BOOM
RT765E-2 SERVICE MANUAL
4-16
Published 9-04-2014, Control # 422-08
BOOM EXTENSION AND RETRACTION
CABLE
Maintenance
NOTE:
For more detailed information concerning
maintenance of the extension and retraction
c a b l e s , r e f e r t o W I R E R O P E i n S e c t i o n 1 -
INTRODUCTION.
Inspection
T h e f o l l o w i n g i n f o r m a t i o n i s ta k e n f r o m a N a t i o n a l
Consensus standard as referenced by Federal Government
Agencies.
All wire rope will eventually deteriorate to a point where it is
no longer usable. Wire rope shall be taken out of service
when any of the following conditions exist.
1.
In running ropes, six randomly distributed broken wires
in one lay or three broken wires in one strand in one lay.
2.
Wear of one-third the original diameter of outside
individual wires. Kinking, crushing, bird caging, or any
other damage resulting in distortion of the rope
structure.
3.
Evidence of any heat damage from any cause.
4.
Reductions from nominal diameter of more than:
•
0.016 in (0.4 mm) for diameters up to and including
0.3125 in (8 mm).
•
0.79 mm (0.031 in) for diameters 0.375 and 0.5 in (10
and 13 mm) inclusive.
•
1.19 mm (0.047 in) for diameters 0.5625 to 0.75 in (14 to
19 mm) inclusive.
•
1.59 mm (0.063 in) for diameters 0.875 to 1.125 in (22 to
29 mm) inclusive.
•
2.38 mm (0.094 in) for diameters 1.25 to 1.5 in (32 to 38
mm) inclusive.
5.
In standing ropes, more than two broken wires in one lay
in sections beyond end connections or more than one
broken wire at an end connection.
Adjustment
At near fully extended boom length, during sudden extension
after retracting the boom some distance, and with high
telescoping speeds, the extension cables may slap the
inside of the boom section. This will make a somewhat
audible noise, however this will not cause any damage and is
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
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).
3.
With inner mid extended and the outer mid retracted,
extend the boom approximately 6 in (15 cm). This will
cause a slack condition in the retract cables.
4.
Tighten the retract cable adjusting nuts at the front of the
fly section to approximately 1.0 lb-ft (1.4 Nm).
5.
Extend the boom approximately 6 in (15 cm) and then
retract the boom completely. This will create the loosest
condition for the extension cables.
6.
Using the adjusting nuts on extension cable ends, adjust
the cables so they are approximately 0.56 in (15 mm) off
the top of the telescope cylinder.
NOTE:
Step 6 should be performed with the boom
horizontal and by visually looking through the back
of the base section or through the access holes on
the base section.
7.
Lock the adjustments with the jam nuts.
NOTE:
During retract cable adjustments, the inner mid
section must remain fully extended.
8.
Extend the boom until the outer mid/fly extends several
cm (in).
9.
Retract the boom until either the fly section just contacts
the outer mid stop block or the outer mid section just
contacts the inner mid stop block.
10.
Check the gap between the stop blocks and the boom
sections. If there is a gap between the inner mid
section’s stop block and the outer mid of more than
0.125 in (3 mm), loosen the retract cable. If there is gap
between the outer mid section’s stop block and the fly
section, tighten the retract cable slightly.
CAUTION
Wear gloves when handling wire rope. Moderate to minor
injury may result if using bare hands.
CAUTION
When adjusting cables, hold the cable end and turn the
nut. Do not turn cable. Turning the cable while adjusting
will result in damage or failure of the cable.
Reference Only
