OPERATING CONTROLS AND PROCEDURES 777 OPERATOR’S MANUAL
3-22 Published 10-01-12, Control # 044-05 v2
LIMIT DEVICES
Counterweight Max Up Limit
Prevents over-tensioning the counterweight lifting pendants
when installing counterweights and parking the boom.
If the boom is lowered too far while the lifting pendants are
installed, the counterweight tray rises and trips either limit
switch at the rear of the crane. The computer then stops
boom down operation. The operating limit alert will turn on
and COUNTERWEIGHT MAX UP will appear on the digital
display.
Boom Maximum Up Limit
Automatically stops the boom when it is raised to a preset
maximum angle:
• 83° for Boom without Luffing Jib
• 88° for Boom with Luffing Jib when the boom up limit
can be bypassed.
• 89° for Boom with Luffing Jib when the boom up limit
cannot be bypassed.
The boom can be lowered after the limit is contacted.
Boom Maximum Down Limit (if equipped)
Automatically stops the boom when it is lowered to a preset
minimum angle (usually 0°).
The boom can be raised after the limit is contacted.
The appropriate limit bypass switch must be moved to the
bypass position to lower the boom below the limit.
Block Up Limit
Automatically stops the boom and luffing jib (if equipped)
from lowering and all loads from hoisting if a load contacts a
block-up limit switch.
The load on the corresponding drum can be lowered and the
boom and luffing jib can be raised after a block-up limit
switch is contacted.
The appropriate limit bypass switch must be moved to the
bypass position to hoist a load above the limit.
Luffing Jib Max Up Limit
Prior to Crane S/N 7771156
Automatically stops the luffing jib when the boom to luffing jib
angle is 168°.
The luffing jib can be lowered after the limit is contacted.
For rigging purposes only (when boom and luffing jib are
being raised or lowered from or to ground), the appropriate
limit bypass switch must be moved to the bypass position to
raise the luffing jib above the limit.
WARNING
Avoid Death or Serious Injury!
Read and understand instructions in Crane Assembly and
Disassembly Guide before selecting setup mode or using
setup controls.
WARNING
Falling Boom/Jib Hazard!
If you bypass boom up limit for any reason, DO NOT allow
physical boom stops to bottom out. Boom butt could be
damaged, causing boom and jib to fall over backwards.
Crush Hazard!
Maintain constant communication between operator and
assistant during following steps.
Stay clear of moving parts.
WARNING
Falling Boom Hazard!
When lowering boom below down limit, do so slowly with
extreme caution. Do not lower boom to point where less
than two full wraps of wire rope are on boom hoist drums;
wire rope could be pulled out of drums allowing boom to
fall.
WARNING
Two-Blocking Hazard!
If it is necessary to hoist a load above block-up limit, do so
slowly with extreme caution to prevent two-blocking.
Do not hoist load above minimum block clearance given
on Range Diagram in Capacity Chart Manual.
Do not use limit bypass switch to lower boom or luffing jib
after block-up limit is contacted; two-blocking could occur,
causing load to fall.
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