Abstract: A submergible motor pump assembly is disclosed which is arranged to be easy to access to any part of the assembly with dismantling minimum elements, i.e. without requiring disassembly of the whole and without requiring discharging lubricating oil for a mechanical seal. Also, plural balance holes are provided in the main plate of the impeller and a liner ring is disposed between the main plate and the top wall of the impeller chamber to establish the flow passage from the tip of the impeller blades through the gap between the main plate and the top wall of the chamber to the balance holes with flow restricted zones by the liner ring.

Abstract: A coupling system for detachably coupling an outlet port of a submergible pump to an inlet port of a discharge conduit is constructed by a single guide rail having at least two, and preferably, two guide portions extending along the length thereof, the rail being fixed at its lower end to the conduit; an arm attached to the pump so that it is guided by the rail; and first and second engaging means provided in the discharge conduit adjacent the inlet port and in the arm respectively so that the pump is held stationary when the pump is lowered and both the engaging means engage with each other. The whole system is made compact by arranging the orientation of the guide rail particularly when it is made of an angle bar. Also, further consideration is given to effect a line contact between the first and second engaging means to reduce the severe manufacturing tolerance necessary to achieve a satisfactory coupling between the inlet and outlet ports.