Abstract: A downhole drilling motor located near the end of a rotary drill string is powered by the drilling fluid for driving a rotary drill bit for the drilling of an oil or gas well or the like. Substantially all of the drilling fluid that exits the power producing section is channeled toward the nozzles of the drill bit with a small portion being diverted through the bearings of the motor. A series of elastomer flow restrictor elements, each responding to increased fluid pressure by reducing the flow area therethrough, controls the fluid flow through the bearings to within a narrow range of flow rates.

Abstract: A series of axially stacked rolling bearing assemblies for transmitting axial thrust load between relative rotating cylinders, such as in a fluid powered downhole motor, is provided with the bearing races of each assembly formed from a bearing material significantly softer than the balls thereof so as to readily wear to a condition wherein the thrust load is generally equally distributed throughout each assembly within the stack.

Abstract: An improved quick release coupling assembly for a drive shaft of a downhole motor is disclosed. The quick release coupling has an internally tapered collar to cause the mating taper on the outside surfaces of the clutch dogs to be held firmly by the collar and in intimate engaging relationship between the mating tapered surfaces. The angle of the mating tapered surfaces is greater than a self-locking angle so that the quick release feature permits easy disassembly of the joint, and thus the tool, on the rig floor or as well as in the shop.