Glossary.
An independently driven cutting wheel in the centre of the main - cutting wheel. Independent rotational speed and direction of rotation of the active center cutter. Prevents the blockage of the cutting wheel through increased speed of the center tools.
Mixing arm with drive unit installed in the bottom section of the shield in front of the suction pipe. Used to agitate the bentonite suspension containing excavated material. The agitator avoids sedimentation and clogging of cohesive ground (e.g. clay) in the bottom section of the shield in front of the grip and the suction pipe.
Cavity between pipeline and the surrounding earth which occurs because of the slight intersect of the cutter head to the pipeline.
Automatic tunnelling machine with soil displacement. With this technology, the soil is not excavated but displaced into the surrounding earth.
Automatic tunnelling machine with slurry material removal, also called slurry shield. The excavated material is transferred into a closed slurry circuit in the excavation chamber. On the surface, the excavated material is then separated from the slurry water (separation).
Enhanced AVN technology with additional safety for difficult geologies and larger diameters. Control of the support pressure via an adjustable compressed air cushion. It is often also called mixshield or hydro shield.
