Schaeffler has produced the largest spherical plain bearing in the company’s history. This special bearing weighs around 4.7 tonnes and has an outside diameter of 1,900mm, a bore diameter of 1,500mm, and a height of 600mm. The bearing will be used on a cutter suction dredger that was designed and built by Royal IHC, a Dutch company that specialises in equipment, vessels and services for the offshore, dredging and wet mining markets.
A cutter suction dredger is a working ship either with or without its own drive that removes solid material from the bottom of the body of water. A vacuum is used to lift stones and transport them to shore, for example using floating pipelines. Particular strain is placed here on the connection between the pipeline and the ship, which is implemented via a spherical plain bearing that is mounted on the hull and supports the rotary motion that takes place between the hull and the pipeline. On the basis of these requirements, a special bearing was designed specifically for the application.
Because of Schaeffler’s high level of expertise in application engineering, design and production, combined with a close collaboration with Royal IHC, it was possible to produce the bearing according to the customer’s requirements in a record time of just three months.
Designing the special bearing was not the only major challenge faced by Schaeffler’s experts here – producing the bearing was also highly demanding. The shock loads that occur in the application meant that the inner and outer rings had to be implemented in a single-piece design.
The bearing must eliminate the edge stresses that occur and support large forces according to its dimensions. As the forces only act unilaterally on the spherical plain bearing, it was designed asymmetrically, enabling important savings in terms of space and weight.
To ensure a long operating life and low levels of wear, Schaeffler created a special system of lubrication grooves, which are designed in such a way that the grease is evenly distributed, even during small swivelling movements of around 20 degrees, thus ensuring optimum lubrication.
Because the operating conditions found in offshore applications also require special protection against corrosion, the sliding surfaces of the bearing were coated with a proven lubricating varnish, which ensures that no metallic contact occurs between the inner and outer rings, even in the event of insufficient lubrication. Lubrication with grease also means that the bearing is protected against corrosion. This ensures a combination of high operational reliability and low maintenance outlay for the customer.
Learn more at www.schaeffler.co.uk.