MechChem Africa September-October 2024

⎪ Products and industry news ⎪

Mirror of ESO’s ELT relies on SKF adjustable chocks Adjustable chocks from SKF will play an important role in the world’s largest visible/ near-infrared telescope, the ELT, which is cur rently under construction in Chile. An unsung product from SKF’s catalogue, the adjustable chock has played a key role in the construction of this huge telescope. First, Cimolai inserted extra washers, al lowing the adjustment range to be extended to 15 mm. This had to be performed with a positioning accuracy of tenths of millimetre, across the 39 m span of the mirror. The chock also had to fit into a limited design space, which was restricted to 25 mm in height. In addition, the chocks were installed upside-down, to help Cimolai meet the stiff ness requirements of the system. The high stiffness helps to reduce the weight of the mirror, which improves the telescope’s stabil ity and performance. Overall, the main mirror will use more

than 9 500 SKF Vibracon SM 16 ELP-ASTR low-profile chocks – 12 for each mirror seg ment. Chocks are individually surface treated to give them consistent quality and extend their performance in such a demanding environment. The ELT will cost an estimated €1.4-billion to build. It will, among other things, search for exoplanets and study early galaxies. Hard to think that with its vast size and cosmic ambitions, its success will rely partly on adjustable chocks just three inches in diameter. www.skf.com/africa/en

On completion in 2028, the European Southern Observatory’s ELT, now being built in Chile, will be the world’s largest visible/ near-infrared telescope. Its 39 m-wide main mirror comprises 798 separate hexagonal pieces, attached to a base structure using steel flanges and SKF Vibracon adjustable chocks. “Each flange sits on four adjustable chocks,” says Marco Colussi, a structural engineer at Italian engineering firm Cimolai, which is responsible for assembling the mirror. “The ability to readjust each mirror segment is key to the success of the telescope.” Each low-profile Vibracon unit typically allows up to 12 mm of adjustment. However, the application needed up to 15 mm of adjust ment – meaning several design tweaks were required.

The European Southern Observatory’s Extremely Large Telescope (ELT) is currently under construction in Chile.

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