Vacuum filter

Claim 1

A VACUUM FILTER HAVING, IN COMBINATION, A TANK ADAPTED TO CONTAIN A BODY OF LIQUID TO BE FILTERED, A MEMBER DISPOSED IN SAID TANK AND DEFINING A VACUUM CHAMBER HAVING A PERFORATED WALL FACING DOWNWARDLY, A FLEXIBLE FILTER WEB EXTENDING INTO SAID LIQUID AND ALONG SAID WALL TO COVER THE PERFORATIONS THEREIN, MEANS FOR INDEXING SAID WEB ENDWISE TO REMOVE THE USED PORTION THEREOF FROM SAID WALL AND RECOVER THE WALL WITH A FRESH LENGTH OF WEB, A POWER DRIVEN PUMP OPERABLE TO WITHDRAW FILTERED LIQUID FROM SAID CHAMBER AND BUILD UP A VACUUM THEREIN TO INDUCE THE STRAINING OF SAID LIQUID INWARDLY THROUGH SAID WEB AND INTO SAID CHAMBER, MEANS OPERABLE IN RESPONSE TO THE ATTAINMENT OF A PREDETERMINED VACUUM IN SAID CHAMBER TO INTERRUPT THE PUMPING OF LIQUID OUT OF SAID CHAMBER AND TERMINATE THE NORMAL FILTERING CYCLE AND THEN FORCE FILTERED LIQUID REVERSELY INTO SAID CHAMBER AND OUTWARDLY THROUGH SAID WEB TO RELEASE THE FILTERED-OUT SOLIDS FROM THE OUTER SURFACE OF THE WEB, MEANS FOR RESTORING THE NORMAL FILTERING OPERATIONS AFTER RELEASE OF SAID SOLIDS, AND MEANS FOR DETECTING SUBSTANTIAL CLOGGING OF THE ACTIVE PORTION OF SAID WEB AS A RESULT OF REPEATED FILTERING CYCLES AND OPERABLE TO ACTIVATE SAID INDEXING MEANS TO ADVANCE THE WEB AND RENEW THE COVERING OF SAID WALL.