Abstract: A system for excavating and rehabilitating underground pipelines. The system including an earth removal unit, a coating removal unit and a defect detection unit each of which is self-propelled to ride on and/or along underground pipelines. The earth removal unit includes an adjustable housing adapted to be mounted about an exposed portion of the underground pipeline. The earth removal unit further includes front and rear wheel assemblies adapted to engage the top surface of the underground pipeline. A plurality of endless belts are suspended from the housing so that they assume a position beneath the underground pipeline. The endless belts are independently operable and include a plurality of cutting/digging elements. The endless belts are offset in both the horizontal and vertical directions with respect to the underground pipeline. The coating removal unit includes at least one endless chain for removing the deteriorated coating on the underground pipeline.

Abstract: The present invention includes a self-propelled-carriage assembly which is mounted on a pipeline for removing deteriorated coating formed thereon. The self-propelled carriage assembly includes a frame having first and second sections. The first section is positioned above and detachably connected to the second section to facilitate placement on and removal from the pipeline. Front and rear rollers are attached to the upper section of the frame for supporting the carriage assembly for movement along the pipeline. A motor is operably associated with at least one of the front and rear rollers for driving the same. A first drive pulley or sprocket is mounted on the upper portion of the frame such that when the carriage is positioned on the pipeline the first pulley is disposed above the pipeline. A second drive pulley or sprocket is mounted on the lower portion of the frame such that when the carriage is positioned on the pipeline the second pulley is disposed below the pipeline.