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A look at subsoiler or
ripper efficiency
W
hy is ripping necessary? When tractor and implements
are used, soil compaction may take place because of
the texture of the soil and plough-pan effect by heavy
weight of large scale machinery. Soil compaction pre-
vents the root development of plants and planted crops.
Soil compaction can be solved mechanically or biologically. With
mechanical action, ripping is the most common practical method
used to loosen the soil deeply through a rip action. This gives plant
roots a chance to develop well, which produces healthy plants and
good crops.
Drawbar power required
A rip operation, however, is an action that requires a lot of traction
and energy. It therefore is very expensive, so it is important to do the
operation as effectively as possible.
Traction efficiency
Traction efficiency can be defined as the optimal utilisation of
the tractor's traction on a specific implement. However, there are a
number of factors that can affect effective traction.
Rolling resistance
Rolling resistance (
Figure 1
on page 56) is the resistance the trac-
tor has to overcome to move forward before any traction takes
place. The factors that affect rolling resistance are soil hardness,
the ground pressure that takes place under the wheels and the load.
Wheel load
Wheel weight load also plays an important role in effective traction,
but must be used in accordance with the tractor manufacturer's re-
quirements. If the wheel weight load is too heavy, it may also result
in traction disadvantages.
Graph 1
shows traction against 15% wheel slip with changed
wheel load. The graph indicates that the pulling force is reduced
when too much wheel-weight load is applied in soft soil.
Tyre pressure
Tyre pressure (
Figure 2
on page 56) also plays an important role in
improving traction. Again, it is important to follow the tractor manual
for the correct tyre pressure.
FOCUS
Implements and equipment
Special
JOHAN VAN BILJON
and
DR TINGMIN YU,
ARC-Agricultural Engineering