Tunnel Borgin Machine Shanghai

Seals measuring over 10 m in diameter provide perfect protection for large bearings Primary Seal for Shanghai Tunnel Boring Machines

Freudenberg seals are being used in one of the world’s most important tunnel construction projects: a tunnel under the Yangtze in Shanghai. Construction is already underway and is expected to be completed in time for the World Fair (Expo) in 2010. The Herrenknecht tunnel boring machine (TBM) is fitted with large Merkel Freudenberg seals that are capable of reliably withstanding the huge loads that occur in the machine.


Shield excavation tunnel boring machines are used in complex tunnel projects around the world. The main bearing is the heart of these massive machines. These multiple-row roller bearings, which measure up to 6 m in diameter and weigh up to 20 t, hold the rotating cutter (Fig. 1) and support it against the enormous advance forces and massive torque that are typical of such applications. The main bearing is protected against the penetration of excavated material, stone, sand, and water by special shaft seals (Fig. 2). At the same time, these seals prevent transmission oil leakage. These large seals, which were developed by Merkel Freudenberg, are manufactured as endless molded rings without joints, can measure up to 10 m in diameter, and are produced within the narrowest of tolerances.


This kind of large seal protects the Herrenknecht tunnel boring machines that are currently being used for one of the biggest tunnel projects in the world. The plan is to open the 7.47-km long, three-lane road tunnel under the Yangtze to traffic in time for the World Fair (Expo) in Shanghai in 2010. The two tunnel boring machines that have been in use in Shanghai since the end of 2006 are the largest of their kind and have a diameter of 15.43 meters. The first tunnel boring machine is expected to reach its destination shaft on the Yangtze island of Changxing by summer of 2008. Freudenberg shaft seals are being used to protect the main bearings in these two tunnel boring machines, each of which generates a boring torque of 39,945 kNm and has an engine output of 2,500 kW.


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