table 1-2. It shows you what you would see through the
observation windows of the M904E3/4 fuze at various
time settings and fuze conditions.
Also, check the M904E4 to make sure the thermal
sleeve is firmly bonded to the fuze collar and is not
cracked.
NOTE: If the safe condition of any fuze is in
doubt, explosive ordnance disposal (EOD)
personnel should be notified immediately.
Functional Description
The M904 fuze arms and functions by the rotation
of the arming vane and alignment of its internal
components. When the fuze is released from the
aircraft, the fuze arming wire is withdrawn from the fuze
arming vane, and the arming vane is rotated by the
airstream. Arming vane rotation is controlled by the
constant arming action of the governor in the fuze. The
arming vane continues to rotate until the preselected
arming delay period (2 to 18 seconds) elapses (ends).
Once the arming delay period elapses, the firing train is
in full alignment and ready to function.
______________________.
At impact, the forward part of the fuze body drives
the striker body and firing pin down into the M9 delay
element. After the proper delay, the M9 delay ignites
the relay, detonator, lead, and booster, which sets off the
main charge.
Q1.
Q2.
Q3.
Q4.
Q5.
Q6.
Q7.
REVIEW NUMBER 2
What kind of fuze is the M904?
What bomb series is the M904 fuze used with?
The M904 fuze has _____ arming delays, which
you can set for 2 to 18 seconds in __________
increments; there are any combination of ______
functioning delays from instantaneous to 250
milliseconds.
The M904 is thermally protected. Why is this
important?
Describe the means you use to check the
condition of the M904 fuze.
If you can't tell if a fuze is “safe,” you should
notify ___________.
T h e M 9 0 4 a r m s a n d f u n c t i o n s by
MK 339 MOD 0 AND MOD 1
MECHANICAL TIME FUZES
The Mk 339 Mod 0 mechanical time fuze (fig. 1-2,
without the option time wire), Mod 0 and Mod 1 (fig.
1-3) are used with dispenser weapons and have the
following characteristics:
Nose-mounted
Air-enabling
Detonator-safe
Table 1-2.—Indications for Determining Conditions of M904E3/4 Nose Fuzes
Condition
Time Setting
Upper Window
Lower Window
Safe
18 Seconds
White number “18” on green Vacant or dark in color.
background.
6 Seconds
White number “6” on green
background.
Partially
18 and 6 Seconds
Green background with no Vacant or dark in color.
Armed
numbers visible. (If numbers
appear at other than” 18“ or “6”
second setting or if numbers do
not match settings, fuze is
partially armed)
Armed
Any setting. (Time setting
*Red with black letter “A.” *Red with black Letter “A.”
cannot be changed.)
(Some green may show at top of
window.)
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