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ACCESS IN ACTION • APRIL/MAY 2015
The catapult effect and why all boom
EWP operators must wear a harness
By Phil Middleton – EWPA Training Director – EWPA guidance notes and Yellow Card
training, industry standards, supplier manuals and operator training instructs all
operators of boom type Mobile Elevating Work Platforms (MEWP), to wear a full body
harness or lanyard or a fall arrest system when operating a boom.
There is a real risk of serious injury or
death from being catapulted out of the
basket if the machine suddenly changes
height (eg: driving over a gutter or
dropping off an edge on a slope), or if the
boom swings, jolts or tilts away from the
machine’s centre of gravity. Operators
may not be in any position to avoid violent
movement of the basket, but correct use of
a harness or fall arrest system can prevent
the operator from being thrown out.
What triggers a catapult effect is a
combination of forces placed on the
machine; when it drops off a gutter or
uneven ground; it’s a sudden stop due
to lack of suspension which creates a
deflection in the boom section and expels
energy in an up or down motion.
Why is the catapult effect is so dangerous?
• Even a small movement at ground level
will create a whiplash effect at platform
level.
• The higher you are, the faster you will
be thrown forwards – or sideways – or
backwards.
• In an accident, the platform might tilt –
providing less protection than you think.
Professional boom platform operators
never leave anything to chance.
Probably the most dangerous of these
effects is if an EWP is driving down a
gutter or off a drop of some kind, reversing,
basket first. The catapult effect will be
in reverse which causes the operator to
be pushed to the floor. While there is an
upward bounce on the machine itself, most
of the energy is moving down.
While there’s a critical warning the
operator should heed, in
some cases, the drivers tend
to keep reversing, thinking
if they go slower they can
mitigate the potential for
this effect. But that’s not so.
Once it comes to the front
wheels dropping down,
the motion of the EWP will
ensure a true catapult effect
where the deflection of
the boom is in an upward
motion and the operators
are bounced upwards and
out of the basket area. For operators that
have not worn a fall arrest system the
consequences can be catastrophic. But for
operators wearing a fall arrest system there
can be no complacency placed on the fact
a fall arrest system will protect them from
harm; even still, in most cases injury will
result.
Once the operator is catapulted they will
travel to the end of their lanyard and then
will be jerked back down towards the
basket of the EWP and it’s the impact with
ACCESS in ACTION
the basket that injures the operator.
To minimise injury consideration should
be given to a full body harness with an
adjustable lanyard be used in lieu of the
standard 2m lanyard to provide work
restraint. The lanyard should be adjusted
to be as short as possible and must have
an energy absorbing device.
A work restraint system should normally
consist of a full body harness connected
to a lanyard with a shock absorber which
is connected to an anchor point on the
MEWP basket. From the anchor point, the
lanyard length should be short enough to
prevent a person reaching a position where
they could fall. Do not use retractable type
fall arresters unless they are by design
suitable to be use on a horizontal plain.
To manage the risk of catapult operators
must not mobile an ewp over rough,
uneven ground or over drop offs. To drive
an ewp from one level to another a suitable
ramp must be constructed or used that is
within the machines gradability and the
ewp must be in the retracted state.
Melbourne Scissor Lifts is now located
at 125-131 Woodlands Drive, Braeside.
General Equipment Rentals owns and
General Equipment Rentals buys scissor company
General Equipment has purchased Melbourne Scissor Lift Hire giving the company
and its customers access to an extended fleet of scissor lifts and knuckle booms and
additional lifting equipment such as telehandlers, duct lifters, forklifts, crane jibs, safety
cages and more.
operates a fleet of tilt tray delivery vehicles
to ensure hire equipment is delivered
on time every time. Contact: Melbourne
Scissor Lifts on 03 8787 9338 or General
Equipment Rentals on 03 9580 8888 or
visit website:
www.gerentals.com.au...the motion of the
EWP will ensure a true
catapult effect where the
deflection of the boom
is in an upward motion
and the operators are
bounced upwards and
out of the basket area.
There is a real risk of serious injury or death from being catapulted
out of the basket