New SN and SD series SRB split roller bearing units

Revolvo's development of an interchangeable split roller bearing plummer block unit is highly significant because spherical roller bearings mounted in cast iron plummer blocks are among the most common bearing types in use across all industry sectors. They are used to support rotating shafts in everything from conveyors and fans to line shafts and mill motors. Yet, despite their widespread usage, replacement is usually time-consuming and difficult due to the necessity to remove adjacent equipment. In fact, replacing a typical bearing mounted in a cast iron plummer block can take anything from several hours to many days; in contrast, replacement of SRB split roller bearing units can take as little as 1-2 hours.

The problem that Revolvo has addressed in its development of the SN and SD series split roller bearing plummer block units is that there is no ISO standard governing the boundary dimensions for split bearings. Until now, this has meant that if a bearing user wanted to replace a solid bearing with a split bearing, there was a major problem in that shaft centres are higher on split roller bearing units. As a result, the user would need to raise the shaft centres if the replacement was to take place. However, this is a major undertaking, possibly requiring structural changes to machinery, which is both time-consuming and expensive. Consequently it has always been the biggest drawback in changing from solid to split bearings.

Dimensionally interchangeable

Revolvo's new SRB SN and SD series split roller bearings overcome this problem by being dimensionally interchangeable with conventional industry-standard SN and SD ranges of plummer blocks. These new SRB bearings are said to provide a revolution in downtime reduction and plant operating efficiency. They are convenient and quick – up to 85 per cent quicker than solid bearings - to fit and remove from shafts; and they dramatically reduce the time required to change trapped bearings. In addition, they have a new design of cage clip that is retained via spiral pins in one half of the cage during assembly and disassembly. This is important because lost bearing cage clips can halt production as effectively as any breakdown. However, with Revolvo's retained design, the maintenance engineer benefits from a 'free hand', which can only speed up the bearing replacement process.

In addition to their primary role of reducing downtime, Revolvo's SRB split roller bearings offer users performance advantages not found in solid bearings. First, SRB bearing units are designed to be statically self-aligning. This means that there is no need to accurately realign the bearing housing to the shaft or any other in-line equipment, which might otherwise be required during the installation. Second, SRB split roller bearings offer users much improved reliability due to their ability to accommodate thermal expansion of the shaft within the bearing envelope itself. Third, SRB split roller bearings perform reliably in high-temperature environments, up to 140degC, without problems.

Improved sealing

They are also suitable for use in aggressive environments, due to the performance of the sealing systems available. In fact, the SRB product has inherent advantages over traditional solid bearings in the area of sealing. This is because the spherical location between the cartridge housing and pedestal support ensures that, under conditions of shaft misalignment, the seals always remain concentric to the shaft. As a result, SRB split roller bearing units perform exceptionally well in harsh operating conditions, even with shaft misalignment, whereas solid-mounted bearings can suffer from non-concentric, ineffective seals that rapidly lead to expensive premature bearing failure.

A fourth and final advantage is that Revolvo's SN and SD series split bearings satisfy the demands of specific industries where there is a requirement to inspect bearings at regular intervals, as part of a planned maintenance campaign. Revolvo's design makes this procedure a simple one. It provides 'pry' slots to enable disassembly of the cartridge housing and support pedestal, thereby reducing the likelihood of components being broken, especially in applications where the bearing unit has been installed for some time and/or where the environment is contaminated.