service repair manual

1. SERVICE MANUAL
KOBELCO CONSTRUCTION MACHINERY AMERICA, LLC.
245 E NORTH AVENUE
CAROL STREAM, IL 60188 U.S.A.
English
Part Number S5YB0016E01
Printed in U.S.A. • Rac
S5YB0016E01
Issued October 2012
1st Edition
APPLICABLE:
230SRLC-3 . . . . . . . . . . . . . LA07-03001~
Hydraulic Excavator
230SRLC-3
Tier 4

2. SHOP
MANUAL model
INDEX
HYDRAULIC EXCAVATOR
SPECIFICATIONSMAINTENANCESYSTEMDISASSEMBLINGTROUBLESHOOTINGE/GOPT.
1
2
3
4
5
6
7
SPECIFICATIONS SECTION
MAINTENANCE SECTION
SYSTEM SECTION
DISASSEMBLY SECTION
TROUBLESHOOTING
ENGINE SECTION
PROCEDURE OF INSTALLING
OPTIONS SECTION
Book Code No.S5YB0016E01
0-1
230SRLC-3

3. 0-2
GENERAL SAFETY INFORMATION
Do not operate or perform any maintenance on this
machine until all instructions found in the OPERA-
TOR’S MANUAL and this MANUAL have been thor-
oughly read and understood.
Improper operation or maintenance of this machine
may cause accidents and could result in serious in-
jury or death.
Always keep the manual in storage.
If it is missing or damaged, place an order with an
authorized our Distributor for a replacement.
If you have any questions, please consult an autho-
rized our Distributor.
(1) Most accidents, which occur during operation, are
due to neglect of precautionary measures and safe-
ty rules. Sufficient care should be taken to avoid
these accidents. Erroneous operation, lubrication
or maintenance services are very dangerous and
may cause injury or death of personnel. Therefore
all precautionary measures, NOTES, DANGERS,
WARNINGS and CAUTIONS contained in the man-
ual and on the machine should be read and under-
stood by all personnel before starting any work with
or on the machine.
(2) Operation, inspection, and maintenance should be
carefully carried out, and safety must be given the
first priority. Messages of safety are indicated with
marks. The safety information contained in the
manual is intended only to supplement safety
codes, insurance requirements, local laws, rules
and regulations.
(3) Messages of safety appear in the manual and on
the machine : All messages of safety are identified
by either word of "DANGER", "WARNING" and
"CAUTION".
1) DANGER- Indicates an imminently hazardous
situation which, if not avoided, will result in
death or serious injury and is represented as
follows:
2) WARNING- Indicates a potentially hazardous
situation which, if not avoided, could result in
death or serious injury and is represented as
follows:
3) CAUTION- Indicates a potentially hazardous
situation which, if not avoided, may result in mi-
nor or moderate injury. It may also be used to
alert against possible damage to the machine
and its components and is represented as fol-
lows:
(4) It is very difficult to forecast every danger that may
occur during operation. However, safety can be en-
sured by fully understanding proper operating pro-
cedures for this machine according to methods
recommended by Manufacturer.
(5) While operating the machine, be sure to perform
work with great care, so as not to damage the ma-
chine, or allow accidents to occur.
(6) Continue studying the manual until all Safety, Oper-
ation and Maintenance procedures are completely
understood by all persons working with the ma-
chine.

4. 0-3
SAFETY PRECAUTIONS
The proper and safe lubrication and maintenance
for this machine, recommended by Manufacturer,
are outlined in the OPERATOR’S MANUAL for the
machine.
Improper performance of lubrication or mainte-
nance procedures are dangerous and could result
in injury or death. Read and understand the MAN-
UAL before performing any lubrication or mainte-
nance.
The serviceman or mechanic may be unfamiliar with
many of the systems on this machine. This makes it
important to use caution when performing service work.
A knowledge of the system and or components is im-
portant before the removal or disassembly of any com-
ponent.
Because of the size of some of the machine compo-
nents, the serviceman or mechanic should check the
weights noted in this manual. Use proper lifting proce-
dures when removing any components. Weight of com-
ponents table is shown in the section ;
SPECIFICATIONS.
The following is a list of basic precautions that must al-
ways be observed.
(1) Read and understand all Warning plates and decal
on the machine before Operating, Maintaining or
Repairing this machine.
(2) Always wear protective glasses and protective
shoes when working around machines. In particu-
lar, wear protective glasses when using hammers,
punches or drifts on any part of the machine or at-
tachments. Use welders gloves, hood/goggles,
apron and the protective clothing appropriate to the
welding job being performed. Do not wear loose fit-
ting or torn clothing. Remove all rings from fingers,
loose jewelry, confine long hair and loose clothing
before working on this machinery.
(3) Disconnect the battery and hang a "Do Not Oper-
ate" tag in the Operators Compartment. Remove ig-
nition keys.
(4) If possible, make all repairs with the machine
parked on a firm level surface. Block the machine
so it does not roll while working on or under the ma-
chine. Hang a "Do Not Operate" tag in the Opera-
tors Compartment.
(5) Do not work on any machine that is supported only
by lift, jacks or a hoist. Always use blocks or jack
stands, capable of supporting the machine, before
performing any disassembly.
Do not operate this machine unless you have
read and understand the instructions in the OP-
ERATOR’S MANUAL. Improper machine opera-
tion is dangerous and could result in injury or
death.
(6) Relieve all pressure in air, oil or water systems be-
fore any lines, fittings or related items are discon-
nected or removed. Always make sure all raised
components are blocked correctly and be alert for
possible pressure when disconnecting any device
from a system that utilizes pressure.
(7) Lower the bucket, dozer, or other attachments to
the ground before performing any work on the ma-
chine. If this cannot be done, make sure the bucket,
dozer, ripper or other attachment is blocked correct-
ly to prevent it from dropping unexpectedly.
(8) Use steps and grab handles when mounting or dis-
mounting a machine. Clean any mud or debris from
steps, walkways or work platforms before using.
Always face to the machine when using steps, lad-
ders and walkways. When it is not possible to use
the designed access system, provide ladders, scaf-
folds, or work platforms to perform safe repair oper-
ations.
(9) To avoid back injury, use a hoist when lifting com-
ponents which weigh 20kg (45lbs) or more. Make
sure all chains, hooks, slings, etc., are in good con-
dition and are the correct capacity. Be sure hooks
are positioned correctly. Lifting eyes are not to be
side loaded during a lifting operation.
(10)To avoid burns, be alert for hot parts on machines
which have just been stopped and hot fluids in
lines, tubes and compartments.
(11)Be careful when removing cover plates. Gradually
back off the last two capscrews or nuts located at
opposite ends of the cover or device and carefully
pry cover loose to relieve any spring or other pres-
sure, before removing the last two capscrews or
nuts completely.
(12)Be careful when removing filler caps, breathers and
plugs on the machine. Hold a rag over the cap or
plug to prevent being sprayed or splashed by liq-
uids under pressure. The danger is even greater if
the machine has just been stopped because fluids
can be hot.

5. 0-4
(13)Always use the proper tools that are in good condi-
tion and that are suited for the job at hand. Be sure
you understand how to use them before performing
any service work.
(14)Reinstall all fasteners with the same part number.
Do not use a lesser quality fastener if replacements
are necessary.
(15)Repairs which require welding should be per-
formed only with the benefit of the appropriate ref-
erence information and by personnel adequately
trained and knowledgeable in welding procedures.
Determine type of metal being welded and select
correct welding procedure and electrodes, rods or
wire to provide a weld metal strength equivalent at
least to that of the parent metal. Make sure to dis-
connect battery before any welding procedures are
attempted.
(16)Do not damage wiring during removal operations.
Reinstall the wiring so it is not damaged nor will be
damaged in operation of the machine by contacting
sharp corners, or by rubbing against some object or
hot surface. Do not connect wiring to a line contain-
ing fluid.
(17)Be sure all protective devices including guards and
shields are properly installed and functioning cor-
rectly before starting a repair. If a guard or shield
must be removed to perform the repair work, use
extra caution and replace the guard or shield after
repair is completed.
(18)The maintenance and repair work while holding the
bucket raised is dangerous due to the possibility of
a falling attachment. Don’t fail to lower the attach-
ment and place the bucket to the ground before
starting the work.
(19)Loose or damaged fuel, lubricant and hydraulic
lines, tubes and hoses can cause fires. Do not bend
or strike high pressure lines or install ones which
have been bent or damaged. Inspect lines, tubes
and hoses carefully. Do not check for leaks with
your hands. Very small (pinhole) leaks can result in
a high velocity oil stream that will be invisible close
to the hose. This oil can penetrate the skin and
cause personal injury. Use card-board or paper to
locate pinhole leaks.
(20)Tighten connections to the correct torque. Make
sure that all heat shields, clamps and guards are in-
stalled correctly to avoid excessive heat, vibration
or rubbing against other parts during operation.
Shields that protect against oil spray onto hot ex-
haust components in event of a line, tube or seal
failure must be installed correctly.
(21)Do not operate a machine if any rotating part is
damaged or contacts any other part during opera-
tion. Any high speed rotating component that has
been damaged or altered should be checked for
balance before reusing.
(22)Be careful when servicing or separating the tracks
(crawlers). Chips can fly when removing or install-
ing a track (crawlers) pin. Wear safety glasses and
long sleeve protective clothing. Tracks (crawlers)
can unroll very quickly when separated. Keep away
from front and rear of machine. The machine can
move unexpectedly when both tracks (crawlers)
are disengaged from the sprockets. Block the ma-
chine to prevent it from moving.

6. 0-5

7. 0-6
NOTE:
This Manual is prepared as a technical material in
which the information necessary for the maintenance
and repairing services of our hydraulic excavators are
collected, and is categorized into 7 Chapters, Specifica-
tion, Maintenance, System, Disassembly, Trouble-
shooting, Engine, and Installation Procedures for
Optional Attachment.
• The Chapter "Specification" describes the specifi-
cations for entire machine and material, which are
instructive for replacement and repairing of attach-
ments.
• The Chapter "Maintenance" describes the material,
which is helpful for maintenance service and adjust-
ments for entire machine.
• The Chapter "System" describes the operating sys-
tem like hydraulic system, electric system, compo-
nents, and so on.
• The Chapter "Disassembly" describes the removal
and installing of assembly mounted on the upper
structure and undercarriage, and the assembling
and disassembling of the associated hydraulic
equipment.
• The Chapter "Troubleshooting" describes how to
find the fault equipment.
• The Chapter "Engine" describes the engines mak-
ing use of the "Maintenance Manual" provided by
the suppliers.
• The Chapter "Installation Procedures for Optional
Attachment" describes the supplements added on
request as required.
This Manual may be properly revised due to the im-
provement of products, modification of specifications,
etc. And there are cases where the system on actual
machine and a part of the contents of this manual may
differ due to the variations of specification by countries.
For the section in which the description is hardly under-
stood, contact our distributor.
The number is assigned to every part handled in this
Manual on account of the description, but the parts,
which cannot be supplied as service parts are con-
tained. Therefore, the order must be placed with re-
spective formal number with due confirmation on the
Parts Manual for applicable machine.

8. 32. ATTACHMENTS
32-16
32.2.1.3 DISASSEMBLY
• When disassembling and servicing the cylinder, check the construction and the availability of service parts as
well as necessary tools and jigs on separate Parts Manual.
• The figures in parentheses after part names correspond to those in Fig. "construction of general cylinder"
• The following explanation and quantities are for a general use cylinder which has separated piston and piston
nut.
In case that piston and piston nut are combined, the construction differs from separated type, refer to the
sentence in parenthesis.
32.2.1.3.1 REMOVING ROD COVER AND PISTON ROD
Use mouth pieces so as not to damage the machined surface of the cylinder tube. Do not make use of the outside
piping as a locking means.
Cover the extended piston rod (2) with cloths to prevent it from being accidentally damaged during operation.
(1)
Hold the clevis section of the tube in a vise.
(2)
Pull out piston rod (2) about 200 mm (8in). Because
the piston rod is heavy, finish extending it with air
pressure after the above-mentioned oil draining
operation.
(3)
Loosen and remove socket bolts (12) of the rod cover
in sequence.
(4)
Strike the corner of the rod cover flange by means of a
plastic mallet till rod cover (3) comes off.
200mm
(8")
2
ALLEN WRENCH
Cover here with cloths
Turn counterclockwise
3
2
12

9. 32. ATTACHMENTS
32-17
32
Since the piston rod assy is heavy in this case, lift the tip of the piston rod (2) with a hoist and draw it out. However,
when piston rod (2) has been drawing out to approximately two thirds of its length, lift it in its center to draw it
completely. However, since the plated surface of piston rod (2) is lifted, do not use a wire rope which may score the
surface, but use a strong cloth belt or a rope.
• At this time, the weight of piston rod (2) is loaded
on rod cover (3). Therefore, lift the top end of the
piston rod with a hoist to the extent that only the rod
weight may be held.
Drawing out piston rod assy (2).
(5)
Draw out the piston rod assy from cylinder tube (1).
Method of drawing out the piston rod assy
(6)
Place the removed piston rod on a horaizontal wooden
V-block.
-Cover a V-block with cloths.
Method of placing the piston rod
(7)
Remove slide ring (18) and (19) from piston (15).
Remove slide ring (18) and (19)
KNOCK THIS EDGE
WITH A PLASTIC MALLET.
LIFT HERE.
2
3
1
LIFT HERE.
OIL PAN
PULL STRAIGHT
SIDEWAYS
HORIZONTALLY
1
PISTON ROD ASSY
WOODEN V-BLOCK
(PLACE CLOTHS)
Remove slide ring by
widening the slit toward
the arrow
15
19
18

10. 32. ATTACHMENTS
32-18
32.2.1.3.2 REMOVING PISTON ASSY
-Note that the tightening torque differs with the type, the working pressure and the mounting method of the piston
(15), though the rod diameter remains the same.
-It is also necessary to place a suitable supporting block near the piston (15). In case a V-block is used, put cloths
or something over the rod to prevent it from damage.
Since piston nut (21) is tightened to a high torque, use a hook wrench suitable for the outside diameter of piston nut
(21). Use care so the hook of the wrench is positively fixed in the groove of the piston nut perimeter.
(1)
Fix piston rod (2) by holding its clevis section in a vise.
Fix the piston rod (2) securely as piston nut (21) is
tightened to a high torque.
How to loosen piston nut (21)
(2)
Scrape off the caulked part of setscrew (22) of piston
nut (21) by means of a hand drill and loosen setscrew
(22) and remove ball (23).
Removing setscrew (22) and ball (23)
(3)
Loosen and remove piston nut (21) or [piston (15)].
How to loosen piston nut (21)
WOODEN V-BLOCK
(PLACE CLOTHS)
WOODEN BLOCK
3
2
15
21
DRILL22
21
23
TURN COUNTER
CLOCKWISE.
EYE WRENCH
15
21

11. 32. ATTACHMENTS
32-19
32
In case that piston and piston nut are combined, the shim (20) is not used.
Take care so rod bushing (4) and the lip of packings (6,7,8,9) may not be damaged by thread of the piston rod (2).
(4)
Remove piston (15) by tapping with plastic mallet,
supporting weight of piston (15) with hoist.
Removing piston (15)
(5)
After removing cushion bearing (13) and cushion seal
(14), separate rod cover (3) from piston rod (2). If it is
too hard to slide it, knock the flanged part of rod cover
(3) with a plastic mallet. But when drawing it out, lift rod
cover (3) by hoist and pull it straight horizontally.
Removing rod cover (3)
4 15
LIFT WITH A HOIST.
PULL STRAIGHT.
STRIKE WITH
A PLASTIC MALLET.
NOTE:
DO NOT
DAMAGE
PISTON ROD
SURFACE.
3 4 6 8,7 9 2

12. 32. ATTACHMENTS
32-20
32.2.1.3.3 DISASSEMBLING PISTON ASSY
Cut the seal ring (16) by tapping it with a screwdriver or a chisel. Take care not to strike it too hard, otherwise the
groove may be damaged.
32.2.1.3.4 DISASSEMBLING ROD COVER ASSY
Take care in this operation not to damage the grooves.
(1)
Remove seal ring (16) and back-up ring (17).
Removing seal ring (16) and back-up ring (17)
(1)
Remove O-ring (10) and back-up ring (11).
Remove back-up ring (11) and O-ring (10) in that
order. Remove back-up ring (11) and O-ring (10) by
pulling and stretching them with an spatula like
earpick.
Removing the outer circumferential seal of rod
cover (3)
(2)
Remove buffer ring (6), U-ring (7) and back-up ring (8).
Each seal is fixed in the groove on the bore and
removing in flawless is impossible.
Stab each seal with a gimlet and pull it out of the
groove.
Removing the inner circumferential seal of rod
cover (3)
HAMMER
O-RING
SCREWDRIVER (OR CHISEL)
BACK-UP RING
USE CARE NOT
TO DAMAGE
THE GROOVE.
SEAL
RING17
15
16
SPATULA
10
11
3
GIMLET
8
7
6
3

13. 32. ATTACHMENTS
32-21
32
32.2.1.3.5 REMOVING PIN BUSHING
(3)
Remove wiper ring (9). When taking out wiper ring (9),
fix rod cover (3) in a vise.
Removing wiper ring (9)
(4)
Remove snap ring (5) and bushing (4).
Remove snap ring (5) first, and remove bushing (4).
But the bushing (4) is press fitted in rod cover (3), so
push it out by press with jig as shown in the figure.
See para 32.2.1.9.3 (1) for removing.
Removing rod bushing (4)
(1) Apply driver to wiper ring (25) of cylinder tube (1)
and piston rod (2), and strike it by hammer lightly.
(2) Push out pin bushing (24) press fitted in cylinder
tube (1) and piston rod (2) with press.
Drawing out pin bushing (24)
SCREW-
DRIVER
HAMMER
VISE
WOOD PIECE
WOOD PIECE
3
9
PRESS HERE
CHUCK ASSY TOOL A
BLOCK TOOL C
BUSHING4
PUSH WITH A PRESS.
JIG J
BASE24
2

14. 32. ATTACHMENTS
32-22
32.2.1.4 CLEANING
(1) After disassembly the cylinder, wash all parts with commercial detergent.
(2) Do not use the used oil seal, O-ring, back-up ring, etc. even if they are not damaged after inspection.
(3) After cleaning, dry all parts by compressed air, and put them on the working bench taking care not to damage
them.
Never use benzene(gasoline, thinner, etc.) because it may be damage the rubber, etc.
32.2.1.5 ASSEMBLING PIN BUSHING
Start assembling the following sub assy
-Cylinder tube assy
-Piston assy
-Rod cover assy
32.2.1.5.1 ASSEMBLING PIN BUSHING
-Before press fitting, apply grease on wiper ring and boss hole.
-Before press fitting the pin bushing, align the position of oil hole.
32.2.1.5.2 ASSEMBLING OF PISTON ASSY
(1) Press fit pin bushing (24) in cylinder tube (1) and
piston rod (2) respectively with press.
(2) Press fit wiper ring (25) in the upper and lower
sides of cylinder tube (1) and piston rod (2)
respectively with press.
Press fitting of pin bushing (24)
(1)
The fitting of seal ring (16) requires special tool as
shown in right Fig. Seal ring (16) is pushed in by press,
etc. with pushing in tool as shown in the figure. (The O-
ring of seal ring (16) and back-up ring (17) on one side
should be installed beforehand.)
How to fit seal ring (16)
PUSH WITH A PRESS
OIL HOLE LOCATION
2
24
15
16
17
PRESS HERE METAL (G)
O-RING
SLIDE JIG (F)
PRESS JIG (E)

15. 32. ATTACHMENTS
32-23
32
Heat them, and they may be soften. But never heat them over 100C degrees (212.0F degrees) or more.
-For piston, stop it once tentatively (for 3 to 5 seconds), and then push it in fully.
-After fitting, wind tape around seal ring (16) 2 or 3 times, and remove it immediately before piston (15) is inserted
in cylinder tube (1).
-Fit slide rings (18) (19) at the same time when piston (15) is inserted in cylinder tube (1).
32.2.1.5.3 ASSEMBLING ROD COVER ASSY
The snap ring (5) can not be fitted when the bushing (4) is not press-fitted fully to the stop end.
(2)
Fit back-up ring (17) on the other side. After fitting,
correct it immediately to prevent from expansion of
seal ring (16) with correcting jig (H) as shown in right
Fig.
Installing seal ring (16)
(1)
Press fit bushing (4) in rod cover (3) with bushing
press-fitting jig (A). Then, fit snap ring (5) in the
groove. Apply hydraulic oil on internal surface of rod
cover (3).
1716
CORRECTIONAL
JIG (H)
PRESS HERE
PRESS FITTING JIG (A)
GROOVE FOR
FIXING SNAP RING (5)
Press bushing till bushing
comes in contact with
this face.
PRESS HERE. (STRAIGHT DOWN)
4
3

16. 32. ATTACHMENTS
32-24
(3)
Fit buffer ring (6), back-up ring (8) and U-ring (7) in their grooves in that order. Before setting packings, coat them
with hydraulic oil (or vaseline if not available). If you forget the coating, the packings may be scored. When
attaching seals, deform them in a heart shape as illustrated.
-U-ring (7) is harder than other packing and it would be difficult to deform them in a heart shape. In such a case, put
a U-ring in the groove obliquely by hand as deep as possible and push in the last part with a push bar till it is set
with a click.
-Buffer ring (6) should be fitted taking care of the fitting direction. The reverse fitting may cause deformation,
damage, etc. of the piston due to high pressure generated between the buffer ring and U-ring.
-If U-ring (7) is set upside down, the lip may be damaged. Check that it is positioned correctly.
-Attach back-up ring (11) on the open air side of O-ring (10). (See above Fig.).
(2)
Apply grease to wiper ring (9), and fit wiper ring (9),
directing the lip side toward the groove of retainer tool
(D). And set retainer tool (D) on rod cover (3) and
press fit wiper ring (9) with press.
Press fitting of bushing (4)
Inserting a seal into the inner circumference of rod
cover.
How to fit U-ring (7)
9
PRESS HERE. (STRAIGHT DOWN)
RETAINER TOOL (D)
U-RING GROOVE
INSERT U-RING INTO GROOVE FROM THIS SIDE.
10
11
7
6
8
9
3
PUSH BAR (WOOD OR PLASTIC)
Tube side

17. 32. ATTACHMENTS
32-25
32
32.2.1.5.4 INSERTING ROD COVER ASSY TO PISTON ROD
Inserting rod cover (3) to piston rod assy by the following procedure.
-For the rod the outer diameter of piston installing section is small, insert spacer on the faucet section of rod first,
and attach inserting guide jig.
-Apply hydraulic oil on the inserting guide jig and outer surface of piston rod lightly to make the insertion smooth.
32.2.1.5.5 ASSEMBLING PISTON ASSY ONTO PISTON ROD
(1)
Install cushion on the extraction side, cushion bearing (13) and cushion seal (14) by the following procedure.
(2)
When cushion is installed on the retraction side, fit cushion bearing (13) and cushion seal (14) by the following
procedure.
(1) Fix piston rod assy on working bench.
(2) Install rod cover (3) on piston rod (2) with inserting
guide jig (I) as shown in right Fig. paying attention
for the lip section of U-ring not to be caught on the
stepped section.
Inserting rod cover (3)
1. Put cushion seal (14) on it, directing the slit
machined side toward the piston side.
2. Fit cushion bearing (13) on it directing the flattening
side as shown in right Fig.
Cushion mechanism on extension side
1. Fit cushion bearing before fitting piston nut. The nut
attached obstructs the fitting of cushion bearing.
2. Put cushion seal on it, directing the slit machined
side toward the piston side.
3. Fit cushion bearing on it directing the flattening side
as shown in right Fig.
4. Put stopper in the groove. Push cushion bearing to
stopper fully, and drive snap ring. Use plastic mallet
in order not to damage the rod, cushion bearing.
Cushion mechanism on retraction side
INSERT GUIDE JIG (I)
PUSH
3
2
FLAT SECTION
Direct slit toward
piston side
PISTON
13
14
Direct slit toward
thread side
THREADED PART
PISTON ROD
SNAP RING
CUSHION SEAL
(Slit 1 place)
CUSHION
BEARING
STOPPER
(Divide into 2 portions)

18. 32. ATTACHMENTS
32-26
Cushion seal and cushion bearing should be fitted taking care of the fitting direction. If they are fitted in reverse
directions, the cushion does not effective.
After installing cushion, be sure that the cushion bearing moves up and down, and right and left.
-In case that piston and piston nut are combined, the shim (20) is not used. Apply the eye wrench to hexagonal part
of piston and loosen the piston directly.
-Always correct the threads in piston nut (21) or [piston (15)] before fixing piston nut, using a tapping.
-Insufficient tightening torque causes an inner leak and a damage of thread. And over tightening torque causes a
bulge of cushion bearing and a deformation of piston contacted surface.
-Clean and decrease (with solvent) the parts of piston assembly, and dry it, then tighten this piston assembly.
(3)
Insert shim (20), and tighten piston nut (21) or [piston
(15)] till it gets tight.
Always tighten the piston nut (21) or [piston (15)] of
each piston to specified torque
(Refer to 32.2.1.7.3).
Tightening piston nut (21)
(4)
Put steel ball (23) into hole and tighten setscrew (22).
Tools: Allen wrench: 6 mm
After tightening the setscrew to a specified torque,
caulk the two places of the thread of the piston nut side
to secure the setscrew.
See para 32.2.1.7.3 for torque.
Attaching setscrew (22)
(5)
Attach two slide rings (18) and (19). Take off vinyl tape
wound around the perimeter of piston (15), apply high-
quality grease (or vaseline) to slide ring (18), (19) and
attach the slide rings in a manner that they may be
coiled around the groove. Set the slide rings about 180
degrees apart with each other so that the slits may not
point to the same direction.
Attaching slide ring (18), (19)
EYE WRENCH
21
ANTI-LOOSENING
CAULKING
V-BLOCK
2022
23
21
2
V-BLOCK
2
191822
21

19. 32. ATTACHMENTS
32-27
32
32.2.1.5.6 OVERALL ASSEMBLY
(1) Place a V-block on a work bench (A wooden V-block is preferable.). Place the cylinder tube assy (1) on it and
fix the assy by passing a wooden bar through the clevis pin hole to lock the assy.
(2) Insert the piston rod assy into the cylinder tube assy, while lifting and moving the piston rod assy with a hoist. In
this operation, apply hydraulic oil (or vaseline) to the inner surface of the tube mouth and the circumference of
the piston. Align the center of the piston rod assy with the center of the cylinder tube assy and put it in straight
forward. When inserting, make sure that slide rings (18), (19) on the perimeter of the piston is not out of the
groove.
(3) Tighten socket bolt (12). Match the bolt holes of the rod cover flange to the threaded holes in the cylinder assy,
and screw in socket bolts (12) one by one. Tighten the bolts to a specified torque, taking care so the bolts may
not be tightened unevenly. See para. 32.2.1.7.3 for torque.
Tools: Allen wrench: 14 mm
Take care so as not to damage the rod surface by accidentally slip a wrench. Covering the rod surface with cloth is
recommended to prevent damage to it.
Inserting piston rod assy
Tightening socket bolts (12)
LIFT
STRAIGHT PREVENT TURNING
WITH WOODEN BAR.
1
ALLEN WRENCH
PLACE CLOTH
TURN CLOCKWISE
12

20. 32. ATTACHMENTS
32-28
32.2.1.6 INSPECTION AFTER ASSEMBLY
-Do not raise the hydraulic pressure above the maximum pressure of 37.8MPa (5480psi) for the cylinder of the
machine.
-Grease coated on the O-rings and the seals of the rod cover may come out. Wipe it off and retest the cylinder in
such a case.
(2) Leak test
1. Apply a test pressure to the retracting and extending sides of the cylinder for three minutes independently, and
check that the rod section and the welds have external leaks and permanent deformation. For an internal leak
test, connect the cylinder with a test unit as shown in below Fig.
2. After completing the test, apply a plug to each port and store the cylinder. (Below Fig.)
• For storage, place the cylinder on wooden V-blocks and bring the cylinder to the most retracted condition.
(1) No-load functional test
Place the cylinder level at no load, operate the piston
rod 5 to 6 strokes by the directional valve and make
sure that it operates without failure.
External leak test
Internal leak test
How to store the cylinder
PUMP
HYDRAULIC CYLINDER
DIRECTIONAL VALVE
H R
MEASURE THE
INTERNAL LEAK.
FROM DIRECTIONAL VALVE
CYLINDER ASSY
PLUG PLUG

21. 32. ATTACHMENTS
32-29
32
32.2.1.7 MAINTENANCE STANDARDS
32.2.1.7.1 INSPECTION AFTER DISASSEMBLY
Visually inspect all parts after cleaning to see that excessive wear, crack and other damage that are detrimental to
use are not present.
(1) Inspection Item
(2) Repair method
Check all seals and parts to see that they do not show excessive damage and wear. For correction of scores on the
piston rod, observe the following procedure:
1. Correct very fine longitudinal scratches with an oilstone. Replace the piston rod if the scratch is so deep as may
be caught by your nail.
2. In case of a smooth indention, recondition by removing the sharp area around the indention with an oilstone. If
the score or the indention is excessive, replace or replate the damaged part.
• Always regrind after replating. The thickness of the plating must be maximum 0.1 mm (0.004 in).
• In case plating is removed to the base metal during reconditioning with an oilstone, do not fail to replate the
surface.
Parts Name Inspecting Portion Inspection Item Remedy
Piston rod
1. Neck of rod pin Presence of crack Replace
2. Weld on rod hub Presence of crack Replace
3. Stepped part to which
piston is attached
Presence of crack Replace.
4. Threads Presence of seizure Recondition or replace
5. Bend Measure degree of bend (See
Fig. "Measuring method")
Refer to Table "Example of
measurement"
6. Plated surface Check that:
1) Plating is not worn off to base
metal
2) Rust is not present on
plating.
3) Scratches are not present.
1) Replace or replate
2) Replace or replate
3) Recondition, replate or
replace.
7. Rod Wear of O. D. Recondition, replate or
replace.
8. Bushing at mounting part Wear of I. D. Replace
Cylinder tube
1. Weld on bottom Presence of crack Replace
2. Weld on head Presence of crack Replace
3. Weld on hub Presence of crack Replace.
4. Tube interior Presence of damage Replace if oil leak is seen.
5. Bushing at mounting part Wear on inner surface Replace
Rod cover
1.Bushing 1) Wear on inner surface
2) Flaw on inner surface
1) See para. 32.2.1.7.2
2) Replace if score is deeper
than coating.

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23. 32. ATTACHMENTS
32-30
32.2.1.7.2 LIMIT OF SERVICEABILITY
Serviceability limits represent the limits of wear on the sliding surfaces of the cylinder tube and the rod that have no
such damage as may degrade the sealing effect.
(1) Clearance between piston rod and rod bushing
Replace the bushing if the clearance between the piston rod and the rod bushing exceeds 0.25mm (0.01in).
(2) Bend of piston rod
The allowable bend of the rod is maximum 1mm / 1m (0.04"/3'3"). For measurement, support both ends of the
parallel section of the piston rod with V-blocks, set a dial indicator in the center between the two V-block turn the
piston rod, and read the difference between the maximum and minimum deflection on the dial indicator.
Table shows an example of measurement.
Even if the bend is within the above limit, the cylinder may not operate smoothly because of localized bend.
Beware of it during function test after assembly. Replace the rod if the cylinder makes a squeaking noise or dose
not operate smoothly.
32.2.1.7.3 TIGHTENING TORQUE
32.2.1.7.4 VOLUME OF OIL LEAK
The oil leak rates as mentioned in 1.6 (2) of Inspection after Assembly are as shown in INSPECTION AFTER
ASSEMBLY 32.2.1.6 (2).
Measuring Method
Cylinder Volume of Internal Oil Leak
Boom 1.0 cc (0.06 cu-in) or below / 3 min
Arm 1.0 cc (0.06 cu-in) or below / 3 min
Bucket 1.0 cc (0.06 cu-in) or below / 3 min
Example of Measurement
Distance between
V-blocks
m (ft-in)
Deflection of the dial indicator
in the middle of the rod.
mm (in)
Remedy
1 (3’3") 1 (0.04") Replace
B A C Unit : N.m (lbf.ft)
267 (200)
367 (270)
171 (126)
5460 (4030)
7690 (5670)
5020 (3700)
Boom
Arm
Bucket
56.9 (42)
56.9 (42)
31.5 (23)
Piston nut
or [Piston]
A
Cylinder
Socket bolt Setscrew
B C

24. 32. ATTACHMENTS
32-31
32
32.2.1.8 TROUBLESHOOTING
Table32-4
Trouble Failed Parts Cause Remedy
1. Oil leak through sliding
surface of piston rod. Oil
ring is formed on piston
rod, and the ring grows up
to oil drops, and they drip.
1. Back-up ring 1. Foreign matter is trapped in the
bore of back-up ring
1. Remove foreign matter.
2. Lips on outer and inner diameter
surfaces of back-up ring are
scored.
2. Replace back-up ring.
3. Other back-up ring are failed. 3. Replace back-up ring
2. U-ring 1. Foreign matter is trapped in the
bore of ring.
1.Remove foreign matter.
2. Score is present on the bore of ring. 2. Replace U-ring.
3. Other rings are failed. 3. Replace U-ring.
3. Buffer ring 1. Foreign matter is trapped in the
bore of ring.
1.Remove foreign matter.
2. Score is present on the bore of ring. 2. Replace buffer ring.
3. Other rings are failed. 3. Replace buffer ring.
4. Wiper ring 1. Foreign matter is trapped in the
bore of wiper ring.
1.Remove foreign matter.
2. Lip on the bore of wiper ring is
scored.
2. Replace wiper ring.
3. Another wiper ring is failed. 3. Replace wiper ring.
5. Piston rod 1. Score is present on the sliding
surface of piston rod.
1.Smooth out the sliding surface with
an oilstone. If leakage occurs even
if the sliding surface is finished
below 1.6S, rod packings may be
scored. Disassemble and inspect it
and replace rod packings as
required.
If leak will not stop by that
treatment, replace piston rod.
2. Hard chromium plating has peeled
off
2. Replate.
2. Oil leaks from the
circumference of rod cover.
1. O-ring 1. O-ring is damaged. 1. Replace O-ring.
2. Backup ring 1. Back-up ring is damaged. 1. Replace back-up ring.
3. Cylinder tube 1. Swelling of cylinder tube. 1. Replace cylinder tube.
3. Oil leaks from welds. 1. Cylinder tube 1. Welds of cylinder are broken. 1. Replace cylinder tube.
4. Cylinder falls by it-self.
[When the rod is loaded with
a static load equal to the
maximum working pressure
multiplied by the area of the
cylinder bore, the maximum
movement of the piston is
more than 0.5mm (0.02") in
ten minutes.]
1. Piston seal 1. Foreign matter is trapped in the
sliding surface of seal ring.
1. Remove foreign matter
2. Score is present on the sliding
surface of seal ring.
2. Replace seal ring..
2. Slide ring
1. Sliding surface of slide rings is
scored.
1. Replace slide ring.
3. Piston rod 1. Elongation.Piston rod and piston
are elongated. (Loose nut)
1. Replace piston rod.
OIL LEAKS FROM HERE
OIL LEAKS FROM HERE
WELDS

25. 32. ATTACHMENTS
32-32
32.2.1.9 JIGS LIST
32.2.1.9.1 SPECIAL JIG LIST (POSSIBLE TO SUPPLY)
When assembling, the following jigs are required.
For above jigs, contact our dealer.
(The Jig No. List provided by cylinder maker is shown in the following page.)
Table32-5
Application Shape
Described
paragraph
For removing and press
fitting bushing
32.2.1.3.4,
32.2.1.5.2
For press fitting wiper
ring
32.2.1.5.2
For correcting seal ring 32.2.1.5.2
For inserting rod cover 32.2.1.5.4
EDGE OF
CHUCK
A D
C
D
INSERTING JIG CORRECTING JIG
E
F
H
G
I