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Small Boring Machines

The compact solution for long, small diameter rock bores.

Win your next bid with the pinpoint-accurate Remote Controlled Small Boring Unit (SBU-RC). The Robbins SBU-RC was developed from many requests for a cost-effective machine that could excavate small diameter tunnels in rock with strict line and grade requirements. The Robbins SBU-RC uses a smart guidance system, allowing the machine to work unmanned during small diameter, long crossings up to 500 ft (150 m). If your next small diameter project is line-and-grade-sensitive or requires excavating long distances, then the revolutionary SBU-RC is your solution.

What is an SBU-RC?

The SBU-RC is a motorized, remotely operated mixed ground and hard rock boring machine for use with standard Auger Boring Machines (ABMs) or pipe jacking systems. In a launch pit or shaft, the SBU-RC is attached to the lead steel casing. The ABM or pipe jacking system provides thrust through this steel casing. The SBU-RC is optimized for line-and-grade sensitive bores such as gravity sewers, and operates in much the same way as a Motorized Small Boring Unit. If you are not familiar with the SBU-M, read up on this proven machine on the Motorized SBU page.

The SBU-RC is a similar concept to the SBU-M with the following additional features:

  • Smaller diameter machine: currently available between 36 inches (910 mm) and 42 inches (1,100 mm)
  • Continuous steering from an operator’s station at the surface using a smart guidance system
  • Muck removal via a vacuum line connected to a vacuum truck

To excavate the material, a circular cutterhead mounted with disc cutters fractures hard rock into chips. In mixed ground, two-row carbide cutters can be used. An in-shield drive motor provides torque for cutterhead rotation, while muck is removed via a tube connected to a vacuum truck at the surface.

Same Rugged Design, Smaller Package

The SBU-RC features the same efficient in-shield drive motor for torque, rugged bearing housing, and proven cutterhead designs used on Motorized SBUs and other Small Boring Machines. The compact design allows contractors to bore trenchless crossings and tunnels on a smaller scale, without having to upsize to larger, more expensive equipment and casing.

A Smarter Way to Steer

Intelligent steering keeps line-and-grade tunneling on the straight and narrow. The system provides not only pinpoint continuous steering, but also projections of machine position so that corrections can be made before the machine ever deviates from line and grade. An operator’s station at the surface allows the SBU-RC to be steered without introducing the human element into the tunnel, making the operation safer and logistics simpler.

Vacuum Suction

Rather than using an invert auger at long distances, the SBU-RC removes spoils using a vacuum line and truck. Efficient spoils removal keeps this machine moving fast—in fact, projects have seen upwards of 50 ft (15 m) in one day using the vacuum method.

Features and Benefits


Unlike Microtunneling machines that may be used on similar projects, the SBU-RC does not require expensive and often messy slurry operation. Because of that, the SBU-RC also does not require a large slurry separation plant at the surface.


The SBU-RC is currently available for lease worldwide. This attractive option is cost effective for contractors looking to stay competitive, and a far better option than leasing or buying more costly Microtunneling machines.


Because the SBU-RC is smaller and can be used with a Pipe Jacking System, the machine is ideal for urban projects launched from small diameter shafts and other jobsites with small footprints.


While it’s a newcomer to Robbins’ range of Small Boring Machines, the SBU-RC has already proven itself to be a rising star. Projects utilizing the SBU-RC have finished weeks ahead of schedule and excavated as much as 50 ft (15 m) per day.


The SBU-RC can bore through medium to hard rock up to 20,000 psi/137 MPa UCS or mixed ground above the water table. Mixed ground may include rock with gravel and clay seams or other non-compressible materials.