User's Manual

46 Revision 2 GM550 v1043 FCC-IC.doc
Boom Deflc: 0.0
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change value
Radius Display Troubleshooting
For accurate radius calculation the actual boom length and angle, and the jib length and angle
must be correctly displayed by the GS550 and all radius parameters must be correctly measured
and entered in the radius settings of the GS550 display. Before proceeding with troubleshooting
confirm that all steps described at the beginning of the Radius Calculation section, including the
radius parameters subsection, have been followed. The most common reason for error is caused
by incorrect slew offset compensation. If the difference between the radius displayed and the
actual radius remains constant through all boom angles and boom lengths the slew offset should
be adjusted accordingly.
Boom Deflection
Some booms bend significantly with a load on the hook, thus reducing effective radius. Boom
deflection can be verified if the displayed radius is equal to the actual radius with the boom at
0° and at 90° but greater at a boom angle of 45° (boom deflection is greatest at 45°).
Furthermore, the effect of boom deflection is greater when the boom is longer. To
compensate for boom deflection, adjust the boom deflection value in the radius settings of
the GS550. Follow the steps below to determine the appropriate boom deflection
compensation value.
Step 1) Raise the boom to 45° with a known load.
Step 2) Compare the radius displayed with the actual radius. Change the boom deflection
compensation value and again compare the radius displayed with the actual radius. Adjust
the boom deflection value until the radius displayed equals the actual radius.
Tip: with the boom at 45° and the maximum load on the hoist, the boom deflection compensation
value should equal the difference in feet between the radius displayed and the actual radius. With
the boom at 45° and half the maximum load on the hoist, the boom deflection compensation value
should equal twice the difference in feet between the radius displayed and the actual radius.
No Load Deflection
The "No load deflection" value (menu 4C7) permits compensation for booms that deflect
significantly under their own weight, even with no load on the hoist. This value should not be
adjusted unless so advised by LSI technical support.