National Crane 600H, Service Manual

Page: 76 / 232

BOOM 600H SERVICE MANUAL
4-2
08-19-2022 Control # 092-13
THREE SECTION BOOM OPERATION
A rod-fed, double-acting cylinder, attached to the 1
st
and 2
nd
boom sections, supports and propels the 2
nd
boom section.
The extend cables attach to the base end of the 1
st
boom
section, are reeved around sheaves attached to the cylinder,
and attach to the base end of the 3
rd
boom section, providing
support and extension the 3
rd
boom section.
The retract cables attach to the tip end of the 1
st
boom
section, are reeved around sheaves attached to the 2
nd
boom section, and attach to the base end of the 3
rd
boom
section, therefore providing retraction of the 3
rd
boom
section. This type of boom operation provides that the 2
nd
and 3
rd
section booms extend and retract equally. Proper
service and maintenance is required to insure smooth and
proper operation.
Special Boom Inspection
If the boom has not been disassembled and inspected in the
last seven years or 3,000 hours of use, the boom is to be
completely torn down to allow a thorough inspection of the
extend and retract cables, sheaves, and pins.
THREE SECTION BOOM MAINTENANCE
Three Section Cable Tensioning
After boom reassembly or from time to time if interior
proportioning cables appear loose, cable tensioning may be
required. For more information, see “Cable Tensioning” on
page 4-16.
Item Component
1 Extend Cable Adjustment
2 Section 1
3 Retract Cable
4 Retract Cable Adjustment
5 Extend Cable Anchor
6 Retract Anchor
7 Section 2
8 Section 3
9 Tip
Item Component
FIGURE 4-1
REFERENCE ONLY