TM 9-2330-356-14
(2) Float Valve.
secondary air reservoir to operate a normally closed pilot
valve A on the 3-inch control valve.
(a) This valve automatically closes the
4-inch control valve when fuel level inside tank rises to a
(3) When the normally closed pilot valve A is
predetermined level during bottom load operation.
closed, fuel from the inlet side of the 3-inch control passes
through a needle valve and into the 3-inch control valve
(b) With precheck valve in the closed
spring chamber. It also passes through normally open pilot
valves B and C on its way to the manifold.
position, fluid rises in the tank until it reaches the float
valve (fig. 4-151C).
(4) Fuel also flows through the 3-inch control to
(c) There it enters float valve and raises the
the 2-inch hose reel.
float which shuts off the fluid entering in port Y of the
float valve (load/unload valve must be in load position).
(5) As it enters the hose reels, fuel is bled off
through a pilot line, through the check valve portion of
(d) With flow shut off at port Y the pressure
deadman release valve, to the normally-open pilot valve
in the line to port Y is equalized. A spring in the 4-inch
B.
control valve then closes the 4-inch control valve and stops
the bottom load operation.
(6) The fuel pressure closes pilot valve B,
creating pressure in the spring chamber of the 3-inch
(3) Load/Unload Valve.
control valve. The additional pressure created on the
valve poppet of the 3-inch control valve closes the valve,
(a) Unlike the M970 and M970A1, the
stopping flow to the underwing nozzle.
M967, M967A1, M969, and M969A1 do not provide a
means to manually shut down flow to the 4-inch control
(7) To open the control valve, the trigger on the
valve during bulk delivery operations.
deadman control is squeezed, and air from the secondary
air reservoir is directed to the normally-closed pilot valve
(b) During these operations, fuel exiting the
A to open the pilot valve.
pump will follow two paths; one to either the piping
control or the filter/separator (dependent on operation)
(8) Once Valve A is open, the pressure in the
and the other to the 4-inch control valve.
spring chamber of the 3-inch control valve is relieved and
the control valve opens.
(c) When the fuel reaches the 4-inch
control valve inlet, the valve opens and allows fuel to
follow a path back to the pump. Consequently, the pump
(9) When the water level in the filter/separator
actually recirculates the fuel in the piping system.
sump is high enough to raise the float in the automatic
Therefore, when performing bulk delivery operations, the
drain valve, pilot pressure is sent through the pilot line
load/unload valve is switched to the unload position. This
from the automatic drain valve to the pilot valve C.
closes the load/unload valve and disrupts the flow in the
line to port Y on the float valve before it reaches the float
(10) The pilot valve C closes, creating pressure in
the spring chamber of the 3-inch control valve.
(d) Because the load/unload valve is
(11) The additional pressure created on the valve
connected in series in the line to port Y, when precheck
poppet of the 3-inch control valve closes the valve,
operation or loading operations are performed, the
stopping flow to the underwing nozzle.
load/unload valve must be in the load (open) position
(12) When water is drained from the
filter/separator, the float lowers and shuts off the pressure
c.
Deadman Control Circuit (M970 and M970A1)
to the pilot valve C. Pilot valve C opens and flow through
the 3-inch control valve continues.
(1) When the underwing nozzle is used in
d.
Removal of Control Tubing.
conjunction with the 2-inch hose reel, the deadman
control is used to control the fuel flow through the
underwing nozzle.
(1) General. The general arrangement of the
control tubing is shown in figures 4-153 through 4-155. The
(2) The deadman control S (fig. 4-152) is a
control tubing is nylon and is fastened in various locations
with straps.
hand-held control which uses air pressure from the
