When the dimensions of the tunnel being dug do not make the use of a special machine with gathering system essential, the job can be done using an ordinary excavator fitted with a cutting system instead of the ordinary buket Obviously, excavated debris is removed using a separate machine. Compact in-line cutting units can be used on materials having compressive strenght up to 500 daN/cm².
These cutting unit have greater penetration capacity on hard terrains and provide better tunnel shaping, especially for horse-shoe tunnels.
The power of the hydraulic cutting unit is exclusively determined by the diesel engine of excavator on whose power the suitable cutting group is selected.

Rotation System with Hydraulic Jacks

The excavators used for these applications are prepared with slew powered by hydraulic jacks instead of the slewing-ring and pinion system.
This modification is of fundamental importance since it eliminates the backlash between pinion and slewing-ring, which causes impacts and vibration on the boom during excavation.
Moreover, the forces involved in cutting are too high for the pinion and slewing-ring system.

OPTIONALS

-  Water spraiyng system for the dust laying.
-  Exhaust gas depurating system.

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