Team up with the most capable mid-sized
machine on your next hard rock bore

Get the most efficient and valuable tool for excavating longer hard rock bores. If you have a project that requires accurate line and grade or if you need to bore a longer drive, then the Robbins Rockhead could be the most successful solution for your project. Since each project is different, each solution will vary. To find out if this system is the best fit for your project, read carefully about the machine itself and all of the options Robbins has available.

What is the Robbins Rockhead?

The Robbins Rockhead is a powerful mid-sized tunneling machine modeled after larger TBMs that generates torque from a drive unit mounted at the cutterhead thrust bearing assembly. Each Rockhead is custom designed to fit your project’s specifications, and is available in both Single Shield (SBU-RHSS) and Double Shield (SBU-RHDS) models.

Rockheads employ a different excavation method from the Robbins SBU-A, which is dependent on the auger for torque and a standard boring machine for thrust. Double Shield Rockheads are self-propelled using a gripper system, while Single Shield Rockheads must be used with a pipe-jacking system or primary liner erected in the tail shield. Torque is achieved through an in-shield drive motor.

The Robbins Company has the right machine for your job. Let us help you select the right machine from our proven designs.

Project Specifications and the Machine Solution

Bore Diameter:

The diameter range for the Robbins Rockhead is available between 54 inch (1.35 m) and 78 inch (2.00 m).

Bore Length:

For bores that are over 1,000 ft (300 m) in length. The maximum bore length is dependent on ground conditions and other
specifications on your project.


The Robbins Rockhead can be used in conjunction with:

  • Steel casing
  • Reinforced concrete pipe
  • Ring beam and board
  • Four flange liner plate

Spoil Removal Options

There are several methods to consider, and most are dependent on the length of the bore and what equipment you already own.

  • Machine belt conveyor to invert auger: For short to mid-sized bores
  • Machine belt conveyor to small muck car with removable muck box

Standard Machine Features and Benefits

Cutterhead Capable of Cutting Hard Rock

This robust head cuts the hard rock with single disc cutters. The cutters are located on the cutterhead in a geometric pattern that allows the disc to create a kerf (crush zone). The thrust at these kerfs creates fractures and cracks in the rock face, which ultimately forms chips of rock.

Articulating Front Shield

This will allow you to steer the machine and ensure accuracy of line and grade. The forward shield can be articulated in any direction necessary to allow accurate line and grade when used in conjunction with a laser guidance system.

Man-Access to the Front of the Machine

In the case of longer bores or difficult ground conditions, it may be necessary to go to the front of the cutterhead. In the case of longer bores or those in hard rock, the cutters will need to be changed. Whether or not they need to be changed is highly dependent on the ground conditions (the harder the rock and the less brittle it is, the more cutter changes will be necessary). In the case of an obstruction, the man access will allow the operator to clear the obstruction and continue boring

Operator Station and Lighting

The operator station is located underground within the Rockhead shield in order to make fast corrections. This allows for precise line and grade.

Laser Targets

With the use of a laser and a target, the machine will bore accurate line and grade through shield articulation.

High Capacity Bearing Housing Assembly

Our robust thrust bearing is suitable for longer drives at higher thrust.

Patented Single Disc Cutters

Our specialty cutters are the best in the industry. This high quality and value product results in minimal or no cutter changes for drives below 500 ft. If you have a project that requires cutter changes or if you simply want to learn more about Robbins cutters, click here

Customized Solution

Some projects have special requirements for which the normal Robbins Rockhead package may need modification. Any sized machine can be modified in these ways:

Cutterhead style and design

If mixed ground conditions call for special cutter tooling, we offer scrapers, ripper teeth, bullet bits, and backhoe teeth.

Cutterhead drive systems

Available with either hydraulic or electric motors.

Thrust Method

For Single Shield models, pipe jacking and on some projects Auger Boring Machines (ABMs) can be used for thrust. A push ring is available when liner plates or ribs and board are installed. For Double Shield models, a gripper system similar to those found in larger diameter TBMs provides forward thrust.

Power Umbilical

For starting pits that have limited right of way. It is possible to split the control shield and the forward shield so that the control station is above ground and the gripper shield is in a shorter starting pit.