OPERATING CONTROLS AND PROCEDURES MLC300 OPERATOR MANUAL
3-78
Published 11-20-19, Control # 234-19
Clamshell Operation
For clamshell operation, the crane must be equipped with
Drums 2 and 3:
- Drum 2 is the closing line
- Drums 3 is the holding line
Preparing For Clamshell Operation:
1. Select the desired Clamshell/Duty Cycle Capacity Chart
in RCL/RCI display.
2. Enable the clamshell mode in the Main Display. This
step can only be performed after the capacity chart is
selected in step 1
.
3. Turn off the drum park for both drums.
4. Set engine speed at the desired rpm.
5. Clam closing pressure is set automatically.
Clamshell Operation In Full-Power
Perform Preparing for Clam Operation steps. Then proceed
as follows:
CLOSING BUCKET (Digging)
1. Lower the bucket into the digging area.
2. Pull back the closing line handle to close the bucket. The
holding line will pay out automatically allowing the
bucket to dig in as it closes.
3. Release the closing line handle to off when the bucket is
closed fully.
NOTE Use care when digging in a blind area. The bucket is
closed when the holding line starts to slacken.
RAISING BUCKET
1. Pull the holding line handle back to raise the bucket at
the desired speed.
2. Swing to the dumping area as the bucket rises.
3. Release the holding line handle to off when the bucket is
at the desired height.
DUMPING BUCKET
1. Push the closing line handle forward to dump bucket at
the desired speed.
2. Release the closing line handle to off as soon as bucket
is empty and fully open.
Use care not to slacken the closing line while dumping.
Any slack in the closing line will have to be taken out
while digging. This action will slow down the clam cycle.
LOWERING BUCKET
1. Push the holding line handle forward to lower the bucket
at the desired speed.
2. Control the lowering speed by slowly moving the holding
line handle toward off.
NOTE Lowering speed is controlled by handle movement. It
is not necessary to apply the working brakes to slow
down the bucket during full-power clamshell
operation.
3. Swing back to the digging area as the bucket lowers.
4. Stop swinging when the bucket lands in the digging
area.
5. The bucket will stop lowering automatically when it
contacts ground.
6. Release the holding line handle to off.
7. Repeat the clam cycle.
NOTE Clamshell operation can also be performed with free
fall enabled for both drums.
With clamshell enabled, the free fall brakes will
release only when the closing line handle is pushed
forward. The free fall brakes for both drums are
released at this time. Full power dumping of the
bucket is not possible with free fall enabled.
If the holding line is operated in free fall, the closing
line must also be operated in free fall; otherwise, the
closing line will not keep up with the holding line and
the bucket will close while lowering.
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