Abstract: The apparatus serves as a length of drill string and has a valve actuatable from the surface that restricts the drilling fluid channel to produce a pressure drop within the apparatus. The pressure drop is used to move a piston which moves a side loading element against a well bore wall to urge the drill string toward the opposite wall to cause a progressing drill head to change direction. The housing that carries the side load element has a clutch that rotationally disengages the housing from the drill string when the element is extended. The drill string can drill as a rotary system while the side loading element is stationary relative to earth.

Abstract: The valve, has an orifice and cooperating poppet with the poppet situated to approach the orifice to an extent determined by a controlling crosshead that reciprocates axially in response to manipulation of the mud flow moving through the valve. The amount of restriction provided by the valve is varied by selected manipulation of the drilling fluid flow controls at the surface. Pressure provided to controlled machinery is regulated by a valve by-pass channel. Changes in the standpipe pressure indicates the state of the valve action achieved down hole.