BOOM GRT880 SERVICE MANUAL
4-52
Published 10/19/2017, Control # 618-00
acceptable. If the cables do not make a slapping noise under
these conditions, it is an indication that the extension cables
may be too tight and should be readjusted. Be aware that
there may also be a similar noise made by the telescope
cylinder rod mount at the rear of the base section and center
mid section and confusion between the two could be
experienced.
NOTE: The extension cables must be adjusted properly
before the retract cables can be adjusted.
1. Extend and set the outriggers, ensuring the crane is
level.
2. Ensure the boom is over the front and at a horizontal
position (boom angle elevation 0 degrees or lower).
3. Extend boom until the front end of the lower telescope
cylinder is accessible through the holes in tele 1 and 2.
4. With the front of the boom in the above position, extend
the boom approximately 25 mm (1 in) to relieve the
tension in the retract cables. Access the retract cables
from the front of the boom nose and view the slack of the
retract cables through the hole in the back plate of the
boom nose. Using the nuts on the retract cables, remove
slack evenly, until both retract cables are at least 25 mm
(1 in) above the lower leg of the cable retainer bars on
the sheave mount on the upper telescope cylinder.
5. Retract the boom approximately 25 mm (1 in) to relieve
tension on the extension cables. Shut down the crane.
Evenly tighten the swivel nuts on the adjusting bolts,
until the extension cables are up 150 mm (6 in) off the
top of the bottom pad plate at the back of tele 3. Look
through the holes in the boom sections to see the slack
in cables.
6. Lock the adjustments with the jam nuts.
7. Extend the boom until tele 2 and 3 extend several
centimeters (inches).
8. Adjust retract cables so that tele 3 stop block bottoms
out 3 to 4 mm (0.12 to 0.19 in) before the stop block tele
2 bottoms out.
9. If stop block on the tele 3 cannot be properly adjusted
without excessive thread 32 mm (4.5 in) protruding out
from the jam nuts, loosen the nuts on the retract cables
25 mm (1 in), and loosen the swivel nuts 25 mm (1 in).
10. Adjust retract cables until stop block on tele 3 bottoms
out properly. Install jam nuts.
11. If the retract cables can still not be adjusted properly,
remove all the tension in the retract and extension
cables and return to step 4. In step 5, adjust the
extension cable to 127 mm (5 in) and continue with
procedure.
NOTE: If grease fittings are not fully accessible at full
boom extension, make the following adjustments.
12. Retract boom approximately one foot and tighten extend
cables one full turn each.
13. Extend boom to make sure grease fittings line up with
hole. If not lined up with hole, retract boom slightly and
add one additional turn on each of the extend cables.
14. Once grease fittings line up with boom at full extension,
fully retract boom at high speed. When boom initially
begins to retract, extension cables should become slack
enough to hit the boom section. If this does not happen,
reduce tension on retract cables until they do become
slack.
15. Just as the boom begins to bottom out, observe that tele
3 still bottoms out before tele 2. If so, all adjustments are
correct.
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