Robbins Small Boring Units (SBU-A)

The Small Boring Unit (SBU-A) is a proven solution for medium to hard rock utility installatons up to 150 m in length. The SBU-A can be used with any conventional auger boring machine (ABM) from 0.6 to 1.8 m in diameter and utilizes a full-face auger for spoils removal. Before excavation, the SBU-A is welded to the lead casing. A full-face auger is added to the casing and the assembly is lowered onto the ABM track. In hard rock, the circular cutterhead is fitted with disc cutters, while in mixed ground a combination of ripped tetth, drag, bits and disc cutters are used.

This product breakthrough was possible by including the patented 6" Mini Disc cutter in the design of the small diameter cutterhead and main bearing assembly, duplicating the rock cutting principle of large TBMs.


Technical specifications:
ModelBore øCutters No.Cutter sizeTorque RequiredThrust RequiredLengthWeight
mmmmNmkNmmton
SBU-A 2466091657865 - 10575200 - 40010000.861
SBU-A 3081091657865 - 10575200 - 40010401.12
SBU-A 3697013165, 24117085 - 22.915290 - 5809401.54 - 1.61
SBU-A 42112016165, 24126170 - 34980380 - 7609301.72 - 2.25
SBU-A 48127019165, 241, 29233355 - 46610420 - 84011403.04 - 3.72
SBU-A 54142021165, 241, 29241490 - 55460470 - 94011403.38 - 4.29
SBU-A 60157014165, 241, 29251800 - 69000830 - 156012655.56 - 6.62
SBU-A 6617301529263800 - 85100890 - 167014167.71 - 8.07
SBU-A 72188016292, 35686920 - 1082001000 - 178014227.94 - 8.26
Main advantages:

  • Unmatched boring performance in hard and abrasive rock
  • Production rate can reach up to 1 meter per hour in hard sandstone
  • Long life of disc cutters compared to standard carbide bits and therefore
  • Very reasonable cost of consumeables per bored meter
  • The SBU is used with an existing or inexpensive available thrustboring machine
  • Most reasonable solution for small diameter hard rock boring on the market

Small diameter hard rock tunnel boring machines starting from 1500 mm diameter are available on
request. We also supply thrustboring, pipejacking and microtunnelling machines.


We reserve the right to change technical specifications without prior notice.