Plant&Equipment

Special report
vividly shows what can happen to an operator if he
or she is untrained or the machine is not properly
maintained. This video would certainly hit home and
you could see the trainees’ faces grimace at the
staged accidents. (The HSE also has some
excellent free training information PDF downloads
on their website.)
So just what makes All Terrain Vehicles dangerous to
operate? The RNLI used Honda TRX 450S Fourtrax
Foreman quads; these bikes weigh 274kg and their
432.6cc engines make them capable of speeds over
60mph. They have a five speed auto transmission
and two or four wheel drive - all in all they are a
powerful heavy machine.
To operate these bikes safely you need to be able to
move your body weight backwards, forwards and side
to side - hence the big saddle. There is no differential
unit in the rear axle; it is just a crown wheel and
pinion, with the crown wheel being fixed directly onto
a solid bar axle. There is a differential unit in the front
drive unit with half shaft and constant velocity joints
at the wheels and gearbox end, which enables you
to steer. As a consequence of the set up with the
rear axle (both wheels turning at the same speed,
fixed) when you come to corner with the bike the rear
wheels are trying to push you straight ahead, which
can cause the bike to roll over. To counteract this
effect you need to move your body weight out to one
side, the opposite side to the corner you are turning.
This allows the nearside wheel to lift slightly and skit
the surface with the offside wheel pushing you round
the radius of the corner; in effect the opposite to a
motor cycle. If you have ever ridden an ATV on hard
surfaces you will know just how hard they are to steer
even when shifting body weight.
Ascending, descending or transversing gradients is
especially dangerous and again the big seat comes
into effect. One of the biggest causes of injury or death
is front or rear wheel overturns. So when ascending a
gradient you need to move your body weight forward
almost at an angle to the gradient. When descending
you need to move your weight back
towards the rear of the bike, again
at an angle relative to the slope.
When transversing a gradient
(which should be avoided if
possible) you must move your body
weight into the hillside, again at an
angle relevant to the slope.
distributed evenly between front and rear carriers.
Certainly – no passengers allowed.
With regards to trailers, the maximum tow hitch tongue
weight (downward load) is just 14kg. The tow hitch ball
is attached directly to the rear axle so if this weight is
exceeded the effect is to lift the front end of the bike;
the rear axle becomes the fulcrum point, which in turn
lifts the front wheels seriously affecting the steering.
If the load on the trailer is too far back then the tail
weight comes into play, with a lifting effect on the rear
wheels causing loss of traction. Most ATV’s can tow
about double their kerb weight but the trailer must
be loaded evenly allowing the axle of the trailer to
become the fulcrum; too much load and the tail begins
to wag the dog
Finally let us consider PPE. First and foremost a
helmet must be worn; they are a lot harder than your
skull! Snag proof clothing and safety boots are also
essential. Having said that I will leave you with one
last thought - can you imagine the training nightmare I
had with beach lifeguards? These girls and boys do a
fantastic job and are the unsung heroes of the RNLI.
They save many lives each year but with bleached
blond long hair and sunglasses there can be a
certain Bay Watch image to keep up! I had the task of
reaching a compromise with lifeguards, managers and
the HSE as to what they would and should wear. Steel
toecap boots were out of the question, as was snag
proof clothing, but I did win the helmet argument - all
our lifeguards wear a specially designed water craft
Gecko Helmet.
If you are going to ride an All Terrain Vehicle get
trained and you have a real work friend. Ignore
training and your ATV could become your worst foe!
Remember this: if you think the cost of training is high,
think just how much the cost of ignorance is!
Pictures kindly donated courtesy of the RNLI.
Technical data by: Graham Eaves,
Machinery Training Instructor RNLI, retired.
The bikes can carry loads and
are fitted with carriers front and
rear. There are warning notices
instructing the operator of the
maximum load to be carried
and ideally the weight should be
February 2008
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