Centrifugal pumps

Claim 1

IN A PUMP HAVING A BASE, A HOUSING MOUNTED ON SAID BASE AND HAVING AN AXAIL INLET, A TANGENTIAL OUTLET AND AN OPENING OPPOSITE SAID INLET, A ROTATABLE SHAFT EXTENDING THROUGH SAID OPENING IN SAID HOUSING OPPOSITE SAID INLET, AN IMPELLER MOUNTED ON THE END OF SAID SHAFT WITHIN SAID HOUSING AND ADAPTED TO PUMP LIQUID FROM SAID INLET TO SAID OUTLET AND HAVING MEANS FOR DRIVING FLUID AWAY FROM SAID SHAFT OPENING WHEN SAID SHAFT IS ROTATING, THE IMPROVEMENT WHICH COMPRISES A BLIND PLATE FORMING THE PERIPHERAL FACE OF SAID OPENING AND HAVING A SEALING SURFACE THEREON; SEALING MEANS OPERATIVE TO ENGAGE SAID SEALING SURFACE TO PREVENT LEAKAGE OF FLUID WITHIN SAID HOUSING THROUGH SAID SHAFT OPENING WHEN SAID SHAFT AND SAID IMPELLER ARE MOTIONLESS, BUT WHICH IS DISENGAGED FROM SAID SEALING SURFACE DURING ROTATION OF SAID SHAFT; MEANS FOR CAUSING SAID SEALING MEANS TO ENGAGE SAID HOUSING WHEN SAID SHAFT IS MOTIONLESS AND TO BE DISENGAGED FROM SAID HOUSING UPON ROTATION OF SAID SHAFT; AND MEANS FOR LONGUTUDINALLY ADJUSTING SAID SHAFT, SAID IMPELLER, SAID BLIND PLATE AND SAID SEALING MEANS TO ADJUST THE CLEARANCE BETWEEN SAID IMPELLER AND SAID INLET.