Manitowoc Published 10-01-12, Control # 044-05 v2 3-33
777 OPERATOR’S MANUAL OPERATING CONTROLS AND PROCEDURES
3
drum brake with brake pedal to stop load and release
drum handle to off.
8. To lower load, leave drum handle in off and release drum
brake with brake pedal to lower load at desired speed.
As load nears desired position, slowly apply drum brake
to slow down load. Then fully apply brake to stop load
and to hold it in position.
NOTE: There is no power lowering feature in free fall. If a
drum handle is moved forward from off while free
falling a load, corresponding band brake will apply.
9. If load will be suspended for any length of time, fully
press and latch brake pedal in applied position, turn on
drum park, and engage drum pawl.
Clamshell Operation
Preparing for Clam Operation
1. Turn off free fall for both drums. The drums will operate
in full-power.
2. Select and confirm CLAMSHELL mode.
3. Disengage drum pawl for both drums.
4. Set engine speed at desired rpm.
5. Adjust clam closing pressure as follows:
a. Raise bucket off ground.
b. Unlock, press and hold limit bypass switch.
c. Press digital display selector to set closing line
pressure. The CLAM CLOSING PRESS screen will
automatically appear on the digital display.
Press top end of display selector (scroll up) to
increase pressure; press bottom end of display
selector (scroll down) to decrease pressure.
With the bucket raised off the ground (on holding
line) at the start of the clam cycle, adjust clam
closing pressure so bucket fully closes and just
starts to rise on closing line.
Readjust pressure as required while digging so
bucket fully closes without rising on closing line.
NOTE: The clam closing pressure selected will remain in
computer memory even after engine is stopped.
Bucket size, parts of line, and type of material being
handled govern clam closing pressure required. It
may be necessary to readjust clam closing
pressure if any of these factors change.
Operating Clamshell In Full-Power
Perform steps described in Preparing for Clam Operation.
Then proceed as follows:
Closing Bucket (Digging)
1. Lower bucket into digging area.
2. Pull back closing line handle to close bucket. The
holding line will pay out automatically allowing the
bucket to dig in as it closes.
3. Release closing line handle to off when bucket is closed
fully.
NOTE: Watch closing line when digging in a blind area.
Bucket is closed when closing line stops moving (if
clam closing pressure is properly adjusted).
Raising Bucket
1. Pull holding line handle back to raise bucket at desired
speed.
2. Swing to dumping area as bucket rises.
3. Release holding line handle to off when bucket is at
desired height.
Dumping Bucket
1. Push closing line handle forward to dump bucket at
desired speed.
2. Release closing line handle to off as soon as bucket is
empty and fully open.
Use care not to slacken closing line while dumping. Any
slack in closing line will have to be taken out while
digging. This action will slow down clam cycle.
Lowering Bucket
WARNING
Falling Load Hazard!
When operating in free fall, load will lower uncontrolled if
drum brake is not applied with brake pedal when drum
handle is released to off.
Be ready to apply drum brake so lowering speed can be
controlled and load can be stopped immediately when
necessary.
CAUTION
Machinery/Boom Damage!
While free falling a load:
• Do not move drum handle in either direction from off.
• Do not turn off free fall.
• Do not turn on drum park.
Shock load damage to machinery or boom can result.
Bring drum to a complete stop with brake pedal before
performing above operations.
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