National Crane 1-21-2019 Control # 104-07 4-11
1400A SERVICE MANUAL BOOM MAINTENANCE
11. Install 4
TH
section retract cable button end into anchor
point in 4
TH
section.
• Install keeper plate and capscrews.
• The keeper plate is installed temporarily to keep the
button ends in place during this phase of the
assembly. It needs to come back out during cylinder
and 4
TH
section extend cable installation. Coil the
4
TH
section retract cables temporarily into 5
TH
section.
12. Assemble top rear wear pads with the cam plates to the
top of the 5
TH
section.
To adjust the wear pads, rotate the wear pad and
plate together or separately end for end. The wear
pad can be adjusted over a range of 4.8 mm (3/16
inch).
This is possible because the holes in these parts
are offset from the center. The holes are 1.5 mm
(0.06 inch) off center in the plate and 0.8 mm (0.03
inch) off center in the wear pad.
13. Pull threaded ends of 5
TH
section retract cable under the
4
TH
section towards front of boom.
14. Position the 4
TH
-5
TH
section assembly in front of
3
RD
section. Route the 5
TH
section retract cables to allow
easy cable movement as the sections slide together.
15. Slide 4
TH
-5
TH
assembly into 3
RD
boom section about 90
cm (36 inches). Keep 4
TH
-5
TH
assembly suspended to
avoid damage to 5
TH
section retract cables.
16. Assemble bottom wear pads on 3
RD
section pad plate.
Raise 4th-5th assembly high enough to allow the plate
with the pads to slide between the sections
• Place retract cables in the grooves in the bottom
pad plate. As the boom sections are slid together,
the retract cables are pulled through the grooves
• Fasten the pad plate to the bottom of the 3
RD
section
with the appropriate hardware
17. Install a nut on the threaded ends of the 5
TH
section
retract cables, to keep the cable ends from pulling
through the anchor as the sections are pushed together.
18. Push the 4
TH
-5
TH
assembly inside the 3
RD
section, until it
is within 90 cm (36 inches) of full insertion.
19. Install side wear pads with appropriate shims on front
inside of the 3
RD
section boom. Install upper spacer bar
and cable guide with wear pad and related hardware on
the top to the 3
RD
section. Shim according to calibration
instructions, or as pads were originally removed and
tagged.
20. Slide 4
TH
-5
TH
assembly inside 3
RD
section until the end of
the 4
TH
section hits against the doubler bars in the 3
RD
section. Use caution as the 5
TH
section retract cable
threaded end gets close to the grooves in the lower front
pad plate and adjust as necessary to allow proper
placement. A scribe mark on the 4
TH
section at full
retraction aids in cable tensioning for proper boom
sequence later.
21. Assemble top rear wear pads with the cam plates to the
top of the 4
TH
section. See step # 12 for pad installation
detail.
• Uncoil 4
TH
section retract cables from of the 5
TH
section.
• Install the 3
RD
section retract sheaves and pins
inside the rear of the 3
RD
section with the proper
hardware and loctite 243.
• Reeve the cable over the sheave installing upper
keeper capscrew and lower rear pad. This pad
serves as a cable keeper and a lower and side pad
for the rear of the section.
22. Pull threaded end of 4
TH
section retract cables, which
are now under the 3
RD
section, towards front of boom.
23. Assembly step 22 completes the -3
RD
-4
TH
-5
TH
boom
assembly. At this point the hydraulic extension cylinder
and related cables and components are inserted into the
3
RD
-4
TH
-5
TH
section assembly starting with step 24.
24. Support extension cylinder in a workable location and
install the 3 extend sheaves in the sheave case end of
the cylinder. Position the pin so that the bearing grease
holes are on the unloaded side of the pin (towards
cylinder butt plate).
• Slide the pin in through the round area of keyway
shaped slot.
• Install the sheaves one at a time as the pin is
inserted through the sheave case.
• Align the slots in the pin with the square keyway
side plate cut outs and push pin/sheaves towards
cylinder butt plate into slot.
25. Install three 4
TH
section extend cables over the sheaves
• Place the button end through opening between the
sheave and the front double tapered plate on the
cylinder.
• After the cables are in place, install the plastic
tapered cylinder pads on the top and bottom
shelves of the cylinder sheave case.
• Apply loctite and jam nuts in these locations. The
pads, when secured in place, act as cable retainers
and wear pads.
26. Pull the three button ends through the extend cylinder
sheave case until there is enough slack to install the
4
TH
section extend cable anchor.
Fo
r
Reference
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