (SN Quick) support pedestal which has a angled split design which solves the costly access issue, and therefore extends the split roller bearing advantages of long service life and reliability to new applications.

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