Booster pump

Claim 1

IN AN APPARATUS FOR INCREASING THE PRESSURE OF FLUID IN A PIPE LINE AND COMPRISING A CASING HAVING WALLS DEFINING AN INLET, AND ELECTRIC MOTOR WITHIN AND SPACED FROM THE WALLS OF THE CASING TO DEFINE A FLUID PASSAGEWAY THEREABOUT, SAID MOTOR HAVING A SHAFT COAXIAL WITH SAID INLET AND MOVABLE AXIALLY, AND IMPELLER MEANS SECURED TO THE INLET END OF SAID SHAFT, SAID IMPELLER MEANS HAVING AN INTAKE ADJACENT SAID SHAFT AND AN OUTLET AT A GREATER RADIAL DISTANCE FROM THE SHAFT, THE ARRANGEMENT BEING SUCH THAT WHEN THE MOTOR IS DEENERGIZED THE IMPELLER MEANS IS IN AN INOPERATIVE POSITION AND FROM SAID INOPERATIVE POSITION WHEN THE MOTOR IS ENERGIZED THE SHAFT MOVES AXIALLY TOWARD SAID INLET TO A SECOND POSITION AT WHICH SAID IMPELLER MEANS IS OPERATIVE TO PUMP FLUID FROM SAID INLET TOWARD SAID PASSAGEWAY, THE IMPROVEMENT COMPRISING: SAID IMPELLER MEANS INTAKE BEING SUBSTANTIALLY SMALLER IN DIAMETER ABOUT SAID SHAFT THAN IS THE INLET OF THE CASING; AN ANNULAR BUSHING (17) SECURED TO SAID SHAFT AND COAXIAL THEREWITH, SAID BUSHING BEING EXTERNAL OF SAID IMPELLER MEANS INTAKE, SAID BUSHING BEING OF A SIZE TO SUBSTANTIALLY CLOSE THE SPACE BETWEEN SAID IMPELLER MEANS INTAKE AND THE CASING AT THE INLET WHEN SAID IMPELLER MEANS IS IN THE SECOND POSITION, SAID BUSHING BEING MOVED BACK AWAY FROM THE CASING AT THE INLET A SUBSTANTIAL DISTANCE WHEN THE IMPELLER MEANS IS IN THE INOPERATIVE POSITION TO PERMIT FLUID TO FLOW FREELY THEREBETWEEN.