Rotary fluid pump

A fluid pump comprising a pump housing containing a pump impeller supported by a rotatable shaft, a driver for rotating said shaft, main support bearings for supporting said shaft, and back-up bearings for supporting said shaft upon failure of said main support bearings, said main support bearings comprising a bushing and thrust ring, said bushing being supported by a bushing retainer secured to said pump housing, and said thrust ring being supported adjacent said bushing by a thrust ring retainer fixed to said shaft for rotation therewith, said bushing retainer extending around said thrust ring retainer, said bushing retainer containing a counterbore for said back-up bearings, said back-up bearings having a radial clearance space with said thrust ring retainer which is greater than the radial clearance space between said main support bearings and said shaft.

A fluid pump comprising a pump housing containing a pump impeller supported by a rotatable shaft, a driver for rotating said shaft, hard main support bearing bushings for said shaft which are lubricated by the fluid being pumped, and back-up bearing bushings for supporting said shaft upon failure of said main support bearing bushings, said back-up bearing bushings being positioned between said main support bearing bushings and said driver, said back-up bearing bushings having a radial clearance space with first journal surfaces on said shaft that is greater than a radial clearance space between said main support bearing bushings and second journal surfaces on said shaft and yet small enough to prevent any shards that may result from failure of said main support bearing bushings from passing through the radial clearance space between said back-up bearing bushings and said first journal surfaces and damaging said driver.