Patent ID: 7909090

Claim:
A downhole tool, comprising: a housing having an axis and a hole extending through the housing along the axis; a shaft located in and extending through the hole in the housing along the axis, the shaft being rotatable relative to the housing and having a limited range of axial motion; a radial bearing for reducing scale build up, the radial bearing being located in the hole of the housing for supporting the shaft relative to the housing, the radial bearing having a bushing mounted to the housing, a sleeve mounted to the shaft for engaging the bushing and rotation and axial motion with the shaft relative to the housing and bushing, and a clearance located between an inner diameter of the bushing and an outer diameter of the sleeve; spacer sleeves located on and abutting the axial ends of the sleeve as mechanical limits to maintain the bearing sleeve in a correct axial position on the shaft, the spacer sleeves having a smaller diameter than the sleeve and being formed from scale resistant material; wherein one of the bushing and the sleeve has a short axial length and the other of the bushing and the sleeve has a long axial length that is greater than the short axial length, such that axial ends of the short axial length never extend axially beyond axial ends of the long axial length throughout the limited range of axial motion.