Manitowoc Published 11-20-19, Control # 234-19 3-67
MLC300 OPERATOR MANUAL OPERATING CONTROLS AND PROCEDURES
OPERATING PROCEDURES
VPC Operation
The Variable Position Counterweight system automatically
moves the crane counterweight in and out in response to
changes in boom angle, luffing jib angle, and load conditions.
The amber strobe lights on the counterweight tray flash and
an alarm sounds intermittently when the counterweight is
moving.
During counterweight movement, it is normal for the control
system to temporarily reduce the speed of the following
functions:
• Boom hoist
• Luffing hoist
• Load drums
The control system continuously monitors counterweight
inputs to determine the location of the counterweight. If the
control system cannot move the counterweight to the target
position quickly enough, the system will reduce the speed of
the function causing the change in load moment. For
example, if the counterweight needs to move toward the rear
of the crane, operations increasing load moment — hoisting
up, booming down, or luffing down — will be limited.
Drum speed and VPC movement can be monitored in the
Crane Operation Status Bar of the Main Display Working
Screen. See Figure 3-17
.
For travel on grade, the VPC Lockout Key Switch (page 3-
20) must be in the LOCK position. See step 4 on page 3-81.
Current production cranes are equipped with a Capacity
Chart Information Screen in the RCL/RCI Display. The
Capacity Chart Information Screen allows the operator to:
• view crane capacities (published or modified) and
• in the VPC configuration only, to move the counter-
weight to a desired locked position and handle loads
from a modified capacity chart.
The counterweight can be locked when the crane is in
the VPC-MAX configuration, but a modified chart is not
provided.
For Capacity Chart Information Screen instructions, refer to
the following publications located at the end of this section:
• RCL/RCI Operation Manual
• Locked VPC Operation Manual
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