PD and VT Fuzes Training Module Overview

Training Module 4
Click Cannons to Advance Frame
155mm Ammunition
Training Program:
Point Detonating and
Variable Time Fuzes

Overview
PD and VT Fuzes
The history and functionality of the
fuze types contained in this
module are very different.
The one common fact is that
both can only be used on
Burster-type projectiles.
The Point Detonation family of
fuzes have a lineage that can be
traced back to crude percussion
fuzes — widely used during the
American Civil War.
Modern PD fuzes function either
upon contact or with a slight
delay. They are used in all terrain
scenarios against hard targets,
like simple bunkers or entrench-
ments and are also used to
neutralize enemy troops in the
open or mechanized vehicles.
PD fuzes are the most common
fuze used in Field Artillery
operations and are prized for their
consistent performance and at
$30 per item are the most
economical fuze in inventory.
Point Detonation and
Variable Time Fuzes
Overview

Overview
PD and VT Fuzes
The Proximity Fuze (VT) family
was developed by the United
States Army (evolving from British
AAA fuze designs) and were first
deployed in WWII at the Battle of
the Bulge in 1944. This fuze was
the most deadly conventional
weapon developed during WWII.
In his memoirs, General Dwight D.
Eisenhower lists the Proximity (or
VT) fuze as one of the main
reasons the Allies were able to
defeat Nazism.
This fuze type will initiate a
Burster Projectile at a very
specific (…airburst ) distance from
its target maximizing the effects of
shell fragmentation upon its
target. This is achieved by a
RADAR system contained within
each fuze that is used to measure
distance to the target and initiate
the bursting charge explosive
train. More details will be
presented later in this module.
The VT fuze also has an
automatic PD function which
serves as backup in case of
primary malfunction.
Variable Time Fuzes
Overview

Overview
PD and VT Fuzes
In this module you will receive
instruction detailing the function
and use of the PD fuze:
• Different types of
• How it functions
• Primary and alternative uses
• Setting the fuze
And use of the VT fuze:
• Different types of
• How it functions
• Handling and installation
requirements
• Setting the fuze
You will receive an interactive
training session followed at its
conclusion by a digital multiple
choice test.
NOTE: DO NOT SET TIME ON
A FUZE WITHOUT THE FUZE
BEING ASSEMBLED TO A
PROJECTILE.
Variable Time Fuzes
Overview

Types
PD Fuzes
The only point detonation fuzes
covered in this module are the
most common…, the MASKED
and the MASKED.
Point Detonation
The main distinguishable feature
between the two fuzes are the
holes located in the upper portion
of the nose on the MASKED (the
significance of this will be
revealed in the upcoming
segment).
MASKED MASKED
Both fuzes offer the setting
options of “SQ” (superquick) and
“Delay.” The delay setting will
interrupt initiation by MASKED
seconds this allows for surface
penetration or for a planned
ricochet which would then result in
an airburst of the projectile.
Setting of these fuzes require an
M-18 fuze wrench.
Use flat-tip of M-18 fuze wrench for
setting of delay functioning

MASKED
A cutaway view of the MASKED
would reveal the following
components:
Interior Components Head
Firing Pin
Support
Firing Pin
Detonator
Flashtube
Interrupter
Delay Plunger
Initiation
Components
Booster
Note: A delay setting will bypass
the energy delivered through the
flashtube into a secondary
system, which provides the
MASKED second delay before
initiation.
The design of this fuze presents
a significant issue … the firing
pin being positioned directly
against the head of the fuze
provides hyper-sensitivity to
contact.
PD Fuzes
WARNING: DO NOT FIRE THIS
FUZE IN HEAVY RAIN OR
DURING HAIL STORMS.
Point Detonation

MASKED
PD Fuzes
A cutaway view of the MASKED
would reveal the following
components:
Interior Components Crossbar
Holding
Assembly
Crossbars
Crossbar
Holes
Firing Pin and
Detonator
Assembly
Interrupter
Flashtube
Delay Plunger
Initiation
Components
Booster
The design of this fuze is an
improvement over the MASK due
to the firing pin being recessed
3/4-inch and positioned within a
1/2-inch diameter sleeve. This
reduces the impact of rain upon
the firing pin/detonator assembly
and lessens the sensitivity to
contact.
The next segment details the
functional workings of the
crossbar assembly.
Point Detonation

Types
VT Fuzes
The basic fact about this fuze type
is that it is NOT A TIME FUZE.
Variable Time
The variable time fuzes covered in this
module are the MASK and the MASK.
A time fuze actuates at the
moment that the time setting has
expired. The time set upon a
VT fuze does not initiate the
bursting charge explosive train,
but allows the fuze to pick up the
reflection of it’s own sound
emission. An illustration of the
entire process appears later
in this segment.
Special handling requirements are
necessary when utilizing this fuze
type … and are as follows. MASKED
MASKED

Components
VT Fuzes
Many of the components built into
the VT Fuze are delicate and
must be handled accordingly,
here are the interior components.
Nose Cone (Hollow)
Antenna
Assembly
Amplifier
Assembly
Timer
Assembly
Power
Assembly
Initiation
Components
Booster
Interior Components:
NOTE: The nose cone of the VT
Fuze is painted black to reduce
static electricity.
NOTE: DO NOT HANDLE THE
NOSE CONE OF THE VT FUZE,
Handling will disable the sensory
function of the fuze and cause
primary malfunction.
NOTE: DO NOT DROP ANY VT
FUZE, a drop of only 4 feet may
cause the electrolyte vial in a VT
Fuze battery (located in the Power
Assembly) to break, thus creating
a dud when used.
Variable Time

Setting
VT Fuzes
Setting The VT Fuze:
• Then use the M27 Fuze Wrench
• Apply fuze to projectile and
tighten with M18 Fuze wrench
...which mates up
with a machined
indent in the nose of
the fuze body
The M27 fuze wrench
sports a locking tine...
Variable Time

Setting
VT Fuzes
Setting The VT Fuze:
• Then use the M27 Fuze Wrench
• Apply fuze to projectile and
tighten with M18 Fuze wrench
• Rotate the fuze clockwise to set
as needed
NOTE: This fuze may be
rotated in either direction
without effect on the
mechanisms contained within
If the required time setting is
passed, reverse rotation 1-2
seconds past the required time
setting and then make your final
adjustment in the direction of the
original rotation…clockwise.
Variable Time

Function
How it Works:
Once the projectile leaves the
muzzle of the weapon, the
radio transmitter is activated
and begins sending out
continuous waves toward the
target.
Each fuze has a clocklike
mechanism set to control the
activation of the radio
receiver. Once the time set
has expired then the receiver
becomes sensitive to
rebounding sound waves.
As the projectile approaches
an object, the sound waves
are reflected back to
the fuze and are picked
up by the receiver unit.
When the incoming waves
reach a predetermined
intensity, an electronic switch
is thrown which initiates the
bursting explosive train.
Radio
transmission
begins
Once obstacles are
cleared, the set time
expires activating the
receiver unit
Intensity
reaches
critical point
VT FuzesVariable Time

7 meters is the
predetermined
distance.
Function
VT Fuzes
NOTE: In case of primary
malfunction, the VT will
function as PD.
The MASK series VT can be
set in range between
INFORMATION MASKED seconds
The MASK series VT can be
set in range between
INFORMATION MASKED seconds
Assembly of the MASK VT Fuze
requires removal of the supple-
mentary charge from the
projectile fuze well. Remove
the supplementary charge
only by means of its lifting
loop and turn in the supple-
mentary charge as excess with
the dunnage turn-in.
For PD functioning on the MASK …
90 seconds must be set on the
time scale, the MASK comes
factory set upon PD.
NOTE: Do Not Use the VT Fuze in
combination with the MASK WP
Projectile.
Variable Time

FFE
Click On The Button
To Take The Test
References
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PD and VT Fuzes Training Module Overview

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