One of the most important components of the TBM installed to date is the main drive, this 380-ton assembly was lowered into place by a Manitowoc 650 crane on December 7. (Select the link in the picture to view a time-lapse video of the installation.)
The blue cylinders are the drive’s 690-volt electric motors which will power the machine’s 46-foot-diameter cutterhead. The drive can rotate the cutterhead at a maximum speed of 2.3 rpm, but will typically operate between 1 and 1.5 rpm while tunneling.
After installation of the main drive, crews placed the remainder of the TBM’s wedge-shaped circular shield sections, forming the structure at the front of the machine. Next steps include tightening over 2,000 bolts to the specified torque, as well as welding the joints between the ten shield sections. Once completed, the cutterhead will be lowered into place and installed.