Section XIII. PUMPING SYSTEM
rewind button, located beneath the hose reel assemblies
on the instrument panel. The heat exchanger is mounted
The fire truck pumping system consists of a
in the engine compartment, and circulates water through
centrifugal-type pump, rotary vacuum priming pump,
the engine cooling system from the pumping system to
steady valve, relief valve, water tank, foam, and two
cool the engine. The primer oil tank is mounted on the
motor driven hose reels. A series of operating valves,
engine cab beneath the right-hand seat. It supplies oil to
drain valves, and a foam proportion regulator, regulate
the primer pump.
operation of the fire pump for pumping water, or a water
and foam combination.
The centrifugal-type pump
122. Primer Pump
develops pressure and capacity, by means of centrifugal
force, and must be primed before it will lift water. The
priming system consists of a rotary vacuum pump
(1) Remove the primer pump motor and
operated by a 24-volt electric motor controlled through a
solenoid relay (para. 105).
manual priming valve which actuates a microswitch
(2) Refer to figure 59, and remove the primer
controlling the electric motor.
Water pressure is
pump from the water pump manifold.
controlled manually by a throttle knob and is held
b. Cleaning, Inspection., and Repair.
automatically by the relief valve. The relief valve is
(1) Clean all parts with an approved cleaning
adjusted to any pump pressure up to 300 psi. The hose
solvent, and dry thoroughly.
reels are electric motor driven, and actuated by a reel
Figure 5.9. Primer pump and universal joint, removal and installation.