Abstract: Directional drilling of a borehole involves: positioning an apparatus in a borehole such that a housing of the apparatus and the borehole wall define an outer annular space; flowing drilling fluid to the outer annular space via an inner annular space defined between the housing and an inner drive shaft of the apparatus; actuating a clutch for selectively coupling the housing to the drive shaft for rotation with the drive shaft and for adjusting the tool face of the housing; and actuating a valve to control drilling fluid flow between the outer annular space to a piston chamber, relative to drilling fluid flow between the inner annular space and the piston chamber to thereby control drilling fluid pressure in the piston chamber. The drilling fluid pressure in the piston chamber and a biasing means act in opposing directions on a piston to urge the piston either towards or away from the borehole wall.

Abstract: Directional drilling of a borehole involves: positioning an apparatus in a borehole such that a housing of the apparatus and the borehole wall define an outer annular space; flowing drilling fluid to the outer annular space via an inner annular space defined between the housing and an inner drive shaft of the apparatus; actuating a clutch for selectively coupling the housing to the drive shaft for rotation with the drive shaft and for adjusting the tool face of the housing; and actuating a valve to control drilling fluid flow between the outer annular space to a piston chamber, relative to drilling fluid flow between the inner annular space and the piston chamber to thereby control drilling fluid pressure in the piston chamber. The drilling fluid pressure in the piston chamber and a biasing means act in opposing directions on a piston to urge the piston either towards or away from the borehole wall.