Patent ID: 7543658

Claim:
A drilling means for directional drilling in a bore hole comprising a drill pipe, a drilling head, wherein rotational orientation of the drilling head determines a deviation angle of the bore hole, the drilling head including a slippable clutch for coupling the drilling head to the drill pipe such that torque due to rotation of said drill pipe can be controllably applied to said drilling head through at least partial engagement of said clutch, control means comprising a sensor for mounting on the drilling head operable to sense an actual orientation angle of said drilling head and compare said actual orientation angle with a required orientation angle adjustably set in said control means and to control said clutch such that when the actual orientation angle and the required orientation angle are the same, slip torque of the clutch equals motor reaction torque maintaining the orientation of the drilling head at said required orientation angle, and a hydraulic pump for driving a load piston of the clutch, wherein the pump includes an electrically controlled hydraulic control valve for controlling hydraulic loading applied to the load piston by the pump in dependence on the orientation of the drilling head in order to maintain the drilling head at the required orientation.