By using its expertise and experience as early as possible in the design stages of building and civil engineering projects, Schaeffler can help architects, structural engineers and main contractors to select the most suitable, cost effective bearing solution.

For large structures such as commercial buildings, bridges, dams, flood gates, sports stadiums and airports, the design of the supporting bearings is critical. 

The surrounding structure can greatly influence the behaviour of the bearing and so it is important that the selection of the bearing is correct.

In the UK, Schaeffler has been involved in a number of prestigious building projects, including the London Eye, Wembley Stadium, the Lloyds  of London Building, Wimbledon Centre Court’s retractable roof and Tottenham Hotspur’s new stadium. In all these cases, early involvement from Schaeffler was fundamental in ensuring that the correct bearing solution was selected.

Why is early involvement so important?

Schaeffler UK technology centre manager Sally Sillis comments: “When sourcing bearings, various bearing design criteria need to be considered, including operational safety, load ratings, the life rating of the bearing and the lifecycle cost of the bearing, which includes maintenance and servicing costs. 

“As a bearings supplier, we can use our expertise and experience to help select the most appropriate, cost effective bearing solution.

“When we are involved early in the design process, we can provide trusted advice, guidance and engineering support from our experienced application engineers. This can save significant time and costs for the contractor in terms of redesign or modification work later on, but it should also result in a more cost effective overall design of a building or structure,” adds Sillis.

Many designers and main contractors will want a “fit-and-forget” bearing solution – one that is maintenance-free and guaranteed to last for the lifetime of the structure. Special coatings, materials or sealing arrangements can be provided to upgrade the bearing solution to one that will be fit for purpose for the expected lifetime of the project.

While this may mean higher initial costs, designers often follow this type of advice from the bearing supplier, particularly if the technical upgrade is justified and assures a longer bearing life.

The building or structure may also require the bearing to fulfil “special” duties. It may, for example, need to support several hundred tonnes in weight or withstand a harsh operating environment such as freezing temperatures, extreme heat, high humidity or high winds. In certain applications, the bearings may also need to be earthquake-proof.

Sillis points out: “If the architect or main contractor specifies a bearing themselves, they tend to consider only the maximum loads and movements on the bearing, which unfortunately does not provide a full picture of the application and invariably will lead to incorrect bearing selection, over-engineering or under-engineering.” 

Sillis says that an experienced bearing supplier would also consider the minimum loads and movements on the bearing, as well as the type of movement and the available operating envelope. This is because if, for example, a bearing is heavily loaded but well within its load carrying capacity, that bearing may suffer from “stick-slip” – a spontaneous juddering motion that occurs when two surfaces within a bearing slide over each other, often causing loud grinding noises, which in most civil engineering projects would be unacceptable. This condition can be avoided by selecting the appropriate type and size of bearing and/or by applying special low friction coatings to bearing components and surfaces.

Bearing types and examples

The bearings themselves – which might be spherical plain bearings, cylindrical bushings, rod ends, or combination bearings – should be maintenance-free if possible. A ferris wheel or swing bridge, for example, will have little time to set aside for maintenance work to be carried out.

Schaeffler offers a comprehensive range of maintenance-free plain bearings. Innovative plain bearing materials are used, such as Elgoglide, Elgotex, and the metal-polymer composite E40. These PTFE-based plain bearing materials enable ultra-low coefficients of friction for spherical plain bearings and rod ends, while ensuring low wear and very long lifecycles. Maintenance-free plain bearings considerably reduce lubricant and maintenance costs as they do not require oil or grease, while also being environmentally friendly.

Spherical plain bearings

With more than 75 years of plain bearing expertise, Schaeffler is a market leader in the design and manufacture of spherical plain bearings. Durable and capable of supporting heavy loads, its bearings ensure reliable operation, even under harsh environmental conditions. The product range is also geared towards maintenance-free operation.

Spherical plain bearings with Elgoglide 

Elgoglide is a high performance, maintenance-free sliding material based on Teflon fabric. Suitable for dynamic loads at contact pressures ranging from 1MPa to 300MPa, bearings with this layer are particularly suitable for applications that require minimal friction.

Radial spherical plain bearings comprise inner and outer rings with maintenance-free sliding layers made from Elgoglide, PTFE composite or PTFE-bronze film. This means they are suitable for alternating dynamic loads.

Angular contact spherical plain bearings comprise inner and outer rings with Elgoglide. In addition to radial loads, they can also support high axial loads.

Axial spherical plain bearings comprise shaft locating and housing locating washers with Elgoglide.

Spherical plain bearings with PTFE sliding surfaces

Schaeffler offers various PTFE-based sliding materials for specific applications. These include a PTFE composite material for compact radial spherical plain bearings for small envelopes with bore diameters as small as 6mm.