Recently, the 7.6-meter main bearing independently developed by CRCHI rolled off the production line at the Changsha Second Industrial Park, marking another breakthrough in key technologies for ultra-large-diameter main bearings. Previously, CRCHI had achieved independent development and batch application of small- and medium-diameter main bearings of 5 meters and below. On this basis, the R&D team continued to break through key technologies for ultra-large-diameter main bearings and successively developed main bearings with diameters of 6 meters and 7.6 meters, filling the gap in the product spectrum of domestically produced ultra-large-diameter main bearings for shield tunneling machines and achieving fully independent development from small- and medium-diameter to ultra-large-diameter main bearings, providing a domestic "heart" for shield tunneling machines of 16 meters in diameter and below.

The main bearing — a core key component of the shield tunneling machine

The 7.6-meter-diameter main bearing independently developed by CRCHI

The main bearing is a core key component of the tunnel boring machine. It bears the complex and harsh loads transmitted by the cutterhead drive system and controls the "vital point" for the highly safe and reliable operation and long-life stable operation of the tunnel boring machine. For a long time, main bearing products and their key technologies have been monopolized by foreign countries. In particular, the technology for ultra-large-diameter main bearings has not yet been fully broken through, and core difficulties urgently need to be solved.

To win the battle for key core technologies of ultra-large-diameter main bearings, with the support of the Ministry of Science and Technology of China, the Hunan Provincial Department of Science and Technology, the Hunan Provincial Department of Industry and Information Technology, the Changsha Municipal Science and Technology Bureau, and China Railway Construction Corporation, and relying on national science and technology plan projects, Hunan Province's top ten technological breakthrough projects, Hunan Province's "open competition" projects for key manufacturing products, Changsha Municipal Major Science and Technology Projects, and China Railway Construction Corporation's major science and technology projects, CRCHI has followed the "Four Orientations" to lead innovative technological breakthroughs. It has independently overcome core difficult technologies such as the independent design theory, precision manufacturing processes, and working-condition simulation tests for ultra-large-diameter main bearings, and successfully developed ultra-large-diameter main bearings such as those with diameters of 6 meters and 7.6 meters.

The 3-meter and 6-meter main bearings independently developed by CRCHI

In the process of developing domestically produced large-diameter main bearings, CRCHI overcame difficulties and continued to innovate, ultimately breaking through the key technologies of ultra-large-diameter main bearings, promoting the rapid development of the tunnel boring machine industry, and providing firm confidence and strong support for solving the "bottleneck" problem of core components of tunnel boring machines.