World's largest Tunnel Boring Machine (TBM) main bearing in Changsha, central China's Hunan Province.

Diameter is 8.61 meter. It has power to drive a TBM of diameter 18 meter.

It has high precision. A flatness of less than 20 micrometers within an 8 meter pipe.

In past west tried China stop to make large TBM. West did not sell large main bearings.

https://english.cctv.com/2023/10/16/VIDEUZZaH9qYt0EkTuCvZo1H231016.shtml