Two Chinese central government-owned enterprise subsidiaries have filed patent litigations against each other in the field of shield machines in recent years, according to the latest report. China Railway Hi-Tech Industry Co., Ltd.(CRHIC) has filed two patent infringement lawsuits against China Railway Construction Heavy Industry Co., Ltd.(CRCHI) at the Beijing Intellectual Property Court, claiming over 21 million Yuan. CRCHI has also lodged no less than 3 suits against CRHIC at the Xi’an Intermediate People’s Court and the Urumqi Intermediate People’s Court for infringing its utility model patents. According to the latest research report of Sinolink Securities, CRHIC and CRCHI are currently the duopoly of China's shield machine industry, selling 229 and 222 shield machines respectively in 2021.