2-28. Operation of Crane Front End Attachment
j. Swing revolving frame to spot for next load
a. Perform preventive maintenance checks and
services (para 3-6); start engine (para 2-10); engage
k. Repeat steps a through j cycle as necessary.
engine clutch (fig. 2-24), then raise boom (if necessary)
l. Disengage engine clutch (fig.
2-24); stop
(para 2-12c.).
engine (para 2-11), then perform preventive
b. Lower hook block by releasing pressure on the
maintenance checks and services (para 3-6).
digging (main hoist) brake pedal; moving crowd and
retract clutch lever away from operator (fig. 2-23), and
2-29. Operation 6f Clamshell Front End Attachment
allow hook block to drop slowly to center of load to be
a. Perform preventive maintenance checks and
lifted. Swing revolving frame (para 2-12b), or travel
services (para 36); start engine (para 2-10), then engage
craneshovel (para 2-12d) when necessary to center
engine clutch (fig. 2-24).
hook over load.
b. Raise the open clamshell bucket from ground by
c. When hook block is in desired position, return
releasing digging brake pedal and hoist brake pedal (fig.
crowd and retract clutch lever to neutral, apply main
2-24), and at the same time pulling back on the crowd
hoist (digging) brake pedal and hold.
and retract clutch lever and the hoist and propel clutch
d. After load is safely attached, allow ground crew
lever.
to clear load, then pull back on crowd and retract clutch
Note
lever (fig. 2-23), at the same time release main hoist
The above clutch levers are side-by-
(digging) brake pedal.
side, and may be controlled with one
e. When load is sufficiently high to swing safely,
hand, if desired. If the clamshell
return crowd and retract clutch lever to neutral position,
bucket starts to close in mid air,
and at same time apply main hoist (digging) brake pedal
release pressure on crowd and
to hold load in position.
retract clutch lever just enough to
reopen bucket.
c. When bucket is high enough to clear
2-12b).
obstructions, return crowd and retract and hoist and
Note
propel clutch levers (fig. 2-24) to neutral and at the
Engage swing and propel clutch
same time apply digging and hoist brake pedals to hold
lever (fig. 2-23) slowly so that swing
open bucket in position.
motion will start and stop smoothly.
g. Lower load by moving crowd and retract clutch
2-12b).
lever away from operator releasing main hoist (digging)
brake pedal, and control rate of load descent by varying
e. Release digging brake pedal and hoist brake
the pressure applied to main hoist (digging) brake pedal.
pedal and lower open clamshell bucket to stockpile.
When load is in proper position, move crowd and retract
The rate of bucket descent is controlled by pressure on
clutch lever to neutral and apply main hoist (digging)
hoist brake pedal. Allow closing (digging) line to run
brake pedal.
free when lowering bucket.
Note
Note
If it is necessary to unload at a
If necessary to force bucket teeth
greater or lesser radius, the boom
into hard material, a long fast drop of
may be raised or lowered as required
bucket from tip of boom to stockpile
will do the job.
traveled (para 2-12d). If boom is
f. As soon as bucket enters material, apply digging
lowered, load must be hoisted
and hoist brake pedals to prevent cables overrunning.
simultaneously to prevent load from
g. Release digging brake pedal, and at the same
lowering too fast and causing
time pull crowd and retract clutch lever toward operator
damage. If traveled for less than 100
to close the bucket. To adjust digging depth, slack off
feet, it is not necessary to put idler
on hoist brake pedal as bucket closes and digs into
sprockets under boom foot.
material.
h. When load is solidly at rest, release main hoist
h. When bucket is closed, pull the hoist clutch
(digging) brake pedal and give ground crew slack to
lever toward operator, and at same time release hoist
unfasten hitch.
brake pedal. As bucket rises it may be necessary to
i. When load is unhitched, pull back crowd and
slack off on hoist clutch lever to avoid opening bucket in
retract clutch lever to raise hook block clear, and hold in
mid air.
position with main hoist (digging) brake pedal.
i. Raise bucket high enough to clear obstructions;
Note
release crowd and retract clutch lever and the hoist
Travel, or adjust boom if necessary,
clutch lever, and at the same time apply
in reverse order to change made as a
result of note above.
2-35
