National Crane Published 08/16/19 Control # 112-05 4-11
500E2 SERVICE MANUAL BOOM
3- Section Boom w/ 1 Stage Cylinder Cable Positioning
Cable Tightening Sequence 3 Section Boom with (1)
Stage Extend Cylinder
Boom must be in horizontal position when adjusting cable
tension (See Figure 4-2.) Retract boom fully ensuring
sections are bottomed out on section stops. Ensure all
sections are fully bottomed out and do not spring
back.(Reference Tensioning Setup Procedure)
321 and 123 cable balancing
Extension
1. Measure the extension gaps between the first and
second section and the second and third section.
If the extension gap between second and third section is less
than the extension gap between the first and second section.
2. Tighten 123 extend cable located at the back top of the
base section the difference in the extension gap
measurements.
3. Extend and retract the boom a few times and then
repeat measuring the extension gaps.
The third section should have moved out.
4. Tightening until the extension gap between the first and
second section and the extension gap between the
second and the third are equal.
Retraction
1. Measure the retraction gaps between the first and
second section and the second and third section.
If the retraction gap is greater between the second and
third section than the retraction gap between the first
and second section;
2. Tighten the 321 retract cable located at the front bottom
of the base section the difference in the retraction gap
measurements.
3. Extend and retract the boom a few times and then
repeat measuring the retraction gaps.
The third section should have moved in.
4. Tightening until the retraction gap between the first and
second section and the retraction gap between the
second and the third are equal.
At this time the all extendable sections should extend
and retract equally and bottom out against the stops
simultaneously.
8860-4
FIGURE 4-2
EXTEND CABLE
RETRACT CABLE
3RD SECTION
2ND SECTION
1ST SECTION
BASE
TIP
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