You may mean a "close-coupled pump" in which case, that is a pump which is mounted directly on the same shaft as the driving motor: i.e. there is no baseplate or coupling to join the two shafts, drive and driven, and the pump hangs off the notor frame. A centrifugal pump is a type of pump where the liquid is forced to travel by an impeller which is inside a close-fitting chamber, or "volute" - it is probably the most common industrial and domestic pump type.

coupled

chemosmosis

i dont know about that, but i certainly pumped and drove you mother last night.

In case of emergency, if the cylinder stops, the motor does not. So it can be harmful for motor. Designers couple the high power motor to the cylinder of pump by means of a clutch. so the motor can continue to rotate while the cylinder stops.

Also in case of closing the outlet valve of a pump, the pressure in the cylinder can fail the cylinder or crankshaft and accessories. in this case the clutch can separate the power from motor to the pump and prevent failure of pump.