Bearing lubrication system for gear pump having clearance between bearing and housing wall for preventing entry of contaminants larger than lubrication passage

In a gear pump of the type having a housing with a pumping cavity therein, an inlet in fluid connection with the cavity and an outlet in fluid connection with the cavity, at least two gears disposed in the cavity such that the teeth thereof are in meshing engagement, a shaft journal connected to one of the gears and a bearing in the cavity for mounting the shaft journal for rotation in an interior portion thereof, the bearing having an outer peripheral portion closely conforming to the adjacent cavity wall and the bearing having a face in confronting relationship to a side face of the said one of the gears, the resultant loading upon the bearing when substantial discharge pressure is developed being such as to urge the bearing into firm engagement with the inlet side of the pumping cavity wall whereby a clearance volume exposed to discharge pressure is defined between the discharge side of the pumping cavity wall and the outer periphery of the bearing, the improvement comprising:

• a lubrication passage in the bearing fluidly interconnecting the clearance volume with the interior portion of the bearing for directing lubricating fluid to the shaft journal;
• a groove on the outer periphery of the bearing in communication with the clearance volume and the lubrication passage for supplying fluid thereto;
• the entrance to the clearance volume adjacent the said one of the gears being of a predetermined radial dimension adequate to provide satisfactory lubrication but sufficiently small to prevent entry of centain contaminants and the lubrication passage being sized larger than the clearance entrance radial dimension so as not to be obstructed by contaminants traversing the entrance and entering the clearance volume.