B.F.R. 37 ÷ 200 KW  -  RADIAL CUTTING BOOM

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 bucket-boom.
Obviously, excavated debris are removed using a separate machine.
Compact in-line cutting units can be used on materials having a compressive strenght up to 500 daN/cm².
With the same power, cutting parameters and material, radial cutting heads offer higher productivity than in-line cutting heads.
The excavator weight must be appropriate to cutter power : for radial groups rated up to 45 kw an excavator of at least 16 m/tons is sufficient ; for 200 kw the minimum weight is 45 tons.

 
   

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.

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