PDF Service Manual Komatsu PC128UU-2 Excavator - 5 MB
This service and repair manual is specifically for the Komatsu PC128UU-2 excavator, serial numbers 5001 and up.
The PC128UU-2 is known for its performance in confined spaces, and this guide provides all the necessary information to keep it running flawlessly.
Inside, you will find detailed procedures for troubleshooting, disassembly, repair, and reassembly.
It's the same manual used by Komatsu technicians, offering reliable and accurate instructions for any maintenance task.
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--- Page 1 ---
SEBM018506
MACHINE MODEL SERIAL NUMBER
PC128UU-2 5001 and up
• This shop manual may contain attachments and optional equipment that are not available
in your area. Please consult your local Komatsu distributor for those items you may re-
quire.
Materials and specifications are subject to change without notice.
• PC128UU-2 mounts the S4D102E-1 engine.
For details of the engine, see the 102 Series Engine Shop Manual.
© 2003 1
All Rights Reserved
Printed in Japan 07-03(02) 00-1
(6)
--- Page 3 ---
FOREWORD METHOD OF DISASSEMBLING, CONNECTING PUSH-PULL TYPE COUPLER
METHOD OF DISASSEMBLING, CONNECTING PUSH-PULL TYPE COUPLER
¤ Before carrying out the following work, release
the residual pressure from the hydraulic tank.
Type 1
For details, see TESTING AND ADJUSTING,
Releasing residual pressure from hydraulic
¤
tank.
Even if the residual pressure is released from
the hydraulic tank, some hydraulic oil flows out
when the hose is disconnected. Accordingly,
prepare an oil receiving container.
Disconnection
1) Release the residual pressure from the hydrau-
lic tan k. Fo r d e tails , se e TES TIN G AN D
ADJUSTING, Releasing residual pressure from
hydraulic tank.
2) Hold adapter (1) and push hose joint (2) into
mating adapter (3). (See Fig. 1)
★ The adapter can be pushed in about 3.5
mm.
★ Do not hold rubber cap portion (4).
3) After hose joint (2) is pushed into adapter (3),
press rubber cap portion (4) against (3) until it
clicks. (See Fig. 2)
4) Hold hose adapter (1) or hose (5) and pull it out.
(See Fig. 3)
★ Since some hydraulic oil flows out, prepare
an oil receiving container.
Connection
1) Hold hose adapter (1) or hose (5) and insert it in
mating adapter (3), aligning them with each
other. (See Fig. 4)
★ Do not hold rubber cap portion (4).
2) After inserting the hose in the mating adapter
perfectly, pull it back to check its connecting
condition. (See Fig. 5)
★ When the hose is pulled back, the rubber
cap portion moves toward the hose about
3.5 mm. This does not indicate abnormality,
however.
00-8
--- Page 4 ---
FOREWORD CONVERSION TABLE
Liter to U.S. Gallon
1l = 0.2642 U.S. Gal
0 1 2 3 4 5 6 7 8 9
0 0 0.264 0.528 0.793 1.057 1.321 1.585 1.849 2.113 2.378
10 2.642 2.906 3.170 3.434 3.698 3.963 4.227 4.491 4.755 5.019
20 5.283 5.548 5.812 6.076 6.340 6.604 6.869 7.133 7.397 7.661
30 7.925 8.189 8.454 8.718 8.982 9.246 9.510 9.774 10.039 10.303
40 10.567 10.831 11.095 11.359 11.624 11.888 12.152 12.416 12.680 12.944
50 13.209 13.473 13.737 14.001 14.265 14.529 14.795 15.058 15.322 15.586
60 15.850 16.115 16.379 16.643 16.907 17.171 17.435 17.700 17.964 18.228
70 18.492 18.756 19.020 19.285 19.549 19.813 20.077 20.341 20.605 20.870
80 21.134 21.398 21.662 21.926 22.190 22.455 22.719 22.983 23.247 23.511
90 23.775 24.040 24.304 24.568 24.832 25.096 25.361 25.625 25.889 26.153
Liter to U.K. Gallon
1l = 0.21997 U.K. Gal
0 1 2 3 4 5 6 7 8 9
0 0 0.220 0.440 0.660 0.880 1.100 1.320 1.540 1.760 1.980
10 2.200 2.420 2.640 2.860 3.080 3.300 3.520 3.740 3.950 4.179
20 4.399 4.619 4.839 5.059 5.279 5.499 5.719 5.939 6.159 6.379
30 6.599 6.819 7.039 7.259 7.479 7.969 7.919 8.139 8.359 8.579
40 8.799 9.019 9.239 9.459 9.679 9.899 10.119 10.339 10.559 10.778
50 10.998 11.281 11.438 11.658 11.878 12.098 12.318 12.528 12.758 12.978
60 13.198 13.418 13.638 13.858 14.078 14.298 14.518 14.738 14.958 15.178
70 15.398 15.618 15.838 16.058 16.278 16.498 16.718 16.938 17.158 17.378
80 17.598 17.818 18.037 18.257 18.477 18.697 18.917 19.137 19.357 19.577
90 19.797 20.017 20.237 20.457 20.677 20.897 21.117 21.337 21.557 21.777
00-18
--- Page 5 ---
GENERAL SPECIFICATIONS
Machine model PC128UU-2
Serial No. 5001 and up
Type Reciprocating piston
cylinder (inside diameter) mm 105
Diameter of pistonrod mm 70
Stroke mm 1,055
Max. distance between pins mm 2,555
Min. distance between pins mm 1,500
fype Reciprocating piston
Cylinder (inside diameter) mm 115
Diameter of pistonrod mm 75
Stroke mm 272.5
Max. distance between pins mm 1,230.5
Min. distance between pins mm 958
Type Reciprocating piston
Cylinder (inside diameter) mm 90
Diameter of pistonrod mm 60
Stroke mm 885
Max. distance between pins mm 2,263
Min. distance between pins mm 1,378
Type Reciprocating piston
Cylinder (inside diameter) mm 130
Diameter of pistonrod mm 70
Stroke mm 346
Max. distance between pins mm 1,818
iin. distance between pins mm 1,472
Type Reciprocating piston
Cylinder (inside diameter) mm 115
Diameter of pistonrod mm 75
Stroke mm 181
Max. distance between pins mm 870
Min. distance between pins mm 689
01-6 PC128UU-2
--- Page 6 ---
STRUCTURE AND FUNCTION SWING CIRCLE
SWING CIRCLE
-
-
-
-
-
5
4
3
A-A
B-B c-c
l--A
‘I
9JA01330
1. Greasing to swing circle bearing Specification
2. Greasing to swing circle pinion Reduction ratio : 90/l 1 = 8.182
4. Seal Grease : G2-LI
5. Ball Amount of filled grease : 9.1 f?
6. Inner race
a. Inner race soft zone position
b. Outer race soft zone position
1 O-6 PC1 28UU-2
--- Page 7 ---
STRUCTURE AND FUNCTION HYDRAULIC PUMP
Function
l This pump converts engine rotation and
torque transmitted to the pump shaft into
hydraulic energy and’discharges pressurized
oil according to load.
l This pump can change delivery when the
swash plate angle is changed.
IO
A-A 9JUOOO77
Structure
l The cylinder block (7) is supported to the shaft
(1) with the spline a, and the shaft (1) is sup-
ported with the front and rear bearings.
l The shoe (5) is punched to the tip of the pis-
ton (6) with a concave ball so that the piston
(6) and the shoe (5) form a spherical bearing.
l The shoe (5) is always pressed to the plane A
of the rocker cam (4) and slides in a circle.
The rocker cam (4) leads highly pressurized
oil together with the cylindrical plane B with
the cradle (2) fixed to the case, forms a static
pressure bearing and slides.
l The piston (6) moves in the axial direction rela-
tively in each cylinder of the cylinder block
(7).
l The cylinder block (7) rotates relatively while
sealing pressurized oil against the valve plate
(8), and the plane is designed to balance the
oil pressure properly.
l Oil in each cylinder of the cylinder block (7) is
absorbed and discharged through the valve
plate (8).
JO-16 PC1 28UU-2
--- Page 8 ---
STRUCTURE AND FUNCTION HYDRAULIC PUMP
in
ve
PEN
-0
ii
SVPO7607
4) When the servo piston balances
l Suppose that the area receiving pressure At the time, the relations of the areas re-
on the piston large diameter side is Al, ceiving pressure at the both ends of the
the area on the piston small diameter side servo piston are A0 : Al = 1 : 1.75. When
is A0 and the pressure applied to the pis- they balance with each other, the pres-
ton large diameter side is PEN. sures applied to the both ends of the pis-
l When the pump discharge pressure PP of ton are related as follows: PP : PEN + 1.75
the LS valve balances with the combined : 1.
force of the LS pressure PLS and the The spring (4) force has been adjusted so
spring (4) force 2 and the relations A0 x that the spool (6) balance stop position is
PP = Al x PEN hold, the servo piston (12) determined at the center of the standard
will stop at the position and the swash when PP-PLS = 2.21 MPa (22.5kg/cm2).
plate angle will be held at the intermedi-
ate position. (The openings of the D port
to the E port and of the C port to the D
port of the spool (6) stop almost at the
same position.)
1 O-26 PC1 28UU-2
--- Page 9 ---
STRUCTURE AND FUNCTION CONTROL VALVE
8-spool valve (without service valve)
BB
-rJ A7 A8 --Y 88 87
AA
I--
B
+A
A5
k TS2
A3
A2
Al -----l-x--
BB--i
PAl’ :
\
k-B
-D TB
5
0
7
0
9
IO
S
11
12
13
14
I
TSW PBl TC
9JYOO291
PC128UU-2
--- Page 10 ---
STRUCTURE AND FUNCTION SUCTION SAFETY VALVE
SUCTION SAFETY VALVE
(SAFETY VALVE WITH SUCTION FOR SERVICE PORT)
1. Suction valve
2. Main valve
3. Piston
4. Piston spring
5. Poppet
6. Poppet spring
7. Suction valve
8. Sleeve
9. Adjustment screw
IO. Lock nut
’ CT 9JUOO112
Specification
Part No. (Reference) 1 Set pressure 1 Use
24.5 MPa (250 kg/cm?
709-70-74600 For crusher
(at the time of 5fYmin.I
17.2 MPa (175 kg/cm*)
709-70-74700
(at the time of 5e/min.)
1O-46 PC1 28UU-2
--- Page 11 ---
STRUCTURE AND FUNCTION CLSS
2. Travel valve
PP
3 SDP03739
Operation
l When the spool (1) is operated, the pump dis-
charge pressure PP will be led to the actuator
circuit A through the bridge passage b from
the flow control valve (2) and the spool notch
a.
l At the same time, the actuator circuit pres-
sure PA moves the pressure reducing valve
(3) to the right side, and the notches c and d
interconnect to the travel junction circuit e and
the LS circuit PLS respectively.
l So, the actuator circuit pressure PA (= A) is
led from the notch c to the LS circuit PLS
through the notch d.
* The travel circuit is different from the work
equipment circuit, the actuator circuit pres-
sure PA is directly led to the LS circuit PLS.
1 O-56 PC128UU-2
--- Page 12 ---
STRUCTURE AND FUNCTION CLSS
ARM REGENERATION CIRCUIT
1. At arm in and own weight fall
Function
l When the arm falls due to its own weight be-
cause the head pressure A in the arm cylin-
der (1) is higher than the bottom pressure B
during arm digging, this circuit brings the re-
turn flow on the head side to the bottom side
to increase the cylinder speed.
T PLS
9JYOO300
Operation 1. Arm cylinder
l When the arm falls for digging due to its own 2. Arm spool
weight, the head side pressure A in the arm 3. Check valve
cylinder (1) will rise above the bottom side
pressure B. A : Head circuit (pressure)
l At the time, part of the return flow on the head B : Bottom circuit (pressure)
side passes through the regeneration passage PP : Pump circuit (pressure)
a of the arm spool (21, pushes the check valve
(3) to open it and flows to the bottom side.
l This increases the arm digging speed.
1O-66 PC1 28UU-2
--- Page 13 ---
STRUCTURE AND FUNCTION CLSS
3. At simultaneous operation of boom + swing
Function
l When the boom is raised at the time of swing-
ing, the swing pool stroke will be controlled
and the flow to the boom will be distributed
more to raise the boom more.
1) When the boom is not raised
9JYOOO24
Operation 1. Spool (swing)
l Since the SA and SB ports are interconnected 2. Piston
to the drain and no force is given to the pis- 3. Plug
ton (2), the stroke of the spool (1) is not con- 4. Case
trolled. So, the spool (1) comes to the cases 5. Case
(4) and (5) and the stroke increases by STl.
This increases the filtering oil flow. ST1 : Spool stroke
1 O-76 PC128UU-2
--- Page 14 ---
STRUCTURE AND FUNCTION SELF PRESSURE REDUCING VALVE
__-_--__-__
Function M IN3. 66MPa
l The self pressure reducing valves reduces the PI P ort
discharge pressure of the main pump and
supplies it to the solenoid valve, the PPC valve,
I
etc. as the control pressure.
ort
T Port
Hydraulic circuit
SVP07622
1. At engine stop (total low pressure)
SVP07623
Operation
l The spring (6) pushes the poppet (5) t the seat, l The spring (3) pushes the valve (2) to the left
and the circuit between the ports PR and T is side, and the circuit between the ports Pl and
closed. P2 is closed.
l The spring (7) pushes the valve (8) to the left
side, and the circuit between the ports Pl and
PR is open.
1O-86 PC128UU-2
--- Page 15 ---
STRUCTURE AND FUNCTION TRAVEL MOTOR
Operation of brake valve
l The brake valve consists of the check valves
(3a) and (3b), the counterbalancevalve (5) and
the safety valve (6), and the circuit configura-
tion is as per the right figure. 3a
l Functions and operations of these compo-
nents are as follows :
SJP07627
Counterbalance valve, check valve
Function
l When traveling down a slope, the own weight
falling force will make the machine travel
faster than the motor rotation. So, traveling
with reduced engine speed is very dangerous 3a
because the motor idles and runs away.
These valves let the machine travel at a speed
appropriate for the engine speed (pump de-
livery) to prevent this danger.
Operation at oil supply
l When the travel lever is operated, the pres-
surized oil from the control valve will be sup-
plied to the PA port, push and open the check
valve (3a) and flow from the MA port on the
motor inlet side to the MB port on the motor
outlet side.
Since the motor outlet circuit is closed with
the check valve (3b) and the counterbalance
valve (51, however, the supply-side pressure
will rise.
SJP07628
1 O-96 PC1 28UU-2
--- Page 16 ---
STRUCTURE AND FUNCTlON SWING MOTOR
Effect explanation drawing
:With reversal rotation
Prevention valve
_ ,Without reversal rotation
Prevention valve
MA Pressure
MB Pressure
Motor rotat ion
Start Brake
Time t
SJPO7637
10406 PC128UU-2
--- Page 17 ---
STRUCTURE AND FUNCTION PPC VALVE
PPC VALVE
FOR SWING OF WORK EQUIPMENT
9JYOOO39
P : From main pump P3 : Left : Swing right/Right : Bucket for digging
Pl : Left: Arm for dump/Right : Boom down P4: Left : Swing left/Right : Arm for dump
P2 : Left : Arm for digging/Right : Boom up T :Totank
lo-116 PC1 28UU-2
--- Page 18 ---
STRUCTURE AND FUNCTION PPC VALVE
3. In the fine control mode (when the operation
lever is shifted back to its original position)
l As the lever (5) starts returning, the spool (1)
is pushed up by force of the centering spring
(3) and Pl port pressure. By this move, the
fine control hole f is connected to the drain
room D and relieves pressurized oil of PI port
to it.
l If PI port pressure goes excessively low, the
spool (1) is pushed down by the metering
spring (2) and passage between the fine con-
trol hole f and the drain room D is shut down.
And, almost at the same time, the hole is con-
nected to the pump pressure room PP and
starts supplying pump the pressure. This sup-
ply continues until the Pl port pressure is re-
covered to the level equivalent to the lever
position.
l When the operation valve spool returns, oil
in the drain room D flows in through the fine
control hole f’ on the not moving side valve.
Oil is then conducted via P2 port to the room
B to fill it up.
SJP07648
4. In the full stroke mode
l When the disk (5) pushes down the piston (4)
and the retainer (7) pushes down the spool
(l), connection of the fine control hole f is
switched from the drain room D to the pump
pressure room PP.
l Thus, pilot pressurized oil from the control
pump passes through the fine control hole f
and conducted to A room via Pl port to push
the operation valve spool.
l Return oil from B room is conducted from P2
port to the drain room D via the fine control
hole f’.
Control valve
SJP07649
lo-126 PC128UU-2
--- Page 19 ---
STRUCTURE AND FUNCTION ENGINE CONTROL
ONE-TOUCH DECELERATION
Ene ins stop
solenoid valve
(Operation)
qwi (Cableextended)
I(Power SUPPIY) I
deceleration SW itch
deceleration
--
SJP07723
Pressing the one-touch deceleration switch
conducts the deceleration signal to the decel- Engine
eration controller. Speed (r pm)
The deceleration controller turns on the one- -
touch deceleration pilot lamp and, at the same
time, drives the fuel adjust motor to slow
Decelerated Speed
down the engine speed to low idling level. *
. Pressing the one-touch deceleration switch Max. I--
once turns on low idling and pressing it again
restores the speed set on the fuel adjust dial.
* The one-touch deceleration function applied -Time (Sec. 1
to stop the engine is cancelled at the next start. Deceleration Deceleration
Namely, when you resume your operation, the ON OFF SJP07778
engine operation will be driven at the speed
set on the fuel adjust dial.
* As long as the one-touch deceleration mode
is continued, you cannot change the engine
speed from the fuel adjust dial, namely the
engine speed remains at the low idling.
10436 PC1 28UU-2
--- Page 20 ---
STRUCTURE AND FUNCTION ELECTRIC CONTROL SYSTEM
TRAVEL CONTROL FUNCTION
j Travel speed
1selection Travel speed
I solenoid valve selector switch
L. H. R. H.
travel travel
Oi I
(Travel sisnal)
Pressure (Trave I act
.I I
swi rcn -ration sianal)
Controller d
(Power SUPPIY)
L
SJP07732
Function
Travel speed selection
l Travel speed is switched according to changes Travel speed 1 LOW 1 HIGH
in the motor capacity that you can cause from selector switch (low speed) (high speed)
the travel speed selector switch or accelera- Motor capacity
52.7 37.2
tion pedal. (cc/rev)
Travel speed
3.2 4.6
(km/h)
Travel motor angle of
Max. Min.
inclination
lo-146 PC1 28UU-2
--- Page 21 ---
STRUCTURE AND FUNCTION 4-SYSTEM
4. Cancel function
. If the emergency stop function is turned on,
or if the controller or any of the potentiom-
eters fails, the controller will stop action of
every actuator by cutting off signal current to
the solenoid valve and EPC valve.
. This situation requires your immediate check-
ups. In case the machine must be moved to a
safe place before starting the checkups, use
the emergency work equipment operation
switch situated under the operator seat. Turn-
ing this switch on allows you to move the
tmereencv work eaurpmenr operation swi
SJP07739
work equipment to any desired location.
. As soon as the emergency work equipment
operation switch is turned on, the alarm
buzzer will start sounding and the electronic Stop cancel opera- Every actuator
system caution lamp will also start flashing tion
to notify the operator that the cancel function
has been turned on. Alarm buzzer Sounded for 7 seconds
* When you want to swing the work equipment,
turn on the swing/park brake release switch
at the same time. Electronic system Delayed flashing inter-
* If any failure is present in the electric system caution lamp vals (once every second)
of the solenoid valve or EPC valve, this can-
cel function is not available.
When the error code “Failure in Solenoid Sys-
tem” is displayed on the monitor panel depth
indicator, you must not turn on the emergency
work equipment operation switch.
* If you turn on the emergency workequipment
operation switch after removing the control-
ler, boom up/down and arm retract (EPC valve
system) operation won’t be cancelled.
* The emergency work equipment operation
switch is an auto-return type. Namely, if you
move your hand off the switch in the ON po-
sition, it will automatically return to the OFF
position.
1O-l 56 PC128UU-2
--- Page 22 ---
STRUCTURE AND FUNCTION 4-SYSTEM
AUTOMATIC HEIGHT AND DEPTH STOP SYSTEM
The automatic height stop function is capable Monitor Panel
of stopping move of the boom when it reaches
the predetermined height during operation.
The automatic depth stop function is capable
of stopping move of the boom when it reaches
the predetermined depth during operation.
These functions are helpful in ensuring work
\
safety and efficiency when working in job sites Mode selector switch
where obstacles such as piping and electric Depth
wires are present-; Depth
indication
Oset
SJPO7751
Height setup function [height mode]
You can stop move of the boom during op-
eration at any height you have previously set.
You can limit height of the work equipment Specif i
height
by setting limit on the boom lift height.
This function reduces speed of the boom prior
to the forced stop to minimize resulting shocks
or impacts.
Note that this function is not usable for limit-
ing the bucket height.
[Setup procedures]
l Shift the mode select switch to the “Height”.
l Lift the boom up to the height where you want
to set the limit.
l Turn the setup switch to the “SET” position
to make sure that the buzzer is sounded three