CHAPTER 3. REPAIR OF CENTRIFUGAL PUMP

REPAIR OF CENTRIFUGAL PUMP

head pressure necessary to cause fluid flow through

3-1. Description

the pump. The volute is secured to the seal plate.

The impeller of the centrifugal pump is

c. The volute is encased by the pump housing.

threaded directly on the extended end of the engine

The pump housing provides facilities for attaching

crankshaft. A seal plate mounted between the

the suction a n d discharge fittings. During

impeller and the engine adapts the pump to the

operation, the pump housing remains filled with the

engine, providing the required alinement between

fluid being pumped. Gaskets are installed between

the two components. A seal is installed in the seal

the volute and the housing, and between the

plate around the rotating crankshaft to prevent the

housing and the seal plate to prevent leakage.

fluid being pumped from leaking, and to prevent

air from being drawn into the pump at this location.

3-2. Removal and Disassembly

Air leakage at this point can greatly reduce pump

Remove the suction and discharge fittings

efficiency and, at higher suction lifts, prevent the

from the centrifugal pump (TM 5-4320-259-12).

pump from pumping entirely.

b. Disconnect the spark plug cable from the

b. The pump impeller is encased in a close-

engine spark plug to prevent engine starting.

fitting volute which is shaped to provide efficient

c. Remove the three nuts (1, fig. 3-1) and lock

pumping operation. As the impeller rotates, it

washers (2) that secure the pump body (3) to the

throws the fluid outward by centrifugal force. The

seal plate (14); remove the pump body by pulling it

design of the volute converts the centrifugal force to

straight out from the volute (8) and seal plate.

3-1