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Polar bearings

Split roller bearings for icebreakers

Overcoming masses of ice up to five meters thick is no simple task. Icebreakers, however, are built to do exactly that. The special-purpose vessels have sturdy bows and hulls designed not only to break ice, but also to displace it, providing a fairway for other ships to navigate more easily.

An icebreaker can function in one of three ways depending on the situation. Most commonly, the vessel simply pushes into the ice, causing it to disintegrate under the pressure applied by the bow. However, where weight alone is not enough, the ship’s pitching mechanism comes into play. This involves large quantities of water being pumped back and forth between the bow and stern. The motion this instigates allows the vessel to cut through the ice. In some circumstances, the ship will even back up to make space for a running start, gathering enough momentum to punch through the frozen obstacle.

Bearing the strain

When an icebreaker makes a sharp turn, huge forces are exerted on its hull—as well as on its structure and mechanics as a whole. Shipowners in the Canadian Coastguard, whose fleet consists of more than 20 icebreakers, found that hydrodynamic bearings were unsuitable for this task. Previously, a ship’s generator shaft comprised two bearings—one fixed and one floating to compensate for thermal expansion. The poor accessibility to the shaft meant arduous maintenance work. It was over to Cooper, SKF specialist in split roller bearings, to provide the answer.

Cooper holds the key

Laborious maintenance procedures and subsequent downtime were constant pain points for shipowners. They sought a solution that would not involve modification of the generator itself. Indeed, the new bearing had to be a direct, “drop-in” replacement.

Cooper’s solution is a split cylindrical roller bearing containing an additional housing modification. Its split-to-the-shaft design offers numerous advantages over hydrodynamic bearings. For example, it can be accessed without other components first having to be dismantled. Furthermore, the new bearings do not require oil lubrication. This also means that pumps and filters are unnecessary and oil leaks no longer occur, resulting in reduced operating temperatures and fuel consumption.

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Cooper’s split cylindrical roller bearings on board an icebreaker.

Since the Canadian Coastguard introduced Cooper’s split cylindrical roller bearings, previously recurring faults and maintenance issues are no longer a concern. The generators function more reliably than ever before and feed electricity into the on-board power supply: Contact Cooper bearings

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