Federal-Mogul Co. has supplied components for the operations of the world’s largest clock tower, which is located in Mecca, Saudi Arabia.
The Southfield-based company’s high-performance self-lubricating bearings from its DEVA bearings division are used to ensure reliable operation of the Makkah Clock Royal Tower at the Fairmont Hotel in Mecca.
The bearings were designed in close cooperation with German tower clock manufacturer Perrot. The exceptional demands created by the shafts carrying hour and minute hands each weighing around 7.5 tons, ruled out any conventional solutions, such as roller or bronze plain bearings.
Only Federal-Mogul’s self-lubricating bearing was able to handle the combination of extreme loads, low rotational speed, intermittent motion and harsh operating environment.
The new clock tower stands approximately 1,969 feet and is six times taller than London’s Big Ben’s. It also features four clock faces 141 feet in diameter, legible from a distance of six miles. 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 uniquely harsh and abrasive operating environment, noted Gerard Chochoy, senior vice president, Powertrain Sealing and Bearings.
“Federal-Mogul DEVA has refined a proven solution to suit an especially demanding application,” Chochoy said. “Our application engineers have again demonstrated our technology leadership in the field of self-lubricating bearings.”
Federal-Mogul’s deva.bm bearing 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.
“The material has proven its worth a thousand times over, especially under conditions of high load, intermittent motion and dusty or abrasive environments. This is exactly what was required for the tower clock in Mecca,” explains August Stadlmayr, managing director of Federal-Mogul’s DEVA bearings business.
Four clock movements have been constructed, one for each side of the tower. The central elements are two shafts that support the hour and minute hands, driven by servomotors. The motor for the minute hand switches on 15 seconds before the top of the minute, moving the 22-metre (approx. 72 feet) minute hand forward 60 times an hour, 1,440 times a day, 525,600 times a year.
“The very low shaft speeds and extremely high loads mean classic bronze bearing solutions with grease or oil lubrication would soon reach their limits under these conditions,” Stadlmay said.
“These heavily loaded bearings are expected to operate maintenance-free over decades in spite of extremely difficult conditions,” he added. Since the bearing have worked well in demanding conditions, they have been also been used in the toughest applications such as wind turbines, hydro-electric plants, construction, the marine and offshore industry and the iron and steel making industry.
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