Rockhead (SBU-RHSS or SBU-RHDS) Technical Description The Robbins Rockhead is ideal on longer utility installations (over 1,000 ft) where line and grade are critical. The Rockhead is available in Double Shield (SBU-RHDS) or Single Shield (SBU-RHSS) models. The Double Shield Rockhead is self-propelled using a gripper system. The Single Shield Rockhead must be used in conjunction with a pipe-jacking system or primary liner erected in the tailshield. Muck is removed using a small invert auger, vacuum system or muck cars. Guided Tunnelling The Rockhead can be steered throughout the drive from an operator’s console inside the rear shield. Articulation cylinders and stabilizer pads allow for continuous control of line and grade. The machine’s heading can be continuously monitored using a laser targeting system. A Cost Effective Solution The Rockhead offers more efficient excavation than typical carbide bit or roller cone cutting heads. Most carbide cutting tools tend to break off in rock above 11,000 psi UCS. The Rockhead uses disc cutters to chip away hard rock from 4,000 to over 25,000 psi UCS. ROCKHEAD APPLICATIONS • Line- and grade-sensitive crossings • Replacement for carbide bit and roller cone cutterheads • Long bore lengths over 1,000 ft • Pipe jacking AVAILABLE FOR PURCHASE OR LEASE

Side View gripper assembly (double shield only) articulating front shield drive assembly bearing housing assembly belt conveyor operator station thrust cylinder muck car assembly Front View SPECIFICATIONS MACHINE DIAMETERS MACHINE LENGTHS ROCK STRENGTHS GROUND CONDITIONS Medium to hard rock, or mixed ground CUTTERHEAD FEATURES MUCK REMOVAL OPTIONS THRUST SYSTEM FEATURES • +/- 2 degrees articulation for steering • Man access to face for cutter inspection and replacement • Center shaft style cutterhead support • Both hard rock and mixed ground versions available CUTTER OPTIONS • Belt conveyor •...