National Crane 600H, Service Manual

Page: 101 / 232

NATIONAL CRANE
08-19-2022 Control # 092-13
4-27
600H SERVICE MANUAL BOOM
4
4. Using an overhead hoist, lift the jib assembly and align
and pin the jib to the boom sheave head.
5. With jib pinned to the sheave head, swing the jib parallel
to the boom and install the pin which keeps the jib from
swinging (the pin is attached by cable to the end of the
jib).
.
6. Slowly retract the boom until the jib ears are within 0.50
in (13 mm) of the ear assemblies on the first section.
Observe the vertical alignment of the jib ears and ear
assemblies and add or remove shims until the jib is
supported by the jib ears. The jib will typically rest only
on the upper support.
7. Observe the horizontal alignment of the slot in the ear
assemblies and the alignment pin in the jib. Horizontal
adjustment of the stow ears is provided by oversize bolt
holes in the stow ear. Move the ears in or out to achieve
proper alignment. Position the top ear so it holds the top
of the jib in toward the boom and the bottom ear so that it
holds the bottom of the jib away from the bottom of the
boom.
8. Retract the boom slowly. Observe the stow hook and
side stow bracket assembly alignment as the boom is
retracted (View AA and BB below).
9. When the boom is fully retracted, the jib must be
bottomed out securely in the ear assemblies. If the
alignment pins are not aligned properly, the hook
assembly and front bars will have to be positioned as
shown so the jib cannot slide forward or backward as the
boom is elevated.
10. Try to remove the jib pins. If the pins are too tight, the
stow hook assembly or front bars will have to be
adjusted.
11. Torque all capscrews to their specified torque value,
refer to Fasteners and Torque Values pg 1-7. Install stow
pin in lock assembly and remove the jib pins.
12. Extend and retract boom to insure proper alignment of
jib pins.
13. Install jib pins and remove the stow pins.
14. Extend and retract the boom and jib to ensure proper
alignment of jib stow brackets.
FIGURE 4-17
Shims
Jib Ears
Upper Support
Lower Support
FIGURE 4-18
Alignment Pin
FIGURE 4-19
CAUTION
Make sure ramp slides up to the stow hook and does not
hit the end of the ramp.
Stow Hook
on Boom
Stow Pin
Ramp Side Stow
Bracket on Jib
Alignment
Pin
FIGURE 4-20
Front Bar
(Top & Bottom
Acceptable
Not
Acceptable
FIGURE 4-21
REFERENCE ONLY