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
NOTE: If the safe condition of any fuze is in
doubt, explosive ordnance disposal (EOD)
personnel should be notified immediately.
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aircraft, the fuze arming wire is withdrawn from the fuze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
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
The M904 is thermally protected. Why is this
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
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
Table 1-2.Indications for Determining Conditions of M904E3/4 Nose Fuzes
White number 18 on green Vacant or dark in color.
White number 6 on green
18 and 6 Seconds
Green background with no Vacant or dark in color.
numbers visible. (If numbers
appear at other than 18 or 6
second setting or if numbers do
not match settings, fuze is
Any setting. (Time setting
*Red with black letter A. *Red with black Letter A.
cannot be changed.)
(Some green may show at top of