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Some drivers look back to do their work,
torsioning or streching their back.
In some cases drivers bend to access commands or devices.
Those movements combined with high level of vibration or
shocks show increased effects on the human body.
When adding commands or devices into the cabin make sure
that they are easily accessible by the driver |
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Make sure
that the vehicle and particularly the seat is
checked and correctly maintained on a regular basis
and according to manufarcturer recommandations.
Suspended seats lifetime is often shorter than the
one of the vehicle. |
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The best
vibration rejection is implemented using a suspended
cabin or chassis, combined - if possible - with a
suspended seat. In some cases a suspended seat might
be enough to attenuate vertical vibrations.
Different type of suspension exist (mechanical,
pneumatic, etc); they must be adapted to the type of
vehicle.
The seat must exhibit accessible adjustments
allowing the driver to easily adapt its driving
position to its size, weight and confort according
to manufacturer's recommandations.
When purchasing seats, select a type that has been
tested for the type of vehicle you want to mount
them on. If not correctly chosen, a seat may
increase the vibration level instead of reducing it! |
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Seat adjustment to
driver's weight is capital. Adjusting the seat to its weight, the
driver set to suspension to mid-range. This is the basic requirement
for the suspension to operate correctly. Drivers sometimes don't use
this adjustment correctly: they use it as a height adjustment,
impacting the suspension stroke and hence its efficiency.
Pneumatic
suspension automatically adapt seat rest position to mid-range.
Forward/backward
and tilt adjustments are also important. Those allow the
driver to set a correct position for commands access.
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Slopes, bumps, and steps
on the driving surface increase the risk.
Don't
underestimate the tyre selection. Good tyres filter
out ground roughness.
Excessive
speed increases the effect of vibration especially
when driving on bad surfaces.
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Vehicle manufacturers declared
vibration values are useful when purchasing a new vehicle.
Be aware that they may underestimate the severity of real
exposure under given circumstances (i.e. when executing
particular tasks).
More accurate exposure values resulting from large-scale
measurement campaing can be found over the internet (i.e.
http://umetech.niwl.se).
But only measurements done on a given vehicle, driven by a
driver on a given surface and performing given tasks allows
to know exactly the vibration exposure level without any
assumption. A easy-to-use device like EVEC allows to perform
those measurement very efficiently. |