Down reaming apparatus

摘要

A down reaming apparatus has an upper stabilizer which supports the down reaming apparatus in the bored hole. A plurality of shoe assemblies are radially attached to the hub of the upper stabilizer. The shoe assemblies are biased against a bored shaft wall by pressurized cylinders which allow limited return movement with resistance of the shoe assemblies. A weight assembly comprising a plurality of stacked plates is secured to the frame of the down reaming apparatus and has manways therethrough which allow passage of workers. A lower stabilizer provides additional support for the down reaming apparatus. The lower stabilizer also includes shoe assemblies that are biased against the bored shaft wall by a pressurized cylinder.