3.
Try to reduce pivot/counter rotation turns
on hard ground. Excavators are useful
on restricted work areas because they are
able to make pivot turns, but the operator
should try to make wider turns to prevent
grouser corner wear.
The importance of maintenance
Alex Ackron is the managing director of HPE
Africa.
4.
DO:
1.
2.
Dig or excavate with the boom over the
sprocket. The overhead dig/dump cycle
causes stress and wear at the point of
sprocket/bushing contact over the sprocket.
These forces should be over the idler, where
minimal chain rail wear occurs.
Work up and down a slope rather than along
a gradient or slope. Working along a gradient
tilts the machine to one side, which increases
the load/stress on the lower track and this
accelerates overall wear on this track.
Balance slew direction under load. Because
the dig-slew-dump cycle puts pivot stress
on the undercarriage on the dump side of
the machine, the operator should balance
the slew direction by turning the excavator
around in the middle of the shift.
In conjunction with correct operation of the
excavator, it is critical to introduce a planned
maintenance programme. HPE Africa experts
have identified four maintenance tips that will
reduce undercarriage wear.
1. Keep the undercarriage clean (daily): remove
packed debris and dry material from the
undercarriage at the end of every day, using
a shovel, steel bar, or water. Dry material on
the sprocket teeth increases track tension and
also prevents the rollers from turning freely,
which accelerates wear of components.
2. Check track tension (daily): this takes no
more than 10 minutes. A track tension that is
too tight puts extra load on the engine, which
wastes fuel and is also one of the leading
causes of premature undercarriage wear. A
track that is too loose may come off and can
also cause additional shock loads and side-to-
side wear of components.
3. Inspect the undercarriage (weekly): inspect
the undercarriage for problems and if
necessary, take action. Look out for a loose
track shoe, a broken link pin, or chipped
sprocket teeth.
4. Measure undercarriage wear (every 1 000
hours): the OEM supplier or a specialist
undercarriage company should be
commissioned to check the undercarriage
after every 1 000 hours of operation.
Excessive wear on one component can
cause accelerated wear on other components
in the system. HPE Africa recommends that
track shoes, chains, rollers, and sprockets
are replaced together, rather than matching
new and used components, which results in
excessive wear of the new component.
Checking track tension
A track that is running at 20cm of slack while
requiring 30cm will experience a 300% increase
in wear stress, especially on the bushes and
sprocket. To check your track tension:
• Raise the chassis on one side using the
boom and arm.
• Remove any mud on the tracks and
frame by either rotating the track,
shovelling, or washing.
• Measure the distance — as close to the
centre of the undercarriage as possible
— between the bottom of the track
frame and the start of the track shoe.
• Compare the actual distance measured
with the recommended distance for your
excavator and decide whether to tighten
or loosen the track chain.
• Turn the grease nipple one turn to the
left to release grease and reduce track
chain tension.
• Use a grease gun to add grease to tighten
the track chain.
It is also important to look at parameters of
the excavator, such as total hours of travelling
versus digging, and total hours travelled in
high-speed mode versus in low-speed mode.
Torque settings on all undercarriage bolts
should also be checked, including roller and
top idler brackets, track shoes, sprockets, and
final drives. n
SEPTEMBER 2017
27