4-22. AIR SYSTEM - Continued
Rear brake air regulator setting 45 psig (379 kPa)
CFR water pressure/air regulator setting:75 psig (517 kPa).
Throttle Regulator setting: None; Pressure should increase gradually as valve handle is turned.
pressurize supply side to(set pressure +10
psig (70 kPa)) and hold this pressure for 10
minutes. Ensure delivery side pressure
does not increase more than 2 psig (14
kPa) during this time
(6) Depressurize both sides of the valve and
temporary air supply
(7) Install regulator in truck using capscrews.
Install air lines and fittings as removed In
step 1 of REMOVAL preceding. Coat all
Appendix E) prior to installation.
(8) For each brake regulator truck test, start
main engine and with truck fully loaded with
all normal auxiliary equipment, water and
foam, drive truck on test truck to 30 mph
(50 kph). Brake hard and ensure neither
front wheels nor rear wheels lock up
preferentially. If rear wheels lock first,
reduce pressure through regulator If front
wheels lock first, increase pressure through
regulator. Repeat the test until both axles
lock up simultaneously.
(9) For the CFR water pressure/air regulator,
start the CFR fire system as detailed in
(10) With water discharging through the roof
turret, adjust the air regulator until the pump
discharge pressure is 225 psig (1550 kPa).
When the air regulator is set up correctly
shut down the fire pump as detailed in para.
(11) For the throttle regulator, start the fire pump
in the structural mode as detailed in para.2-
11. Operate the throttle and check engine
speed Increases gradually from 800 rpm to
2250 rpm. While adjusting be sure pump
pressure does not exceed 250 psig (1700
(12) When throttle has been checked shut down
the fire system as detailed In para. 2-11.