Schaeffler supplies its largest-ever spherical plain bearing

Designing the special bearing was not the only major challenge faced by Schaeffler’s experts – producing it was also highly demanding. The inner and outer rings were created with a single-piece design.

• The special bearing for a cutter suction dredger application has an outside diameter of almost two meters

• The asymmetrical design saves installation space and weight

• Production of the single-piece inner and outer rings was made possible by Schaeffler’s expertise

Schaeffler has produced the largest spherical plain bearing in the company’s history to date. This special bearing weighs in at around 4.7 tons and has an outside diameter of 1,900 millimeters, a bore diameter of 1,500 millimeters, and a height of 600 millimeters. The bearing will be used on a cutter suction dredger that was designed and built by Royal IHC, a Dutch company that specializes in equipment, vessels, and services for the offshore, dredging, and wet mining markets.

Special operating conditions
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, e.g. 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 motions that take place between the hull and the pipeline. On the basis of these requirements, a special bearing was designed specifically for the application.

Expertise for the customer – everything from a single source
Thanks to Schaeffler’s high-level expertise in application engineering, design, and production combined with a close collaboration with Royal IHC, was it 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 it 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.

High operational reliability with a low maintenance outlay
The bearing has to eliminate the edge stresses that occur and support large forces according to its dimensions. Because the forces only act unilaterally on the spherical plain bearing, it was designed asymmetrically, making important savings possible 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 swiveling motions 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.