GBM Guidance System
Line and Grade Accuracy for the GBM System
The GBM Guidance System provides line and grade accuracy for the GBM system to within a ¼-in. at 400-lf. The GBM Guidance System consists of a theodolite with remote focus, an illuminated LED target, camera, monitor with computer, lateral slide and elevator column assemblies, counterweight, alignment holder, bore sight laser, plumb bobs and protective cases. For line and grade control, the illuminated LED target is placed in the lead pilot tube’s steering head. The theodolite’s cross hairs are aligned to the drive’s line and grade and the camera relays this data to the monitor with computer positioned on the GBM jacking frame mount. The operator assesses the target’s position and makes adjustments as necessary to maintain alignment. The monitor contains an outdoor flat screen computer to view the illuminated LED target in the steering head via the theodolite mounted camera. The target image can be fully adjusted for clarity and the monitor case lid acts as a visor for reduced screen glare. The monitor can be configured for data logging of thrust and rotation pressures, and number of installed pilot tubes. This information is recorded every five seconds with a concurrent image of the target screen on a flash drive for analysis upon drive completion. The optional GBM Smart Target is a multi-functional programmable target, that is used on long distance, multiple shift installations, where target clarity adjustments are required, or sleep mode is necessary to preserve battery life.