Downhole mud motor

A mud motor or assembly attachable to a drill bit on its down hole end and to a power section on the other end comprising

• a) a tri-partite external housing including a lower housing section with an internal circumferential ridge around its trailing end down hole to a bearing stop on a bearing mandrel, an outer housing section with an internal ridge positioned proximate to its down hole end and a flex housing section connectable to a power section housing;
• the lower, outer and flex housing sections being attached to each other by threaded connections;
• b) the bearing mandrel, fitted within the lower and outer housing sections of a tri-partite housing which has, at its down hole end, an inner threaded section for connection to a drill bit, and on its outer surface a first frustoconical shoulder proximate to the up hole end of the internally threaded section, a circular groove positioned intermediate the first frustoconical shoulder and a second frustoconical shoulder positioned centrally between the ends of the bearing mandrel and a third frustoconical shoulder positioned proximate to outer threads on the up hole end of the bearing mandrel;
• c) a plurality of circular pressure seal means encircling the bearing mandrel and adjacent the first frustoconical shoulder for preventing unwanted leakage of fluids;
• d) a radial ring means encircling the bearing mandrel and shaped to conform to the first frustoconical shoulder and positioned adjacent the first pressure seal means for backing the pressure seal means;
• e) radial bearing means encircling the bearing mandrel and positioned up hole of and adjacent to the radial ring for rotationally supporting the bearing mandrel within the lower housing section;
• f) at least one on off bottom thrust bearing encircling the bearing mandrel and adjacent and up hole to the internal ridge of the inner housing;
• g) a bearing stop assembly removably attached to the bearing mandrel and positioned up hole to the internal ridge of the inner housing;
• h) at least one on bottom thrust bearing adjacent to and up hole of the bearing stop;
• i) a circular piston assembly positioned on the bearing mandrel within a counterbore machined on the outer housing section for separating lubricant in the bearing seal means, extending from the pressure seal means to the down hole end of the piston means, from the drilling mud;
• j) a piston stop positioned on the bearing mandrel adjacent the circular piston assembly including a piston to prevent damage to adjacent moving parts;
• k) a circular bearing adaptor attached to and partially extending over the up hole end of the bearing mandrel;
• l) a transmission section including a conical bearing adapter, with spaced apart holes around its exterior surface which lead to a central bore and provide a channel for drilling mud flow into the rear of the bearing mandrel and thence to the drill bit, with a forward portion extending over a threaded portion of the outer surface of the bearing mandrel;
• m) a transmission assembly, at least partially within a flex housing including
• 1) a flex shaft rotationally connected to a rotor adaptor and a bearing adaptor, each of which have internally threaded skirt portions with internal end walls;
• 2) a constant velocity universal joint connected to each end of the flex shaft, the universal joints having ball seats with grooved concave top surfaces terminating in at least one flow hole at the bottom of the concave top surface in which load bearing balls are positioned;
• 3) each of two bonnets are connected to the skirt portions of the rotor adaptor and bearing adaptor via a seal.