Whether you’re drilling for oil or gas, the bearings in a mud motor at the end of a drill string have a direct impact on productivity and reliability. These mud motor bearings have to endure extreme operating conditions. In addition to severe axial and shock loads, these bearings are “lubricated” with highly abrasive mud, which for a bearing is the definition of an extreme operating condition. How the new bearing works The typical mud motor bearing contains between 8 and 12 rows for design optimization. When the bearing is new, the majority of the load is accommodated by the first four or five rows (fig. 1). As each row starts to wear, the load is shifted to the next row (fig. 2) and the next (fig. 3) until all the rows are worn equally. Then, the load is shifted back to the first row and the process is repeated. This unique design enables the bearing to last significantly longer than previous bearing designs.