New Sealing Solution Protects Bearings

A new sealing solution prevents costly shaft damage in the event of bearing failure.

OEB’s many years in the bearing industry have shown that bearing failure often leads to shaft damage. In many cases signs of bearing failure are difficult to detect, which often makes it almost impossible to predict the exact moment of bearing failure.

This is particularly true on long conveyors where monitoring is difficult. There are many reasons why bearings fail so OEB has developed a sealing solution to mitigate premature bearing failure.

Once the cage fails, the rolling elements are no longer guided and disperse in all directions at the bottom of the housing. As soon as the rolling elements stop rolling, sliding friction occurs, flattening the rollers and the shaft starts dropping down. The shaft eventually makes contact with the cast iron housing in the seal area, causing damage to both the housing and the shaft.

In many cases it is difficult or impossible to replace the shaft. A new bearing is then fitted to the damaged shaft. But there is now a large gap between the shaft and the housing, resulting in ineffective sealing and allowing dirt to enter this gap, causing premature failure of the new bearing.

Preventing shaft damage

Herman Zandberg, the Mechanical Supervisor at Tronox, was lamenting shaft damage as depicted on his conveyors. He remarked that it was strange that there was no seal on the market that could prevent such damage.

Almost all of OEB’s customers had the same problem and so too did its sales engineers who often assist with fitting the first Split Roller Bearings.

OEB started testing various sacrificial seal materials. They removed the cage and rollers from the test bearing and ran the shaft on the seals, thereby simulating a bearing failure. These tests developed a sacrificial seal carrier that provides effective sealing, yet in the event of failure, the seal carrier would wear away without damage to the shaft.

At slow speeds (100 RPM), like a conveyor, the sacrificial seal lasted many hours before wearing away. At high speeds (1 000 RPM), typical of a fan, the wear was quick. However, in all cases there was no shaft damage. This provides the end user with invaluable extra time to spot and address a failed bearing before shaft damage occurs, potentially reducing unforeseen expenses dramatically.

Improving bearing life

In addition to this innovation, engineers subsequently fitted the Split V-Ring seal in an attempt to improve bearing life. The Split V-Ring Seal is held in place on the shaft by a cable tie. The lip runs against the side of the housing, preventing dirt from entering this space. It is important to remember that while this is very effective against premature bearing failure, with time the lip wears off and needs to be replaced regularly. A minor cost compared to bearing failure.

“In the past our opposition copied all our designs, namely our “SN” and “SD”, followed by the “SNQ” and “SDQ”. This time we have globally patented our design. Our patent covers Split Roller Bearings, as well as Plummer blocks, since we believe that there will be a demand to retro-fit these seals into existing housings, as well as new housings,” Herman concludes.

OEB

Nica Smith

Tel: (011) 493-4463

Email: nica@oebearings.co.za