Flow restrictor for a mud motor

An assembly to restrict fluid flow through a bearing section, the assembly comprising:

• an upper ring member having an upper ring member inner surface, the upper ring member arranged and designed to be disposed at least partially around a drive shaft and within an annulus between the drive shaft and a housing, the upper ring member having an inner diameter permitting radial movement between the drive shaft and the upper ring member inner surface,
• a lower ring member having a lower ring member inner surface, the lower ring member arranged and designed to be disposed at least partially around the drive shaft and within the annulus between the drive shaft and the housing, the lower ring member having an inner diameter permitting radial movement between the drive shaft and the lower ring member inner surface,
• an outer ring member disposed at least partially around the drive shaft and axially between the upper and lower ring members, and
• a floating ring member axially disposed between the upper ring member and the lower ring member, the floating ring member disposed at least partially around the drive shaft and being radially movable and constrained inwardly of the outer ring member, the floating ring member having a radial clearance between the drive shaft and a floating ring member inner surface, the radial clearance varying depending on the relative position of the floating ring member to the outer ring member.