SBU Division

Small Boring Unit (SBU-A)
Technical Description
The Small Boring Unit (SBU-A) is a proven solution for
medium to hard rock utility installations up to 500 ft in
length. The SBU-A can be used with any conventional
auger boring machine (ABM) from 24 to 72 inches in
diameter and utilizes a full-face auger for spoils removal.
For excavation, the SBU-A is welded to the lead casing. An
ABM provides both torque and forward thrust to the cutting head. In hard rock, the circular cutterhead is fitted with
disc cutters, while in mixed ground a combination of ripper
teeth, drag, bits, and disc cutters are used.

Cutting Through Rock
Small Boring Units utilize disc cutters from 6.5” to 14” in
diameter to excavate rock. Disc cutters penetrate the
rock face and create a “crush zone” through which
fractures propagate. Material between adjacent crush
zones is then chipped from the face. Muck scrapers
scoop the muck into openings on the cutterhead (called
muck buckets), which transfer the material to a full-face
auger for removal.

Improved Boring Efficiency
Unlike typical carbide bit or roller cone cutting heads,
the SBU-A can power through rock over 25,000 psi UCS.
Most tungsten carbide cutting tools tend to break off in
rock above 11,000 psi UCS, requiring expensive replacements and machine downtime.

A Cost Effective Solution
The SBU-A has been successfully used on hundreds of
projects around the world to efficiently excavate hard
rock. By maximizing machine availability and minimizing
labor costs, a typical SBU-A/ABM setup is economically
better than carbide bit or roller cone cutting heads.
SBU-A APPLICATIONS
• Full-face auger boring
• Replacement for carbide bit and roller cone cutterheads
• Bore lengths up to 500 ft (depending on geology)