Liquid treatment apparatus for filtering liquid under pressure

Liquid filtering apparatus for providing a flow of pressurized liquid and filtering the pressurized liquid, said apparatus comprising, in combination:

• a hydraulic cylinder defining a cylinder interior;
• a divider dividing said cylinder interior into first and second compartments;
• a first piston head within said cylinder interior, said first piston head being movably mounted in said first compartment and forming a liquid-tight seal with said hydraulic cylinder to subdivide said first compartment into a first set of two subcompartments, said subcompartments of said first set of two subcompartments located at opposed sides of said first piston head;
• a second piston head within said cylinder interior spaced from said first piston head, said second piston head being movably mounted in said second compartment and forming a liquid-tight seal with said hydraulic cylinder to divide said second compartment into a second set of two subcompartments, said subcompartments of said second set of two subcompartments located at opposed sides of said second piston head;
• a double-ended ram member movably mounted within said cylinder interior and extending between said first piston head and said second piston head, with a first end of said ram member connected to said first piston head within a single subcompartment of said first set of two subcompartments and a second end of said ram member connected to said second piston head within a single subcompartment of said second set of two subcompartments, said ram member extending through said divider, movable relative to said divider, and forming a fluid-tight seal with said divider;
• first liquid flow path defining means defining a first liquid flow path extending between the two subcompartments of said first set of two subcompartments;
• second liquid flow path defining means defining a second liquid flow path extending between the two subcompartments of said second set of two subcompartments;
• pressurized liquid delivery means having an outlet for pressurized liquid;
• control means for alternately introducing pressurized liquid from said pressurized liquid delivery means outlet into said first and second compartments to cause reciprocal movement of said piston heads and ram member within said cylinder interior and pressurization and flow of liquid through said liquid flow paths from the subcompartments of the sets of two subcompartments not accommodating a ram member end to their respective subcompartments accommodating a ram member end;
• liquid exit path defining means defining a liquid exit path communicating with said liquid flow paths for discharging excess pressurized liquid from the subcompartments not accommodating a ram member end and not entering the subcompartments accommodating a ram member end;
• and
• filter means operatively associated with said first and second liquid flow path defining means for receiving pressurized liquid from said first and second liquid flow paths and filtering said pressurized liquid.