Precision bearings for solar energy

The efficiency of solar power plants – including photovoltaic (PV) and solar thermal technologies – depends on how closely the collectors are able to track the course of the sun. The more precise and trouble-free these collectors operate, the more efficient and therefore more profitable the plants will be.

Rolling and plain bearings, as well as linear units from Schaeffler are making an important contribution here. These units have high rigidity and high load carrying capacities and operate reliably even under extreme operating conditions. With its extensive range of products and specialist expertise for materials, coatings and seals, Schaeffler is an important development partner and supplier for projects that involve parabolic troughs, solar towers, Dish Stirling systems and Fresnel power plants.

In addition to standard bearings, engineered solutions for specific customer requirements are also provided. Depending on the type and design of power plant, suitable rolling bearings include slewing rings, angular contact roller bearings, ball screw drives, housed units and radial insert ball bearings, as well as track rollers. Plain bushes, spherical plain bearings and linear units are also provided.[Page Break]

Schaeffler has expanded its range of plain bearing solutions for solar energy applications. As well as ELGOGLIDE plain bearings, which have proven themselves over several years now, the product range also includes metal-polymer composite plain bearings and ELGOTEX plain bearings.

ELGOGLIDE is a sliding layer that comprises a technical woven material with support fibres, Teflon fibres and a synthetic resin matrix. The advantages of these bearings are that they are maintenance-free units and offer very high load carrying capacities, particularly if very high loads are present on one side combined with swiveling movements.

The unique characteristics of metal-polymer composite plain bearings come from the composite material, which enables low wear sliding characteristics, as well as high load carrying capacity and good thermal conductivity. The excellent formability of the material also enables customer-specific components to be engineered for various rotary, linear and swivel motions.[Page Break]

The composite materials used for ELGOTEX bearings are resistant to corrosive media and offer continuously low friction, low wear sliding characteristics, ensuring maintenance-free operation. ELGOTEX comprises two intertwined, wound layers. The internal sliding layer – which is embedded in a resin matrix with fillers and solid lubricants – is made from synthetic and PFTE fibres. The external layer comprises continuous glass fibres (filament) in epoxy resin. A specific winding angle of the glass fibres stabilises the layer, which significantly increases the strength of the plain bushing.

Rolling bearings such as Schaeffler’s AXS angular contact roller bearings, are used in double-axis tracking systems for solar thermal plants, including solar towers and Dish Stirling power plants.

Typical applications include reflector adjustment systems. High load carrying capacity, rigidity and positioning accuracy play a critical role here. These characteristics are absolutely key in enabling secure, smooth, vibration-free bearing operation for solar collectors. The bearings must also support high forces and moments, for example, during sudden gusts of wind. The bearing supports are therefore critical for the reliability and cost effectiveness of the solar power plant.[Page Break]

AXS angular contact roller bearings can be integrated in new and existing designs. The geometry of the bearing rings is identical, which means no mistakes can occur during fitting. Simple, turned bearing seats are sufficient for supporting the bearing rings manufactured using forming methods. In addition, special lubricants (both grease and oil) ensure that the bearings have extremely low maintenance requirements.
   
For more information, visit www.schaeffler.co.uk