Compressor lubricant equalizing pump

Claim 1

IN A SYSTEM HAVING AT LEAST TWO COMPRESSORS, EACH COMPRESSOR INCLUDING A SUMP FOR THE STORAGE OF LUBRICANT, THE COMBINATION OF MEANS FOR WITHDRAWING EXCESS LUBRICANT FROM THE SUMP OF A FIRST OF SAID COMPRESSORS INCLUDING A MEMBER HAVING A CHAMBER THEREIN; A PISTON-LIKE OPERATOR MOVABLY DISPOSED IN SAID CHAMBER, SAID OPERATOR SEPARATING SAID CHAMBER INTO FIRST AND SECOND COMPARTMENTS; SAID MEMBER HAVING FIRST AND SECOND PASSAGES THEREIN OPENING INTO SAID FIRST COMPARTMENT, SAID FIRST PASSAGE BEING CONNECTED TO SAID FIRST COMPRESSOR SUMP AT A PREDETERMINED LUBRICANT LEVEL; MEANS REGULATING SAID FIRST PASSAGE TO PREVENT OUTFLOW OF LUBRICANT FROM SAID FIRST COMPARTMENT THROUGH SAID FIRST PASSAGE INTO SAID FIRST COMPRESSOR SUMP; CONTROL MEANS ADAPTED TO COMMUNICATE SAID SECOND COMPARTMENT WITH A SOURCE OF PRESSURIZED FLUID TO MOVE SAID OPERATOR TO FORCE LUBRICANT IN SAID FIRST COMPARTMENT THROUGH SAID SECOND PASSAGE; AND MEANS CONNECTING SAID SECOND PASSAGE WITH THE SUMP OF A SECOND OF SAID COMPRESSORS.