1-19. FIREFIGHTING SYSTEM. Controls are provided in the cab and on the structural control panel to enable
firefighting in CFR or structural mode. The controls are interlocked to ensure single operator control in CFR mode, the
system can only be controlled from the cab. In structural mode, the system is controlled from the structural control panel.
Pump engagement and disengagement however, is always controlled from the cab.
To prevent inrush surges and engine overspeeding, water must always be available at the pump
before it is engaged. While operating, water supply to the pump must be continuous. If
discontinued, the pump must be shut down immediately to prevent damage.
In CFR, pump-and-roll mode, the pump must be disengaged immediately when the water tank is emptied. Failure to do
this can cause loss of vehicle control due to engine overspeeding.
a. Water Supply and Discharge System.
(1) In CFR mode water to the pump is always supplied from the tank, (see fig. 1-36) in structural mode, the
supply can be from the tank or alternative sources via the suction manifold. The alternative sources may be fire
hydrants, remote pumping units, or an open reservoir. If water is drawn from the tank for structural firefighting, a
continuous supply must be secured via the automatic tank fill valve.
(2) Automatic priming of the fire pump takes place if the pump is void of water when initially engaged. The
priming pump, driven by the fire pump, evacuates the fire pump suction. As soon as water pressure is available, the
priming pump automatically disengages.
(3) From the pump the water flows via the discharge manifold to the turrets and handline discharge valves (A)
Figure 1-36. Water Supply and Discharge System
Change 6 1-43