Self-cleaning straining device

Claim 1

A FLUID CLEANING DEVICE COMPRISING, A HOUSING DEFINING A CHAMBER THEREIN, FIRST AND SECOND DISCHARGE PORTS POSITIONED ADJACENT OPPOSITE ENDS OF SAID CHAMBER AND COMMUNICATING THEREWITH, A CENTRALLY LOCATED INLET PORT COMMUNICATING WITH SAID CHAMBER, FIRST AND SECOND INTERMEDIATE DISCHARGE PORTS COMMUNICATING WITH SAID CHAMBER, CONDUIT INTERCONNECTING SAID INTERMEDIATE PORTS, A STATIONARY FILTER ASSOCIATED WITH EACH OF SAID INTERMEDIATE DISCHARGE PORTS, MEANS DOWNSTREAM FROM SAID FILTERS FOR CREATING BACK PRESSURE IN SAID CONDUIT, FIRST AND SECOND SPACED AND INTERCONNECTED PISTON ELEMENTS SLIDABLY FITTED WITHIN SAID CHAMBER, AND MEANS FOR MOVING SAID PISTON ELEMENTS SUMULTANEOUSLY AND SUCCESSIVELY WITHIN SAID CHAMBER BETWEEN A FIRST POSITION AND A SECOND POSITION; WHEREBY WHEN IN SAID FIRST POSITION FLUID ENTERING FROM SAID INLET PORT ENTERS SAID CHAMBER, IS FILTERED THROUGH SAID FILTER ASSOCIATED WITH SAID FIRST INTERMEDIATE DISCHARGE PORT, AND IS DISCHARGE THROUGH SAID CONDUIT, SAID BACK PRESSURE MEANS FORCING A PORTION OF SAID FILTERED LIQUID THROUGH SAID FILTER ASSOCIATED WITH SAID SECOND INTERMEDIATE DISCHARGE PORT TO BACK WASH SAME AND FOR DISCHARGE THROUGH SAID SECOND END DISCHARGE PORT, AND WHEN IN SECOND POSITION THE FLUID ENTERING FROM SAID INLET PORT ENTERS SAID CHAMBER, IS FILTERED THROUGH SAID FILTER ASSOCIATED WITH SAID SECOND INTERMEDIATE DISCHARGE PORT AND IS DISCHARGED THROUGH SAID CONDUIT, SAID BACK PRESSURE MEANS FORCING A PORTION OF SAID FILTERED LIQUID THROUGH SAID FILTER ASSOCIATED WITH SAID FIRST INTERMEDIATE DISCHARGE PORT TO BACK WASH SAME AND FOR DISCHARGING THROUGH SAID FIRST END DISCHARGE PORT.