Abstract: A downhole percussion drilling apparatus includes a housing and a piston rotatably supported within an interior bore of the housing. A first engagement surface serves as a cam surface. A second engagement surface serves as a follower surface. The cam surface has a plurality of inclined planes each of which terminates in a drop off. With each rotation of the piston, the follower surface rises up each of the inclined planes and then falls down each of the drop offs of the cam surface thereby imparting a series of percussive hammering impacts to the piston.

Abstract: A bearing assembly is disclosed for use with a mud motor. The bearing assembly includes at least three radial bearings to protect the flow restrictor of the bearing assembly against harmful sideways and lateral loading. The bearing assembly also includes a compression nut to eliminate cracks on the mandrel at the split ring.