Rotary pumps

Claim 1

A ROTARY POSITIVE DISPLACEMENT PUMP COMPRISING A PUMP BODY, A CYLINDRICAL PUMPING CHAMBER FORMED IN SAID BODY, AN OPENING AT ONE END OF SAID CHAMBER, AN END WALL AT THE OTHER END OF SAID CHAMBER, CIRCUMFERENTIALLY SPACED INLET AN OUTLET PORTS IN SAID BODY LEADING INTO SAID CHAMBER, AN IMPELLER SHAFT EXTENDING AXIALLY INTO SAID CHAMBER, THROUGH SAID END WALL, A FLEXIBLEVANED IMPELLER SLIDABLY MOUNTED ON SAID SHAFT IN SAID CHAMBER FOR REMOVAL THROUGH SAID OPENING, MEANS CONSTRAINING SAID IMPELLER TO ROTATE WITH SAID SHAFT, A SEAL HOUSING IN SAID CHAMBER BETWEEN SAID IMPELLER AND SAID END WALL, SAID SEAL HOUSING BEING SLIDABLE ON SAID SHAFT FOR MANUAL REMOVAL FROM SAID CHAMBER THROUGH SAID OPENING, FIRST SEALING MEANS CARRIED BY SAID SEAL HOUSING FOR MIMIMIZING THE ESCAPE OF LIQUID BEING PUMPED FROM SAID OTHER END OF SAID CHAMBER, AN OFFSET SEGMENT POSITIONED AGAINST THE WALLING OF SAID CHAMBER FOR FLEXING SAID IMPELLER VANED AS SAID VANES ROTATE BETWEEN SAID INLET AND OUTLET PORTS, SAID OFFSET SEGMENT BEING REMOVABLE FROM SAID CHAMBER THROUGH SAID OPENING, A COVER PLATE RELEASABLY ATTACHED TO THE BODY TO CLOSE SAID OPENING, PLATE AND SAID BODY.