Patent ID: 7186182

Claim:
A drive line for a down hole mud motor, comprising: a central shaft having opposed ends and an exterior surface; a ball seat at each of the opposed ends of the shaft; end housings, each having an interior surface and a centrally disposed ball seat; an integrally formed engagement spline on the exterior surface of the shaft and the interior surface of each of the end housings; balls positioned between the ball seat at each of the opposed ends of the shaft and the ball seat in the end housings, thereby facilitating omni-directional pivotal movement between the shaft and the end housings; a plurality of elongate keys extending radially from the exterior surface of the shaft at each of the opposed ends, the keys being axially movable relative to the exterior surface of the shaft; a plurality of circumferentially spaced axial keyways in the interior surface of the end housings which are adapted to receive the keys, the keyways being formed by overlapping the engagement spline of the end housings and the engagement spline of the shaft; and each of the keys having opposed sides, opposed ends, a back face and a front face that is radiused in a first direction between the opposed ends and in a second direction between the opposed sides, thereby accommodating the omni-directional pivotal movement of the shaft relative to the housing, the front face of each of the keys protruding past the engagement spline.