A detachable base for an under - reamer

摘要

A detachable base 12 for a soil working tool includes an upper surface having an attachment member comprising a surface formation 16. The surface formation 16 may be in the form of a tapered pin having an annular recess (20, fig 4). The pin may be used to engage with a clamping tool to allow the base 12 to be recovered from a bore hole.