Manitowoc National Crane 800D, Operator'S And Service Manual

Page: 155 / 256

National Crane
Published 5-27-2018 Control # 039-06 6-5
800D REPAIR
THREE 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, 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
l o c at e d o n t h e i n s i d e r e a r o f th e 2 n d s e c t i o n ar e
accomplished as follows:
1. Extend boom until grease access hole becomes visible
in side plate of 2nd section as it extends out of 1 st
section.
2. Visually check alignment between the 2nd section
access hole and the access hole in 3rd section. When
these holes become aligned, the end of the retract cable
sheave pins will be visible and accessible for lubrication.
3. This boom extended position will coincide with proper
alignment of the access hole in the rear of the 1st
section for lubrication of the retract sheaves attached to
the rear of the 2nd section.
4. The sheaves located on the boom tip end at the
telescope cylinder can be greased while the boom is
fully retracted. Access to the grease holes on either end
of the pin is through holes in the boom side plates.
Three 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 telescope cylinder butt plate, and the
third section should be bottomed on the thick vertical
side plates welded to the inside of the second section.
(See reference dimensions below)
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.
4. Torque retract cables to 14 lb-ft (19 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.
5. Torque extend cables to 20 lb-ft (27 Nm). Cable
adjustment point is located at the rear of the boom on
the cable anchor bar going through the hoist mount.
6. Repeat steps 4 and 5. Torque the retract cables to 14 lb-
ft (19 Nm). Torque the extend cables to 40 lb-ft (54 Nm).
7. Cycle the boom fully, check that all cables are torqued
properly and that all sections are retracted completely,
then add jam nuts to all cables. All threaded cable ends
must be equipped with retainer nuts, jam nuts and cable
protectors.
3RD STAGE
2ND STAGE
1ST STAGE
10.88
24.94
9400
Fo
r
Reference
Only