Abstract: An improved pivot ring assembly which has a first and second annular member, one of which is mounted within the other, the first and second annular members having a first and second spaced apart race, respectively, that face one another, and rolling elements positioned to roll on the races between the first and second annular members. The improvement comprises an aperture being provided in the first annular member for receiving an ultrasonic probe, the aperture having a hole therein which is directed toward a critical area of the assembly. This critical area includes an edge of the race of the second annular member. Furthermore, the races lie in planes perpendicular to the centerline of the annular members, and the first annular member is mounted within the second annular member.