Basic of construction method using hydraulic excavator

A INDUSTRI & WORLEY PARSONS INDONESIA - BASIC OF CONSTRUCTION METHOD USING HYDRAULIC EXC

When the link stands at 90o to the
cylinder, and the arm cylinder, each
cylinder demonstrates the maximum
dumping force. Therefore you are advice
to make the best use of this angle to
heighten the working efficiency.

The excavation range in terms of an arm
angle is 45o to the front side and 30o to
the rear side. This range will slightly vary
depending on the excavation depth. Do
not attempt to swing the bucket to the
stroke end of the arm cylinder, but
operate the boom and the bucket within
this range.

When excavating soft soil, set the angle of a
bucket bottom plate at an approx 60o ; pull
back the arm to dig the bucket cutting edge
in the ground while lowering the boom; and
scoop earth with the bucket at a time.

• Set the angle of the bucket bottom
plate at an about 60o
(as compared with the case that the bucket
angle is kept free, the working amount
increases by approx. 20%)

Pull back the arm while lowering the
boom, and dig the bucket in the ground
to the depth of 2/3 of its height

Scoop earth in the bucket at a time

When excavating the common natural
ground. set the angle of the bucket
bottom plate at an about 30o; dig the
bucket in the ground to the depth of 1/3 of
its height; pull back the arm horizontally;
while making a fine control of the boom
RAISE; and tilt back the bucket to scoop,
Watching the volume of earth being taken
in.

• The earth excavation resistance is
reduced as the bucket angle is lowered,
which in turn allows more earth to be
taken in the bucket. Furthermore,
smooth excavation help save the fuel.

Set the bucket angle at an about 30o.
(The working amount increase by
approx 20% as compared with the case
that the angle of the bucket bottom
plate is set at 60o).

Pull back the arm and dig the bucket in
the ground to the depth of 1/3 of its
height.

Hold the bucket as dug in the ground at
an angle of 30o by making a fine control
of the boom RAISE, and pull back the arm
horizontally.

Scoop earth in the bucket, watching the
volume of earth being taken in.

When excavating soft rocks and rocks with
many joints, set the angle of the bucket
bottom plate at less then 30o; pull back the
arm while making a fine control of the
boom RAISE; and dig earth as if scraping off
the ground surface thinly.
Meanwhile, if the bucket stumbles on a
hard rock and as a result, the arm htdraulic
oil pressure is relieved, increase the angle
of the bucket bottom plate, keeping the
arm as pulled back (dumping angle at about
60o). Again tilt back the bucket slowly, and
scoop earth as if prying.

When excavating soft rocks and rocks with
many joints, set the angle of the bucket
bottom plate at less then 30o; pull back the
arm while making a fine control of the
boom RAISE; and dig earth as if scraping off
the ground surface thinly.
Meanwhile, if the bucket stumbles on a
hard rock and as a result, the arm htdraulic
oil pressure is relieved, increase the angle
of the bucket bottom plate, keeping the
arm as pulled back (dumping angle at
about 60o). Again tilt back the bucket
slowly, and scoop earth as if prying.

Set the angle of the bucket bottom plate at
less than 30o (10o – 30o)

Pull back the arm, alleviating load, if
necessary, by lifting the arm as the
applied load increases, and scoop
earth as if scraping off the surface
thinly.

If the bucket comes to a halt after
stumbling on a hard rock, tilt the bucket
to an approx. 60o once.

Tilt back the bucket slowly, and scoop
earth as if prying

In backhoe work, too, set the angle of the
bucket bottom plate at less than 30° and
scoop earth as if scraping off the surface
thinly. If the bucket stumbles on a hard rock,
scoop earth as if prying with the bucket, while
keeping the arm as pulled back the same way
as when excavating the flat ground. Excavation
will become easier in this instance if the boom
is lifted then to use its lifting force together.

A. et the angle of the bucket bottom
plate at less than 30o

B. Pull back the arm, lifting the boom
along a slope surface at the same
time, and scoop earth as if scraping
off the slope surface thinly.

C. If the bucket comes to a halt after
hitting a hard rock, tilt the bucket to
approx. 60o

D. Til back the bucket slowly, and scoop
earth as if prying with the bucket.
Excavation will be easier if the boom
is lifted then to use its lifting force
together

There are two different aims in shovel work using a hydraulic excavator. One is to
heighten an excavation efficiency where blasting is restricted and the excavator’s digging
force has to be relied on instead. The other is to serve as a loading machine after blasting
and excavate the natural ground while it is waiting for a dump truck to return.

In shovel work, set the bucket angle in way
that the bucket teeth are nearly
perpendicular. Then pull back the bucket,
keeping the bucket in that posture, and
scoop earth while lowering the boom.

1. Set the bucket at such an angle that
the teeth are perpendicular to the
ground.

2. Pull back the arm, keeping the bucket
at that angle, and scoop earth.

3. If the bucket comes to a halt after
hitting a hard rock, wedge the
bucket teeth in a joint as if prying,
while pressing the bucket against
the slope with the arm. If the
excavation nevertheless does not
work well that way, remove the soft
soil around beforehand to enlarge a
free face and start the excavation.
Now the work should be carried out
easily.

NOTICE:
When a hard rock is struck with the
bucket, it may be loosened and dug out.
However, avoid that practice because that
reduces the loading machine’s durability.

In principle, dig a slope in the work sequence
of (1) through (4) shown at left. When hitting a
hard rock, change the bucket angle and try the
excavation a few times.
In (1) and (2) stages, use both arm force and
bucket force together. At that time, do not
press the bucket against the slope
unnecessarily for fear that the machine front is
lifted. (If the machine front is lifted, it will
fall off with a big shock when load is removed
abruptly.) In stages (3) and (4), press the
bucket against the slope slightly with the boom
and use the machine’s weight for excavation.
At that time, avoid lifting the loading machine
unnecessarily thorough RAISE operation of the
boom.

In an earth pit where it is necessary to
scrape off earth, a loading bench (landing)
has to be formed making use of scraped
earth and rocks. It can be made out in the
following manner.

1. Scraped-off earth and rocks are piled up
at the foot of a slope. When excavating
an upper part of a slope, rocks may
unexpectedly fall off from above and hit
the machine’s undercarriage or the
operator’s cab. To safeguard them,
provide a ditch close to the cutting
surface as (A) shown at left and a
mound as a rock stopper in front of the
machine as (B). Together they assure
safety in the excavation work.

2. Ride the loading machine on the
piled earth and continue excavation
to increase the earth volume.

3. Finally form a loading bench.

In excavating the natural ground, hold the angle of the bucket bottom plate at about
30° and start excavation, pulling back the arm. The arm can exert great force when it is
held nearly perpendicular to the ground. But on the other hand, it is necessary to
control the boom to avoid the arm pressure relief or the machine front from being
extremely lifted.

1. At the beginning of excavation, hold
the arm to 80% of its max. reach.
(Arm excavation force is the lowest
when the arm is at its max. reach,
therefore it is difficult to excavate
under the condition. When excavating
or leveling the ground far ahead of
the loading machine, the work must
be carried out with some tolerance
left in the arm reach.

2. When excavating a ditch wider than the bucket width, swing the
loading machine slightly so as to press the bucket against the ditch wall,
and then carry out excavation.

1. When excavating a ditch as wide as the
bucket width
 Excavation in this instance is carried out
in the work sequence of (1) to (7) shown
at left. In portions (1) and (2), hold the
bucket angle at about 30° and scoop
earth as if scraping off the surface thinly.
If the ground surface is hardened and
the bucket cannot scoop enough earth to
fill the truck body completely at a time,
do not swing the machine and load the
earth, but try again to fill the bucket
completely.

 In portion (3), press the bucket at an
angle of approx. 90° against the front
wall of the ditch; scrape off the wall,
digging the bucket teeth in the earth
until; and when they reach the
specified depth, pull back the arm for
scooping. In portions (4), (5) and (6),
excavate the earth, pulling back the
arm and assisted by the boom force.

 The bottom surface of the ditch is
leveled off at the same time as it is
being excavated. When the surface is
not smooth enough, finish it finely as
(7) shown at left, using the arm and the
boom.

 When finishing the excavation of
portion (6) or (7), extend the arm to its
max. reach; back up the loading
machine so that the bucket cutting
teeth may reach point (A); and park
the machine on the spot. For the
subsequent excavation, follow steps
(4) through (6) explained above.

2. Excavating a ditch 1.5 times as wide
as the bucket width
 First position the loading machine at a
point from where it can excavate portion
(A) shown at left by pulling the arm
straight back and portion (B) by swinging
the machine and pressing the bucket
against the ditch wall.

 The excavation is carried out in the
sequence shown with and (A) and (B)
numbers at left. Meanwhile, keep an
angle of machine’s swing for dumping
excavated earth within approx. 45°, and
a dumping area must be kept within
twice the width of the ditch. (If the
earth dumping area is too far away,
refilling efficiency is lowered.)

3. Earth dumping (when depositing the excavated earth on a ditch side)
 Earth dumping must be continuous, quick and smooth work that is carried out
through a complex operation of swing and boom raise as well as swing and boom, arm
and bucket operation. During the dumping work, limit the boom raise amount to the
minimum, but to the extent that the bucket does not hit a mound of the dumped
earth. That practice ensures a quicker cycle time and lower fuel consumption ratio.

For slope leveling work, use a bucket with a
flat cutting edge. For leveling an
embankment slope, there are two
methods. One is to press the slope surface
with the bucket bottom slightly, and pull
back the arm and lift the boom, keeping
the bucket at a constant angle. The other is
to thinly scrape off the slope surface with
the bucket cutting edge. In either method,
the surface is roughly finished by operating
the arm lever quickly, keeping the engine
speed at the full throttle, and finely
finished, keeping the engine speed at half
the full throttle. If still finer precision of
finishing is required, a superfine operation
technique of the controls is employed,
while the engine speed is kept at 50% to
70% of the full throttle.

 After roughly finishing the surface,
put the bucket bottom to the foot of a
slope, and lift the bucket through fine
control of the arm pullback and boom
lift. At that time, the bucket angle
changes as the arm is pulled back, so
control the operation of the arm and
the boom for fine finishing.

 When the arm is further pulled back
from a position where it is
perpendicular to the boom or the
slope, a complex operation of the arm +
boom RAISE changes to the one of the
arm + boom LOWER. Thus continuous
leveling is terminated. In such a case,
either reduce the arm speed drastically,
or stop the arm temporarily and try to
pull back the arm and to lower the
boom once again. Then the leveling
work should be done easily.

 For finishing a slope of the natural
ground, use the bucket cutting edge that
is operated by pulling back the arm and
through a fine control of boom RAISE.
The maximum area of a slope surface
covered by this method is up to a level
where the arm is perpendicular to the
surface. For finishing the rest, back up the
loading machine to an appropriate point.

 For finishing the upper part of a slope,
match the bucket bottom with the slope
surface closely, and scrape off the surface
with the bucket cutting edge by pulling
back the arm and lowering the boom,
while keeping the bucket angle constant
(0°). If the bucket angle is too sharp, the
bucket teeth dig in too deeply, so timely
and proper adjustment of this angle is an
important point in this method. In the case
the adjustment is not well timed, stop the
arm and boom once, and start again after
adjustment. The adjustment can be done
easily that way.

The work of loading earth on a dump truck
consists of the following four processes, i.e.
excavation → lifting the boom and
machine’s swing → dumping earth →
lowering boom and swing. There are two
ways of loading earth from an excavator to
a dump truck. One is called a backhoe
loading method, that is, to park the
hydraulic excavator on a higher spot of the
ground than the dump truck and load.

The other is called a swing and load
method, that is, both the hydraulic
excavator and the dump truck are on the
same level of the ground, and the former
swings and loads on the latter. As a loading
method, the former excels in loading
efficiency, visibility and ease of loading.

Determine arm angle θ, too, when
determining other relative spots. It should
allow the bucket to dump earth at the
innermost spot of the truck body, and the
operator of the
loading machine must acquire the feel of
an exact but imaginary point for the
innermost loading beforehand.
Setting bench height and dump truck
height

 Set a bench (landing) for an
excavator as high as the dump truck
body or bit higher than that. Level
off the bench surface to assure the
machine stability.
 After scooping earth, the excavator
swings and waits for the dump
truck, holding the bucket slightly
higher than the dump truck body.
The dump truck backs up with the
location of the bucket in sight. When
the dump truck rear reaches the
loading spot, the operator of the
hydraulic excavator honks a horn to
stop the dump truck.

 In excavating and scooping soft earth of an embankment, dig the bucket in and scoop
the earth at a stroke, keeping bucket angle θ at 60°. This practice is carried out in two
layers of the earth that is to be excavated alternately. Start excavation with the upper
layer, followed by the lower layer, and the earth is loaded on a dump truck. This is an
effective loading pattern with the least resistance in excavation.
(Soft embankment) (Natural ground)
1. Excavating and scooping

 When swinging the upper structure
of a hydraulic excavator, the swing
angle is usually between 30° to 90°.
Make a swing with the engine
running at the full throttle, and make
a complex operation of extending the
arm and lifting the boom, if so
required. (Do not lift the boom any
higher than necessary.) When the
loading machine gets close to the
dump truck, slow down the swinging
speed gradually and stop it without
spilling the earth from the bucket.
A left swing assures the better visibility and ease of loading.
2. Swing with boom raised

3. Dumping earth
 Dump the earth, beginning on the
front most part of the truck body, by
extending the arm.

4. Swing with boom lowered
 3 simultaneous complex operation of
swing + lowering boom + bucket
enables the loading machine to
quickly return to the excavation
point. (Adding extension of the arm
to the above, 4 simultaneous complex
operation is employed to allow the
arm to reach the excavation point.)

 This method is commonly used at a
worksite where there are several
restrictive conditions and hence high
working efficiency cannot be hoped.
The bucket lift amount when the
upper structure swings matches with
the height of the dump truck body at a
swing of 90°. A left swing assures a
better visibility and easiness of
loading. Loading may well be started
with the front most part as shown in
an illustration at left. Better visibility
and easiness of loading are available.

1. Positioning dump truck
 After scooping earth, swing the
loading machine and let it stand by. In
the meantime, the dump truck backs
up, keeping the loading machine in
sight. When the dump truck reaches a
loading point from where the arm can
reach the innermost part of the truck,
honk a horn to stop it. The dump truck
must back up at the direct angle to the
loading machine.

Do not set the arm at its max. reach but leave some allowance so that the bucket
may dump earth at the innermost part of the truck body.
1. Positioning dump truck

2. Excavating and scooping
Start excavation with the arm extended to its max. reach. (This is to minimize the 3
simultaneous complex operation including the arm control when the upper structure
swings.) Hold the bucket at an optimum excavation angle, and scooping can be carried
out without a hitch.

3. Swing with boom lifted
 Start bucket tilting operation as
soon as it passes over a sideboard
of the truck body so that earth may
be dumped in the center. In the
final dumping, make a swing
through swing + boom operation,
and dump the earth while leveling
off the surface of the loaded earth
through complex operation of
extending arm and bucket.

3. Swing with boom lifted
 Approach the dump truck while
operating swing + lifting boom. The
1st and 2nd bucketful's are to be
dumped at the rearmost part of the
truck body, so determine the proper
spot while extending the arm
midway. When getting close to the
truck body, start swinging and
reduce the boom lifting speed
gradually. (It has to be smooth
reduction of speed to prevent the
earth in the bucket from spilling.)

4. Lower boom and swing
 Return to the excavation
point using the 3
simultaneous complex
operation of swing +
lowering boom + bucket. (To
allow the arm to timely reach
the excavation upon arrival,
extend the arm through the 4
simultaneous complex
operation.)

Basic of construction method using hydraulic excavator

Basic of construction method using hydraulic excavator

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Basic of construction method using hydraulic excavator