Magnetically coupled and self-lubricated pump with bearing burnout protection

A pump comprising:

• a housing plate having a front face and a back face;
• a housing can fixed to the plate and defining a chamber on the back face thereof;
• a bearing sleeve in the can fixed to the plate and extending rearward from the back face thereof along an axis;
• a rotor shaft extending axially through the sleeve and having a front end and a rear end;
• bearings supporting the rotor shaft in the sleeve for rotation therein about the axis, the shaft having an outer surface spaced a predetermined inner radial distance from an inside surface of the bearing sleeve;
• an impeller on the rotor-shaft front end in a pump chamber at the front face of the housing plate;
• a rotor body fixed to the shaft rear end and extending axially forward in the can around the bearing sleeve, the rotor body having an outer surface spaced a predetermined outer radial distance from an inside surface of the can, the inner radial distance being smaller than the outer radial distance;
• an electric motor magnetically coupled to the rotor for rotating same about the axis;
• and
• control means for detecting excessive current consumption of the motor and thereby detecting bearing failure.