Drill tool of compact design

摘要

A drill tool having a telescopic drill rod system is used to drill anchor holes and other holes in underground mining, in particular under restricted conditions. The control of the drill rod system or of the operation of the drill tool is firstly performed via high-pressure water which is conducted through the drill rod system and becomes active in a cavity in the outer drill rod before it emerges in a restricted fashion in the region of the bit edge, in order to support the drilling operation. By means of a skilful design of cavity in the outer drill rod and of the region between the two drill rods, activated insertion of the outer drill rod is also possible due to the fact that the cavity formed between the two drill rods is deliberately filled with pressurised water at reduced pressure. <IMAGE>