The heavy snow promises a good harvest. Xi’an saw the first snow in the winter on Dec 5th, when the two-way cut-through of the intercity subway between the Airport Station and Airport West Station in Xi’an. Two TBMs in the construction were all equipped with the main driver gear box, supporting small gear and gear box of screw conveyor designed and manufactured by ZPMC, of which one TBM set a new state record of the similar subway TBMs for 49.5m/d.
The shielding section between the Airport Station and the Airport West Station is 2,850m long totally, a longest one in the northwest region. It passes under the present airport taxiway, apron, oil supply pipelines and the terminal T1, making higher requirements on the construction stability and equipment reliability.
The main driver gear box of 90kw in the shielding construction is a planetary gear box of high power, density and overload developed for complex geological conditions, which is mainly intended for shielding of 6.3m in the diameter and wide use in tunnel construction of the subway with the great importance of the localization. Four new techniques are used for the first time in designing such gear box to make sure the shielding reliability in the intercity subway of Xi’an, including the built-in cooling water system to improve the heat dissipation, gear bearing complex technology to improve the service life of the bearing of planetary gear, gear of high pressure corner to improve the strength of the gear and the special load balancing mechanism for planetary gear system.