DML Mechanical clamps | Tunnel construction

Our mechanical clamps are an indispensable tool in segment production. The robust design, which does not require any drive units, is ideal for outdoor use. The mechanical clamps have been specially developed for the efficient and gentle transportation of segments. Whether you want to handle individual segments or entire stacks, the clamps can be configured flexibly. Adjustable hold-down devices allow the DML clamps to be easily adapted during operation to transport different numbers of segments.

DML Mechanical clamps

DML mode of operation:
The opening and closing of the clamps is completely mechanical. When the clamps are raised, they close and when they are lowered, they open. This reduces maintenance and operating costs to a minimum.
Hold-down device:
The DML clamps can be fitted with adjustable hold-down devices. These can be adjusted either mechanically using an insertable pin, hydraulically or electrically to set the number of segments to be lifted.
Rotating unit:
Another option is to install a rotating unit to rotate the segments by 90° if, for example, the segment bearing is not aligned in the direction of further transportation.



Grip horizontally




Reference project

Comprehensive repair of the Kerenzerberg tunnel

For over three decades, the section of the A3 highway near the Kerenzerberg tunnel has been a central part of the road network. In order to ensure road safety for the coming years and enable long-term operation, the Federal Roads Office FEDRO has commissioned extensive repairs to the tunnel section between the Weesen and Murg junctions. Work began in 2019 and should be completed by 2026. The project includes a 5,250m-long safety tunnel, which will be excavated with a hard rock double-shield TBM and lined with steel fiber segments.

Scope of delivery 

  • 1x DVL-8.0T-EXT / vacuum lifting device
  • 1x DTT-8.0T-180 / Turning table
  • 1x DPR-8.0T / Gasket pressing frame
  • 1x DML-8.0T / single-stone tongs with adjustable stop
  • 2x DML-30.0T / multi-jaw tongs with adjustable stop

"Devo-Tech AG implemented all the special functions that were necessary due to the project-specific requirements as part of the segment handling project planning. This means, for example, that all different constellations of segment and base segment stacks can be transported with the DML-30.0T segment tongs."

Sebastian Bold, Project Manager Herrenknecht AG