Manitowoc 999, Service And Maintenance Manual

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Reference
Only
Manitowoc
Published 05-16-17, Control # 233-03
4-7
999 SERVICE/MAINTENANCE MANUAL BOOM
4
PHYSICAL BOOM STOP
The physical boom stops ( Figure 4-3 ) serve the following
purposes:
• Assist in stopping the boom smoothly at any angle
above 81°
• Assist in preventing the boom rigging from pulling the
boom back when traveling or setting loads with the
boom at any angle above 8°
• Assist in moving the boom forward when lowering the
boom from any angle above 81°
• Provide a physical stop at 90°
The telescopic struts between the boom stops and the boom
butt have two positions:
• WORKING POSITION (struts extended). The physical
boom stops must be in this position for all crane
operations.
• SHIPPING POSITION (struts retracted). This position
provides maximum clearance for shipping the boom butt
with the physical boom stops installed.
See Crane Assembly/Disassembly in Section 4 of 999
Operator Manual for instructions on raising and lowering
physical boom stops.
Operation
See Figure 4-3
When boom is raised to 81°, springs in boom stop tubes
begin to compress.
As boom is raised higher, spring compression increases to
exert greater force against boom.
If for any reason boom is raised to 90°, boom stop springs
fully compress to provide a physical stop.
WARNING
Physical boom stops must be installed and pinned in
working position for all crane operations.
Physical boom stops do not automatically stop boom at
maximum operating angle. Automatic boom stop must be
installed and properly adjusted.