How It Works: Motorized SBU

May 2009 Vol. 64 No. 5
The Robbins Motorized SBU holed through into mid-air in a 118-foot deep shaft, requiring a lift procedure with a hydraulic crane

Editor's note: This article refers to "Down Deep in Durango," the story of the 50-year Animas La Plata project.

The Robbins SBU-M is a manned entry, hard rock boring machine for use on both long utility installations (300 feet and over depending on geology) and crossings with specific line and grade requirements. The SBU-M is utilized with a standard auger boring machine or pipe jacking unit and is mounted with disc cutters to excavate rock from 4,000 to over 25,000 psi. In mixed ground, the cutterhead can be mounted with a combination of single disc cutters, two-row tungsten carbide insert cutters, and carbide bits.

At machine launch, the SBU-M is bolted to the lead casing using a flange, while a small invert auger inside the casing provides spoil removal. Subsequent casing lengths are welded together. An in shield motor and drive train provides torque to the cutterhead, while forward thrust is provided by the ABM through the casing.

The machine can be steered throughout the drive from an operator’s console inside the rear shield. Control of line and grade is made possible through articulation cylinders and adjustable stabilizer pads, while a laser targeting system provides accurate monitoring of the machine’s position.