High-performance self-lubricating bearings are being used to ensure reliable operation of the world’s largest tower clock – the Makkah Clock Royal Tower at the Fairmont Hotel in Mecca, Saudi Arabia. The bearings were supplied by the DEVA bearings division of Federal-Mogul Corporation.
According to the company, the exceptional demands created by the shafts carrying hour and minute hands each weighing around 7.5 tonnes, ruled out any conventional solutions, however the deva.bm was able to handle the combination of extreme loads, low rotational speed, intermittent motion and harsh operating environment.
deva.bm is a self-lubricating composite material, produced using a special sintering method. It is maintenance-free and features extremely high static and dynamic load-carrying capacity and a low friction coefficient, due to homogeneous solid lubricant inclusions such as graphite and PTFE, within the bronze matrix. Bearings featuring this material are ideally suited to sliding contact and greatly outperform conventional roller bearings in applications characterised by heavy loads, low rotational speeds and lack of lubrication.
The clock tower stands at 601m and features four clock faces, each 43m in diameter, legible from up to 10km away. The hour and minute hands move only once per minute, leading to huge static and inertia loads for the bearings to carry. Sand storms, winter storms, extreme daily temperature fluctuations and the high risk of lightning strikes combine to create a harsh and abrasive operating environment.