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MDA Technologies 1/2016

MDA Technologies 1/2016

02 What a beautiful view

02 What a beautiful view over London 03 The hub is introduced with self-aligning roller bearing MACHINE ELEMENTS The Operators view Of course, I also wanted to know what significance the attraction has for the operator, owner and sponsor. For this I spoke with Stephanie Francis, press officer for the Coca-Cola London Eye: Mrs. Francis, could you please tell us something about the visitor frequency of the London Eye and your feeling of the accepting of tourists and the citizens of London? Although we cannot release exact visitor numbers, the London Eye receives more visitors annually than ancient wonders of the world like the Taj Mahal, Stonehenge and even the Great Pyramids of Giza. The London Eye has become a source of pride for the whole country as well as the capital – it’s the most distinctive addition to the world’s greatest city this century, loved by Britons and tourists alike. With Merlin Entertainments and Coca-Cola the City of London won a new sponsor for the attraction. What do you expect from the new partnership in the next years? For 128 years, Coca-Cola has been associated with moments of happiness and occasions that bring people together. Given this heritage, we think Coca-Cola is a great fit for the London Eye and we’re looking forward to what that brings during the partnership. Could you please give us a short preview for the future: How can you uphold the appeal of the wheel? Originally, the Coca-Cola London Eye was intended to be a temporary structure for five years but with millions boarding it every year, its popularity has prompted its lease to be extended. Today it is a permanent fixture on the London skyline and a beautiful symbol of modern London – we play an integral role in the community, have become an internationally recognised symbol for London, a hugely popular filming location and also a unique venue for corporate events, launches and entertainment. We’ll continue this along with offering the breathtaking views of London’s ever changing skyline. the 32 glass cabins, in which another 24 passengers can travel alongside me. Actually there are 3 more people in the cabin accompanying me – not tourists, Karen Preston, Marketing Manager at Schaeffler UK, Chris Head, Application Engineer in the Schaeffler Technology Center in Minworth, close to Birmingham in England, and my colleague as cameraman. “The London Eye is a superb feat of engineering which fulfills all aspects of safety, naturally also with the bearings we supplied. Our bearings were designed by our colleagues in Schweinfurt for a working life of 50 years. And this is just as well, for after the first five years of operation that were planned, the London Eye may now be allowed to remain in place on the south bank of the Thames”, explains Chris Head. The radial FAG self-aligning roller bearings were installed as fixed bearings and as floating bearings in the hub which sits on the axis of the giant wheel. Here, we are concerned only with the selfaligning roller bearing F-804543 as the floating and the F-804544 as the fixed bearing. The fixed bearing with an external diameter of 2.66 m weighs 6.3 tonnes and is fixed to the shaft. The loose bearing with its external diameter of 2.62 m and a weight of 5.2 tonnes can move back and forth on the shaft, in order to equalize the extensions in length. In order to achieve a long lifespan FAG’s engineers in Dieter Göbel’s team decided on using self-aligning roller bearings with drilled-out rollers and pin type cages. “These allow the largest number of rolling bodies per row as compared to standard cages and in this way guarantee a high radial load bearing capacity”, Chris Head explains the advantages to me. For simple installation both on the front sides of the internal as well as the external rings, threaded holes are present into which eyebolts can be screwed for installation. In order to save time and money with any exchanging of bearings which may occur in future, the German specialists have had another clever idea as a solution: the floating bearing has a larger drill-hole than the fixed bearing, so that it can be taken apart through the installation space of the fixed bearing on the side facing the river. Manufactured in record time Back to Schweinfurt in Germany: “After we had accepted the challenge to deliver the bearings, proposal drawings were prepared and we already ordered the blanks from our suppliers ahead of time – in this way we did not lose any time”, Dieter Göbel reports on the planning phase at the end of 1998. For installation reasons we still had to carry out numerous changes to the bearings. “Originally the bearings were designed for example for lubricating with 16 MDA Technologies 1/2016

oil. Due to inadequate sealing solutions, it was not possible to implement this technology at that time. For this reason, the lubication system was changed from oil-based to grease-based instead. This is one problem that we were able to quickly overcome with our experience”, Dieter Göbel recalls. And then things really moved very quickly: In mid-January we completed the changes, at the end of the month the drawings were approved by the company ‘Hollandia’ and in March the blanks we had ordered were already being delivered. The final assembly of the bearings was completed at FAG’s factory in Wuppertal (Germany) with the final fitting to the hub castings being carried out externally. Produced in case-hardened steel, the bearing’s rolling elements have a gentle convex curve, the radius of which is slightly tighter than the matching concave curve of the raceways, to ensure the load is transferred through a narrow ‘contact eclipse’ well within the roller’s overall width at all times. As might be expected, the tolerances are very small indeed: a mere 2 microns, or 0.002 mm, covering all the rolling elements, and around 10 microns for the raceways. Once the production plan had been co-ordinated exactly, the two self-aligning roller bearings were produced in only seven weeks throughput time. On the 30 th April these could finally be delivered to site. “The design and load spectra for this project were not significantly different to other large-scale projects, but the icing on the cake for us was the that we had to work close to the limits for the materials and the sizes as any oversizing would have caused un necessary costs and would have ended up heavier. In addition, up to that point we had not actually built any internal wheel bearings. However, we met the requirements and were able to deliver the ideal solution to our customer. For this reason today I still look on the London Eye with respect and pride”, Dieter Göbel explains. Bearings also provide elegance The two self-aligning roller bearings were however not the only products that FAG delivered for the Millennium Wheel. I move over to the land side of the gondola and allow my view to gaze downwards. Two radial large-scale GE 440 DW ball-and-socket joints have been installed down there below us in the two giant masts which support the London Eye, giving it the required stability. Surface pressures of over 450 N/mm 2 occur here, “With their help the wheel was swung from its horizontal installation position flat out across the Thames into its vertical working position”, Chris Head recalls this exciting piece of work. “After the large individual components were delivered onto swimming platforms and were then brought across the English Channel and the Thames right into London, we then had a four month installation phase. The hub with the self-aligning roller bearings which had already been installed by FAG’s installation project manager, and the four segments of the wheel were then assembled onto steel columns which had already The Chronology from Schaeffler’s perspective 27.09.1995 first inquiry to the bearings manufacturer FAG 16.10.1995 first technical details for the design from the company OVE Arup & Partner/UK 02.05.1996 the first proposal 28.01.1997 new load calculations by FAG 19.03.1997 change in dimensions of the bearings 30.10.1997 first inquiry from Mitsubishi Kobe, Japan 10.09.1998 inquiry from Hollandia via FAG Netherlands 21.09.1998 Mitsubishi hands the contract back 15.10.1998 first technical data for the design from the company Hollandia 18.11.1998 FAG received the contract order from Hollandia, 20 weeks delivery time 11.12.1998 Completion of proposal drawings 14.12.1998 Advance order for the blanks 08.01.1999 Hollandia visits the factory in Wuppertal, Germany – external diameter changed 28.01.1999 Approval of the bearing drawings 13.03.1999 blanks arrive 30.04.1999 Delivery of the bearings (7 weeks production throughput) 02.05.1999 Installation of the bearing into the wheel hub (4 days) 21.06.1999 Insertion of the shaft into the wheel hub (3 days) 10.10.1999 Giant wheel is raised (2 days) 16.10.1999 Positioning (2 days) 01.02.2000 Official commissioning and starts working been erected, and the bracing ropes tensioned. On the 10 th October 1999 we had then finally finished: the wheel could be set upright. That was naturally also a very important and tense moment for us too, for this showed us that our ball-and-socket bearing had been chosen correctly and mastered the objectives very successfully”, Chris Head explains. The radial large-scale ball-and-socket joints thanks to their PTFE Elgoglide floating lining, can carry extreme loads and requires no maintenance. In this way also with the very high surface pressures which occur for this type of bearing they guarantee a high working life expectancy with a low-momentum connection to the fulcrum. “Without the ball-and-socket joints a different static design would 04 Dieter Göbel (left) and Gerhard Halbig at Schaeffler headquarters in Schweinfurt, Germany 05 Two Elges bearings equalize the wind loads MDA Technologies 1/2016 17

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