Helmet Weight Support
Development responsibility: UWA/HARC
Origin of concept
Deminers complain that the helmets they wear are too heavy and uncomfortable.
They prefer to squat rather than lie down for prodding, thereby exposing
themselves to much greater risk of serious injuries in the event of an accidental
mine detonation. The helmet weight is also uncomfortable when working with
a metal detector (standing, looking at the ground 1 - 2 metres in front).
The size of the existing inventory makes wholesale replacement too expensive.
James Trevelyan suggested a device which supports all or part of the
helmet weight in a lying position. Abdul Hadi Popal later emphasised the
need for support in the standing position when using a metal detector.
Demonstration prototypes:
Several produced - see details below
Simulated field demonstrations:
Videotape of Trials December 1996 & June 1997 (in Peshaware, Pakistan)
Simulated field testing
In progress at Risalpur, Pakistan (November 1997 onwards)
Safety tests:
Required for establishing blast effects on helmet with visor fastened
in the down position, coupled with helmet support device in use. (Note that
UNOCHA require all visors to be permanently fastened down because several
deminers have received injuries as a result of working with the visor part-way
down.) Tests will be needed for the prone, squatting and standing positions.
Safety tests are unlikely to cause permanent damage to prototypes, but visors
will probably need replacement.
Current status (December 1997):
Version 3 shows considerable promise. It is lightweight and very simple.
15 field test prototypes have been manufactured in Pakistan and have been
evaluated by UNOCHA and demining teams.
Results:
It is effective in relieving the helmet weight in the standing, squatting
and prone (lying down) positions. It does not work well on sloping or uneven
ground.
The helmet support needs some minor modifications before wide-scale use
to make it easier to adjust for different wearers and in different conditions.
The harness and cusion bag needs an additional strap around the chest to
keep it correctly positioned. The strap around the back of the neck could
be wider for more comfort.
However, a new light weight helmet imported from Australia could provide
greater comfort and adequate protection if blast testing at Jalalabad (by
UNOCHA) proves it to be satisfactory. A decision on further development
of the helmet weight support will be deferred until these tests are completed.
Back-mounted unit (version
1)
Origin of concept
The first idea was to attach a support frame to the deminer's back through
a special harness. The helmet would be supported by an arm projecting above
the head. (See early reports).
|
helmet/helmetsupport1-s.jpg
|
Demonstration prototype
One was produced at UWA in September 1996. However, it could not be secured
to the deminer's back. In use, it tended to move up towards the head because
of the large relative movement of the shoulder blades when the deminer adopts
a lying position.
Status (Oct. 1996)
Abandoned. |
Support bar (version 2)
Origin of concept
When version 1 did not work after a frustrating series of attempts, and
was clearly quite unsuited for relieving the helmet weight in the standing
position, James Trevelyan devised a simple support bar which required only
one adjustment.
-1-s.jpg)
helmet/supportbar(2)-1-s.jpg
-2-s.jpg)
helmet/supportbar(2)-2-s.jpg
|
Demonstration prototype
One was produced at UWA in December 1996. The prototype was taken to
Pakistan for evaluation in January 1997.
Simulated field demonstration:
Videotape of simulated field demonstrations December 1996. Photographs
in "Suggestions for Tools and Techniques for Deminers, February 1997".
(Circulated to demining teams in Afghanistan).
Comments:
1) Possible blast effect causing helmet with visor fastened down to be
blown back off deminers head. Bar would catch under chin, possibly causing
severe injury.
2) Cumbersome in use. Requires some practice to use effectively. Tends
to swing round in front of deminer.
3) Concept is attractive to deminers.
Status (February 1997):
Abandoned as the next version's (version 3) design overcomes all the
limitations. |
Support frame (version
3)
Development responsibility: transferred to HARC
in June 1997
Origin of concept
James Trevelyan devised an alternative support bar made from 12mm (half
inch) aluminium tube. Unlike version 2, it is symmetrical, much smaller
and lighter, and cannot swing freely out of control.
|
helmet/helmetsupport-2.1-s.jpg
helmet/helmetsupport-2.2-s.jpg
|
Demonstration prototype
One was produced at UWA in May 1997 by Chris Couldrick. Simpler prototypes
have been built by HARC in Pakistan.<,P>
Simulated field demonstration
Videotape from ABC News broadcast 22nd May 1997. Photograph in Australian
Newspaper. A prototype was taken to Peshawar,Pakistan, for evaluation in
June 1997.were it was enthusiastically received by ATC senior staff.
Safety tests
Required for establishing blast effects on helmet with visor fastened
in the down position, coupled with helmet support device in use. Tests will
be needed for the prone, squatting and standing positions. Safety tests
are unlikely to cause permanent damage to prototypes, though visors will
need replacement.
Status (Sept 1997)
15 prototypes have been made in Pakistan for simulated field tests and
evaluation by demining teams and UNOCHA.
Deminers are enthusiastic about this innovation (ATC comments, May/June
1997). |
Catch/Pivot (versions 2/3)
Development responsibility: UWA
Origin of concept
The catch pivot mechanism used on versions 2 and 3 of the helmet support
provides an elegant 2 axis offset pivot for the helmet support. The helmet
pivot pin only requires a very minor modification to the helmet: a 6mm hole
in the helmet top.
Version 2 also had a quick release device (push button on top and pull
up) which used internal balls which slot into a groove in the pivot pin
on the helmet. However in version 3 this is no longer required.
(The catch mechanism was susceptible to dirt/grit becoming
trapped between the steel button and the aluminium housing. This could
be avoided by suitable O-rings or preferably sealing rings designed for
minimum friction sealing. An alternative concept uses side buttons (on
opposite sides) releasing spring steel catch levers.)
The offset pivot for the helmet support bar or frame should be behind
the pivot pin when in use. This is important to keep the weight of the helmet
correctly supported.
|
helmet/catch.pivot-1-s.jpg |
Demonstration prototype (version 3)
Noting that version 3 of the support frame does not allow the frame to
be removed without also removing the helmet (i.e. they are used together),
a much simpler catch can be used. There is no longer a need for the quick-release
mechanism. |
Harness (version 2)
Development responsibility: UWA
Origin of concept
The harness used for version 2 of the helmet support was adapted from
a standard 40Kg back pack designed by Gondwana Gear Ltd of Perth. This has
been popular with trekkers.
When demonstrated to deminers in January 1997, they suggested it was
over designed and would be too hot in summer.
Harness (version 3)
Development responsibility: transferred to HARC
in June 1997
Origin of concept
Based on comments gathered from deminers in Pakistan on the field visit
in January 1997, version 3 was adapted from a few components of the original
harness and a chest cushion (see below).
It is much lighter and simpler to produce.
|
-1-s.jpg)
helmet/supportbar.harness(3)-1-s.jpg |
Harness version 3 (UWA prototype)
This one was produced at UWA in May 1997 and demonstrated to deminers
in June 1997. They were enthusiastic.
It incorporates the chest cushion (inside the blue bag). |
A further prototype was made in Pakistan (June 1997). The chest cushion
(see below) was made 75 mm wider and 150 mm longer (from deminers' comments).
A batch of 15 have been made and are under evaluation in Pakistan with the
helmet supports.
Chest cushion (version
2/3)
Origin of concept
Charles Trevelyan suggested a chest cushion could be provided to the
harness to provide comfortable support for the deminers chest, particularly
on stony ground. Thus the harness is effectively a pouch which can be stuffed
with foam according to the needs/comfort of each individual deminer. It
also provides a convenient potential storage place for location markers
which could be secured to the pouch exterior by Velcro when not in use.
|
helmet/chestcushion-HARC-1a-s.jpg
helmet/chestcushion-HARC-1b-s.jpg
|
Demonstration prototype
One was produced at UWA in December 1996 as part of the version 2 harness,
and it has been retained in version 3.
Deminers have suggested that it needs to be about 50 or 75 mm wider,
and about 150 mm deeper.
Pockets may be useful for marker stones and other tools.
Status (October 1997)
Initial batch of 15 have been made in Pakistan. |
Helmet Safety Strap
Development responsibility: transferred to HARC
in June 1997
Origin of concept
Deminers no longer use the helmet chin strap since the visors are fastened
down (an adjustment made following some deminers being injured as a result
of keeping their visors half or fully up). The chin strap might cause a
broken neck if a blast wave catches the visor and pushes the helmet off
the head.
Deminers can, therefore, easily lose their helmet which would be a great
inconvenience if the helmet falls off on, say, a steep mountain path. Potentially
the helmet may roll down into a minefield.
The strap consists of a length of elastic "bungee" cord secured
to the deminers belt in the middle of the back. It can also be secured to
the helmet support harness. With suitable adjustment, it can also help prevent
the helmet falling off the deminer's head forwards (perhaps onto a mine)
during prodding.
|
helmet/fan.bungee-1-s.jpg
|
Demonstration prototype
Constructed in May 1997 for simulated field demonstration and demonstration
to demining groups in June 1997.
Status (July 1997)
Available when needed. |
Helmet Ventilator Fan
Development responsibility: UWA
Origin of concept
To provide greater comfort in hot weather by drawing fresh air into the
helmet around the edges. This will promote cooling by evaporating water
in sweaty hair.
On cold winter mornings, this may help by reducing the tendency for moisture
to condense on the inside of the visor.
Demonstration prototype
Constructed in December 1996 for simulated field demonstration.
Unfortunately, the delicate fan was damaged before it could be tested.
An improved fan mounting was installed for demonstration to demining
groups in June 1997 (the helmet fan is portrayed in the diagram
for the "bungee" strap).
Battery powered unit (version 1)
The initial model was battery powered. The June 1997 demonstration used
a 12 volt sealed rechargeable lead-acid battery. It was demonstrated to
ATC in Peshawar, June 1997, on a hot afternoon and received with great enthusiasm.
Deminers were very impressed. It made a big difference.
The unit needs to be re-designed to make it robust (so that the helmet
can be dropped on the fan cover without breaking the unit), and a solar
power unit is needed.
Solar powered unit
Development responsibility: UWA
If we continue to use the 12V CPU fan, a field test model will require
a solar electric power supply consisting of a number of low voltage solar
cells connected in series feeding a DC/DC converter to boost the collector
voltage of about 3 volts to about 12 volts. A small NiCad battery will provide
continuity in intermittent sunlight. This will power the fan for about 30
minutes while operating inside a building or in deep shade.
An Italian manufacturer has presented us with a solar sun shade with
an in-built miniature solar cell and electric fan. This costs about US$7-00.
Status (December 1997)
The Italian fan was fitted to a light-weight construction helmet for
evaluation in hot weather in Perth and demonstrations in Pakistan/Afghanistan.
On a day when the temperature was about 32 Celcius and 70% humidity, the
fan provided quick relief, stopping sweating on the head during physical
exertion, and providing very effective cooling and comfort enhancement.
Deminers are enthusistic, but we have to devise a rugged and effective
design integrated with a helmet.
We would welcome collaborators to work
on related devices.
We will supply you with reports and working drawings, papers etc., provided
you agree to joint publications arising from this.
Contact
us
| Demining Home Page | James Trevelyan's Home Page
| UWA Home page |
For
more information on any of these send us E-mail at demining@mech.uwa.edu.au
All graphics by Demining Research
Team. Aug 1998.
Webmaster: Edin Tabak
|