The Millennium Wheel has been rotating continuously, day after day, for 10 years and is now one of the most popular visitor attractions in London, as well as a landmark of the British capital. Since opening, the total number of passengers to have used the observation wheel is more than 36 million.
At the centre of the wheel are rolling bearings, originally supplied in 1999/2000. The wheel, which was constructed using around 1,500 tonnes of steel, rotates with the help of two double row, radial spherical roller bearings, which are fitted as a locating and non-locating bearing set at the hub of the wheel.
Firmly located on the shaft, the locating bearing has an outside diameter of 2.66m and weighs 6.3 tonnes. The non-locating bearing, which has an outside diameter of 2.62m and weighs 5.2 tonnes, moves back and forth on the shaft in order to compensate for thermal expansion. These two spherical roller bearing shave a rated life of more than 50 years.
Experienced engineers from FAG Industrial Services carry out regular inspections to ensure defect-free, reliable functioning of the bearings. These checks include endoscopic inspections of the raceways and rolling elements in order to ensure early detection of any problems. Lubricant samples are also taken at regular intervals to check for particulates and abrasion.
If at any point during the Wheel’s lifetime, the bearings require dismantling, a novel, cost effective, time-saving solution has been devised. As the non-locating bearing has a larger bore (2.1m) than the locating bearing (2.04m), it can be pulled over the locating bearing seat, enabling both bearings to be dismantled from one side. Dismounting would be carried out on the river side, as the observation wheel only has a support on the land side.
As well as supplying bearings for the central hub, Schaeffler also provided large Elges spherical plain bearings that hold the London Eye in an upright position. During the original installation of the wheel, these spherical plain bearings enabled the wheel to be moved from its horizontal mounting position across the Thames and into its final vertical position. Since installation, the function of the bearings has been to compensate for micro-movements caused by the wind.
Schaeffler has also supplied spherical roller bearings for other observation wheels around the world, including the Beijing Wheel in China. The Beijing Wheel is 208m high and the bearings supplied have an outside diameter of 3.2m, a bore of 2.6m and a ring width of 630mm. Each bearing weighs more than 11 tonnes.
