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2
Safety notes
Further notes
The following notes are designed to complete the Op-
eration and Maintenance Manual to ensure that your
tractor always works safely, reliably and efficiently.
Tractors are mainly designed for towing implements that
are held by a drawbar or three-point linkage or for driving
implements using the PTO.
To obtain the greatest possible towing force, particularly
when using a tractor with dual rear wheels, you should
observe the following rules concerning axle loads and
wheel slip.
If an extra implement is attached, the extra loads must
conform to the specifications given in the Manual or by
your dealer.
1.
Front axle payload: 4WD tractors.
The front axle normally bears 40% of the tractor weight
on the road without implements; it may thus be nec-
essary to add an extra weight on the front end to
ensure that the front axle has traction.
If an implement is mounted on the front end of the
tractor, check the weight of the fully loaded imple-
ment by placing the front axle on a scale: the maxi-
mum axle load must be less than the capacity of the
front axle.
Check the maximum payload capacity of the front axle
(maximum weight allowed on it) in your Operation and
Maintenance Manual).
2.
Rear axle payload.
The maximum permissible payload for the rear axle
depends on whether or not the tractor is carrying a
weight or towing a load.
When the tractor is only carrying a load, without tow-
ing, the wheels must have sufficient capacity that is
ensured if the tyres are of the exact size and have the
specified number of plies.
In certain conditions, extra weight may be applied to
the rear axle but it is not normally necessary unless the
ground offers very little grip.
When fully loaded, the weight of the tractor must be
less than the maximum permissible ballasted weight
since the tractor cannot be loaded right up to the
maximum static payload for each of the axles, front
and rear, at the same time.
3.
Ballast and wheel slip.
Wheel slip must be measured for the tractor to oper-
ate efficiently during tillage.
On normal terrain in good operating conditions, wheel
slip should be between 4 and 10%.
On loose soil, wheel slip can exceed 12%.
If wheel slip is found to be greater than this amount,
proceed with care as operating conditions might
quickly become unstable and cause early tyre wear.
In certain conditions, it might be better to add ballast
in order to reduce wheel slip, but this increases the
workload of the transmission and thus reduces the
working life of the tractor.
Read the operation handbook or ask your Dealer who
will be able to help you ascertain the maximum
ballast weight you can use in normal working
conditions.
Using dual wheels or wider tyres, the tractor will
have greater grip but the workload on the transmis-
sion will also be greater in dry and difficult soil
conditions.
Dual wheels or wider tyres can sometimes be mounted
for use on slippery or sandy terrain but the axle weight
on hard, dry surfaces must be limited as the greater
grip provided by wider tyres can damage the trans-
mission.
The only torque limiter in transmission is wheel slip.
4.
Front axle lead when four-wheel drive is en-
gaged.
In a 4WD tractor, the ground speed of the front wheels
must be slightly greater than that of the rear wheels,
in order to ensure traction.
The front wheel advance must be preferably
between 1% and 4%, at an rate not over 5%.
Greater percentages may be used only on very soft
ground.
The tyres supplied with your tractor have been checked
for the correct advance of the front wheels, but when
you change them, make sure you use tyres of the
same make and size in order to maintain the same
speed ratio between front and rear wheels.
If tyres of different makes are used, their size and
internal pressure may modify this ground speed ratio,
or advance. This could increase the load on the front
axle and lead to unacceptable operating conditions,
excessive tyre wear and, in extreme conditions, dam-
age to the front axle or to the transmission.
Changes in the weight of the tractor, in the pressure
or size of the tyres can cause the tyres themselves to
bounce. This is not only annoying for the driver in the
cab, but it can also cause a loss of grip and excessive
wear in the transmission unit.
