Section III. WATER PUMP ASSEMBLY
50. Pump Gearbox, Cleaning, Inspection, and
The water pump assembly consists of a main
pump, drive unit and relief valve. The main pump
includes the impeller, main shaft, main bearings and
Clean all parts in an approved
head, suction and discharge pipes, and the volute case.
cleaning solvent and dry thoroughly.
the main pump, which is driven by the power takeoff unit
b. Inspection. Inspect all parts for wear, defects,
on the truck transmission. Series of vanes on the
rapidly rotating impeller produce centrifugal force which
forces the water through the inside of the impeller, this
c. Repair. Replace or repair worn, defective, or
increases the pressure of the water and creates a
damaged parts as necessary.
vacuum which draws more water into the impeller. The
relief valve bypasses water within the pump to prevent
51. Pump Gearbox, Reassembly and Installation
pressure rise when the hose lines are shut off.
49. Pump Gearbox, Removal and Disassembly
a. Reassembly. Refer to figure 12 and reassemble
the pump gearbox in the reverse order.
a. Removal. Refer to figure 11 and remove the
pump gearbox from the pump assembly.
b. Installation. Refer to figure 11 and install the
pump gearbox on the pump assembly.
disassemble the pump gearbox.
Figure 11. Pump gearbox, removal and installation.