FLUID DRILLING HEAD WITH POWERED SWIVEL ASSEMBLY

摘要

A fluid drilling head of the type adapted to cut a bore hole in rock by the rotation of a swivel assembly (5) within a body (1) typically has high pressure fluid nozzles providing cutting and reaming jets at the leading end (7) with the reaming jets angled to provide reaction forces to rotate the swivel assembly (5). The invention provides a positive displacement fluid driven motor (3) coupled to the swivel assembly (5) to control the rotational speed of the swivel assembly by restricting fluid flow to the motor through a metering nozzle (8).