Liebherr L 556 - Manual (Page 15)

Quarrying // 15
The right machine configuration
A correctly configured undercarriage will
improve the performance capability of the
machine, especially in critical ground
conditions. At the same time, undercarriage
wear can be drastically influenced.
Fundamentally, crawler undercarriages
differ in the undercarriage length, the track
shoe width and the related track width. As
a general rule: a shorter undercarriage will
provide greater manoeuvr ability and higher
ground pressure on hard ground. For
optimum traction on normal hard ground
and the best possible levelling performance,
a long undercarriage with narrow track
shoes should be chosen. An extra-wide
undercarriage is used on less stable (i.e.,
soft) ground. Travel speed
Excessively high speed – especially when
reversing – can lead to increased wear on
all components.
Cornering or working on a slope
Tight corners or frequent unnecessary
changes of direction when changing tracks
can cause increased wear, especially at the
side walls of the guide wheels, carrier rollers,
track rollers and on the chain.
Ground material
The type of ground material will have the
greatest influence on undercarriage wear.
Abrasive sand, for example, can cause
wear on a chain within a very short space
of time. In less abrasive materials (top soil,
loam, coal), the undercarriage will last
much longer.
What influences undercarriage wear?
Working with the machine
Chain tension
Correctly setting the chain tension is a
basic requirement for optimal service life
of the undercarriage. Practical tests have
shown that the right chain tension can lead
to a service life of the bushing up to 75 %
longer than with the chain overtensioned.
The service life of the sprockets is also
lengthened accordingly. If the chains are
too loose, this could cause the teeth to
wear on one side of the sprocket.
On Liebherr crawler tractors under operating
conditions, the chain should hang down by
between 1.2 and 2.4 inches, depending on
the model, between the guide wheels and
Tip 6: In especially high-wear operations in
soft material, rotating bushing chains can
substantially increase the service life of the
undercarriage. Because of their form, these are
only of limited suitability for tough operations in
which impact stress occurs.
Tip 7: The chain tension can easily be
measured with a board or rod positioned
between the guide wheel and the first carrier roller.
Make sure that the machine is measured under
realistic operating conditions as the chain may be
additionally tensioned by the buildup of material
on the undercarriage.
Tip 8: In general, it is advisable to use a
centrally fitted chain guidance system with
crawler undercarriages. Such a chain guidance
system will absorb some of the lateral forces created
when steering or driving across a slope. Alternatively,
the undercarriage can be fitted with a continuous
chain guard that protects the entire undercarriage
against foreign bodies.
Check your speed
If the chains start to slip this will increase
wear on the track shoes. Drivers should
always adapt their travel speed and blade
load according to the operating conditions
in order to prevent the chains from slipping.
In addition, it should be checked whether
the webs on the track shoes are sufficiently
high to allow optimal traction. This will
greatly improve the pushing performance.
Service
the carrier roller or between the carrier roller
and the gear ring. The correct chain tension
can be easily set with a grease gun. Please
refer to the operating handbook of the
construction machine for details. To prevent
injuries, it is important for the safety
instructions to be observed.
Tip 9: Freely variable or hydrostatic drive
systems allow travel speed to by optimally
adapting to all operating conditions and types of
ground. Because the optimal travel speed can also
be set at full engine speed, there is always sufficient
tractive power available. The efficiency of such
drives is constantly high over the entire speed range
and no manual gear shifts are needed. That makes
fuel consumption especially low compared to
conventional construction machines.
Tip 10: For operations on hard or stony
ground, a suitably narrow track shoe width
should be selected as the chain could be damaged
by the lateral forces created when wide track shoes
are used.