Abstract: Grinders, motors, engines and pumps require sealing, lubrication, and other forms of protection for shafts, bearings and packing. Fluid distribution rings and purge systems are useful aids. This disclosure illustrates a distribution ring in an enclosure surrounding a shaft. A ring surface and a confronting, radially spaced shaft surface define a clearance between them. A fluid supply passage extends from outside the enclosure to this clearance. A first centering member of the ring includes a first centering surface inclined to either side of a reference plane perpendicular to the shaft axis. Connected with a wall of the enclosure is a second centering member with a second centering surface inclined to the reference plane. Contact between the first and second centering surfaces holds the ring in predetermined radial position relative to the shaft, improves fluid distribution throughout the clearance circumference and can help exclude foreign matter from bearings and seals.