JLG LSS Boom - Manual (Page 52)

SECTION 3 - SERVICE - ELECTRIC POWERED BOOM LIFTS
3-12 – JLG Lift – 3124287
Empty Platform Weight (DIAG-
NOSTICS, PLTLOAD) is not
within +15lbs (±7kg) of zero.
or
Platform Load readings (DIAG-
NOTICS, PLTLOAD) are unsta-
ble by more than +2lbs (±1kg)
(without the influence of vibra-
tion or wind).
or
There are large variations in
Platform Load (DIAGNOS-
TICS, PLTLOAD) based on the
location of the load. Tolerance
to variations is 20lbs for an
evaluation using the techni-
cian’s weight, and +5% of
Rated Load when using cali-
brated weights.
4. Improper procedure was used when tightening the fasteners for the Shear Beam
Load Cells. Failure to regard the notes in the Installation guide can result in large off-
axis forces on the sensors (which disturb the primary measurement axis readings).
Loosen all fasteners and sequentially torque them as recommended in the Installa-
tion guide (new fasteners are recommended to achieve proper torque).
5. Damage to the platform or support structure has occurred or one of the components
is out-of-tolerance (not planar). When the fasteners are torqued to specification, the
sensors are disturbed by large off-axis forces (which disturb the primary measure-
ment axis readings). Loosen all fasteners and observe whether the platform or sup-
port were drawn-up by the fasteners (they should both be planar and match up
accurately). Resolution is to replace the damaged or faulty component. Watch for
Shear Beam Load Cell damage (yield) as a result of this difficulty.
6. One of the Shear Beam Load Cells is contaminated by debris or moisture. Examine
each sensor’s reading using the JLG Analyzer. Proceed to the DIAGNOSTICS, CELL
1-4, LOAD displays and determine if the readings are reasonable and stable (not
changing by more than +2lbs (±1kg) (without the influence of vibration or wind).
Lack of measurement stability is a key indication of contamination. Unplug the
appropriate connector (J5 is CELL 1, J6 is CELL 2, J7 is CELL 3, and J8 is CELL 4)
and inspect for dirt or moisture. Look carefully into the female connector on the sen-
sor’s cordset for evidence of contamination. Debris should be brushed away with a
soft bristle brush (do not introduce any cleaners as they will leave conductive resi-
due). Moisture should be allowed to evaporate or accelerated with a heat-gun (use
low heat and be carefully to not melt connector materials). Moisture intrusion into the
molded portion of the connector (capillary action into the wire bundle) or the Shear
Beam Load Cell itself will require replacement of the sensor.
7. One of the Shear Beam Load Cells has been mechanically damaged (yielded). Any
Shear Beam Load Cell that is physically deformed or has damage to one of the stain-
less steel covers should be replaced immediately. It is also possible to have invisible
mechanical damage resulting from an extreme overload (>6000lbs [>2722kg]). This
can be detected by removing all fasteners that mount the platform and supporting
the platform on two saw-horses or barrels (no weight resting on the Shear Beam
Load Cells). Examine each sensor’s reading using the JLG Analyzer. Proceed to the
DIAGNOSTICS, CELL 1-4, LOAD displays and observe whether the unloaded sen-
sors read with +15lbs (±7kg) of zero (individually). Replace sensors that read exces-
sive force when physically unloaded.
8. The LSS Module is suspect. Interchange the Shear Beam Load Cell connections (J5-
J8) and observe the results via the JLG Analyzer. Proceed to the DIAGNOSTICS,
CELL 1-4, LOAD displays and observe the readings. If the problem seems to remain
with a particular sensor, carefully re-examine the issues above. If the problems
seems to remain with a particular LSS Module channel, substitute another module.
Table 3-3. LSS Troubleshooting Chart - Measurement Performance
Difficulty Possible Resolution