The most commonly used machinery for hard rock tunnelling. It can also be used for cutting soft rocks with additional equipment as ring beams erector rockbolter and shotcrete manipulator. It is recommend to cut rock with UCS ranging from 50 to 300 MPa, 10% - 100% PQD value and joint spacing greater than 0.6m.

Wirth gripper TBM consists of the basic units with outer and inner Kelly the back-up system

The inner Kelly is a strong structure with square-section. Inner Kelly, which is mounted in the axially movable outer Kelly, carries cutterhead, main bearing and main drive.

The outer Kelly clamps on the tunnel wall in two planes. The clamping position serves as steering for the inner Kelly and acts as support for thrust cylinders which thrust the cutter head against the tunnel face during drive.

Scraper, loading slot and shovel wall on/inside the cutterhead collects and brings muck into the machine's belt conveyor, which is installed in the inner Kelly or on the top of the machine, depending on the machine's diameter and specific tunnelling conditions.



  • Precise machine guidance thanks to clamping in two planes
  • Low energy losses thanks to minimized friction
  • Safe transmission of forces and high flexibility in fault zones thanks to distribution of clamping forces to several grippers
  • Easy access to roof and invert for both staff and equipment thanks to central arrangement of inner Kelly
  • Uniform weight distribution thanks to rear-end location of the thrust cylinders and drive


Xikang railway Qinling tunnel

It is China's longest mountain railway tunnel with uptrain tunnel length of 18,460 meters and downtrain tunnel length 18,456 meters. These two tunnels are almost parallel with 30-meter spacing. Qinling tunnel made its breakthrough in August 1999 with 32 days in advance of schedule. According to the statistics, the average monthly advance rate is up to 268 meters and maximum advance rate is 528 meters.

Jilin Yinsong Water Transfer Project

A gripper TBM with boring diameter 8.03m, successfully developed by CREG based on its National R&D Program (863 Program and 973 Program), is adopted to drive a total of 20km of water diversion tunnel for the Jilin Yinsong Water Transfer Project. The tunnel passed through limestones, granite, diorite, muddy siltstones and tuff from 40 to 130 MPa UCS. The maximum overburden of the tunnel is up to 260m and the shallow overburden section is expected to encounter strong weathered rock, fault and broken sections.

Gripper TBM