Positive displacement pump and thrust bearing assembly

A pumping assembly including

• a positive displacement pump with a bracket and a housing defining an internal fluid chamber having front and rear inner walls;
• a rotor positioned in said fluid chamber, said rotor having a front face and a rear face, each of said faces spaced apart from a corresponding inner wall of said fluid chamber to define predetermined clearances therebetween;
• a shaft having a first end connected to said rotor to effect rotation thereof;
• and
• a thrust bearing assembly including a bushing, an adjusting collar, and a retaining device, said bushing concentrically positioned within a central bore of said bracket such that a portion of said bushing extends outside said bore in a direction away from said chamber and such that said shaft extends through and rotates within said bore and said bushing, said retaining device positioned within an annular detent within said bore, said retaining device adapted to prevent relative longitudinal movement of said bushing within said bore toward said fluid chamber, said adjusting collar being connectable to said shaft for rotation therewith such that said adjusting collar is in relative rotatable engagement with said extending portion of said bushing preventing axial movement of said shaft toward said chamber and such that said predetermined clearances between said faces of said rotor and said inner walls of said chamber are substantially uniformly maintained as said rotor rotates notwithstanding forces urging axial movement of said shaft.