Freudenberg seals are being used in one of the world’s most important tunnel construction projects: a tunnel under the Yangtze in
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