National Crane Published 10-30-2014 Control # 040-09 5-19
1400H OPERATOR AND SERVICE MANUAL SERVICE
FOUR SECTION BOOM MAINTENANCE
Do not, under any circumstances, work at an
elevated height without using proper fall protection as
required by local, state or federal regulations.
Internal Cable Sheave Lubrication
Special Tools: Nozzle or needle grease gun fitting. The
lubrication points on the sheaves are not equipped with
grease fittings (zerks), therefore a 0.25 in (6,35 mm)
diameter nozzle grease gun tip will be required. Contact the
National Crane Product Support Department to obtain this
nozzle tip (NCC PN 955047), or numerous variations of the
nozzle tip can be purchased at local hardware or auto parts
retail outlets.
NOTE: Observation through the sheave case for the
extend sheaves and the hoist mount for retract sheaves
will visually determine the amount of grease necessary
for proper lubrication. A slight amount of grease
extrusion around the pin joint is adequate for proper
lubrication.
Lubrication of the extend cable sheaves located on the
boom tip end of the extend cylinder, and the retract cable
sheaves located on the inside rear of the 2nd and 3rd section
and the extend cable sheave attached to the bottom of the
top plate of the second section at the sheave case end of the
boom, are accomplished as follows:
1. Extend boom 78 in (198 cm) per section or 19.50 ft (594
cm) for a four section boom.
2. Visually check alignment between the grease access
holes for the retract sheaves, when the holes align, the
end of the extend cable sheave pin will be accessible
thru a hole in the 3rd section side plate for lubrication.
3. Grease all pins accessible at this boom length location
with nozzle grease gun fitting.
4. The extend cable sheave located on the bottom of the
top plate of the 2nd section at the sheave case end of
the boom can be accessed at any boom length for
lubrication.
Four Section Cable Tensioning
After boom reassembly or from time to time if interior
proportioning cables appear loose, cable tensioning may be
required. Tensioning must be done with the boom horizontal.
1. Slightly tighten all cables. Then cycle the boom
approximately 4 ft (120 cm) out and in a few times to
equalize the extend and retract cable/boom section
sequence positioning.
2. Fully retract boom. Do not induce and hold hydraulic
pressure. At full retraction, observing through the hoist
mount end of the boom, the second section should be
bottomed on the extend cylinder butt plate, the third
section should be bottomed on the thick vertical side
plates welded to the inside of the second section, the
fourth section should be bottomed on the thick vertical
side plates welded to the inside of the third section.
3. It is important to achieve these boom section positions
before torquing. If the boom sections do not bottom out
as specified (boom is out of sequence), adjust cables to
achieve proper section positioning. After proper section
position has been established, a scribe mark on all the
sections at the boom tip end to identify proper section
position relative to each other may be helpful during the
tensioning process.
4. Torque 4/3/2 retract cables to 7 lb-ft (9,5 Nm). Cable
adjustment point is located at the sheave case end of
the boom, on the bottom of the 2nd section. Use the flats
at the front of the cable ends to keep the cables from
turning while torquing retainer nuts.
5. Torque large extend cables to 22 lb-ft (29,8 Nm). Cable
adjustment point is located at the rear of the boom on
the cable anchor located in the rear of the 2nd section.
6. Torque 3/2/1 retract cables to 9 lb-ft (12,2 Nm) Cable
adjustment point is located at the sheave case end of
the boom, on the bottom of the 1st section. Use the flats
at the front of the cable ends to keep the cables from
turning while torquing retainer nuts.
7. Torque 1/2/3 extend cable to 9 lb-ft (12,2 Nm) Cable
adjustment point is located at rear of boom, on the hoist
crossbar spanning the 1st section.
8. Repeat steps 4, 5, 6, and 7, torquing the 4/3/2 retract
cables to 14 lb-ft (19 Nm). Torque the large extend
cables to 45 lb-ft (61 Nm). The 3/2/1 retract cables to
18 b-ft (24 Nm) and the 1/2/3 extend cable to 18 lb-ft
(24 Nm)
9. Cycle the boom fully, check that all cables are torqued
properly and that all sections are retracted completely,
utilizing scribe marks or bottoming position of boom
sections then add jam nuts to all cables. All threaded
cable ends must be equipped with retainer nuts and jam
nuts.
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