Content .. 38 39 40 41 ..

Takeuchi compact excavator TB125, TB135, TB145 / diesel TNE / diesel Yanmar. Service Manual - page 40

V-39

TROUBLESHOOTING

ARM

TB125, 135, 145

5. Inspect the arm cylinder.

a. Fully retract the bucket cylinder, fully retract

the arm cylinder and lower the bucket to the
ground.

b. Disconnect the two hoses connected to the

cylinder. Insert plugs (1) in the disconnected
hoses and the cylinder piping.

c. Raise the boom and raise the hoe attachment so

it floats above the ground. If the arm dorps, the
cylinder is faulty. If the arm does not drop,
there is leakage inside the control valve.

V-40

TROUBLESHOOTING

ARM

TB125, 135, 145

Is the amount of natural
drop within the standard?

Within the standard.

Normal

Inspect the arm cylinder.

Repair or replace the arm cyl-
inder.

Replace the housing block.

Not within the standard.

Normal

Faulty

There is leakage inside
the control valve.

THE AMOUNT OF ARM NATURAL DROP IS GREAT.

1. Is the amount of natural drop within the

standard?

“II. Specifications, Standards for Judging
Performance”

2. Inspect the arm cylinder.

“V-39”

V-41

TROUBLESHOOTING

BUCKET

TB125, 135, 145

THE BUCKET CYLINDER DOESN’T MOVE, OR THERE IS NO POWER.

Inspect the operation of
actuators other than the
bucket cylinder.

Inspect the operation of
the spool.

Perform a port relief
valve switching test.

Repair or replace the pilot
valve.

Repair or replace the housing
block.

Repair or replace the port re-
lief valve.

Normal

Inspect the pilot valve.

Normal

Does not change.

Faulty

Operation
became normal.

Repair or replace the bucket
cylinder.

Inspect the bucket cylin-
der.

Faulty

The port relief valve is
faulty.

Right Travel

Relief Valve R1

Pump P1

Lever Operated

Places inspected

1. Inspect the operation of actuators other than

the bucket cylinder.

Inspect if the operation of the bucket only is faulty
by the table at right. If operation is faulty, inspect
the main relief valve and the hydraulic pump.

“V-6”

2. Inspect the pilot valve.

“V-29”

3. Inspect the operation of the spool.

“V-37”

V-42

TROUBLESHOOTING

BUCKET

TB125, 135, 145

4. Perform a port relief valve switching test.

When only “bucket load” side is inoperable:
Replace the port relief valve with that of the
normal boom, and test. If the bucket cylinder
operates, the replaced old port relief valve was
faulty.

5. Inspect the bucket cylinder.

At the boom foot, exchange the arm hose with the
bucket hose that is connected to the pipe.
• Move the lever (arm) and check whether the

bucket cylinder operates.

• If the bucket cylinder does not operate, the

bucket cylinder is faulty.

This inspection should be done with the
bucket cylinder fully extended and the arm
cylinder fully retracted. Also, the bucket must
be lowered to the ground.

ARM BUCKET BUCKET ARM

V-43

TROUBLESHOOTING

BUCKET

TB125, 135, 145

THE AMOUNT OF BUCKET NATURAL DROP IS GREAT.

Is the amount of natural
drop within the standard?

Within the standard.

Normal

Inspect the bucket cylin-
der.

Repair or replace the bucket
cylinder.

Replace the housing block.

Not within the standard.

Normal

Faulty

There is leakage inside
the control valve.

1. Is the amount of natural drop within the

standard?

“II, Specifications, Standards for Judging
Performance”

2. Inspect the bucket cylinder.

a. Fully extend the bucket cylinder, fully retract

the arm cylinder and lower the bucket to the
ground,

b. Disconnect the 2 hoses connected to the cylin-

der.
Insert the plugs (1) in the disconnected hoses
and the piping.

c. Raise the boom and raise the hoe attachment so

that it floats above the ground, If the bucket
drops, the cylinder is faulty, If the bucket does
not drop, there is leakage inside the control
valve.

V-44

TROUBLESHOOTING

BOOM SWING

TB125, 135, 145

THE SWING CYLINDER DOESN’T MOVE.

Inspect the operation of
actuators other than the
swing cylinder.

Inspect the operation of
the spool.

Inspect the anti-cavita-
tion valve.

Inspect the swing cylin-
der.

Repair or replace the anti-cavi-
tation valve.

Repair or replace the swing
cylinder.

Normal

Inspect the linkage.

Normal

Faulty

Repair or replace the housing
block.

Normal

Faulty

Adjust, repair or replace the
parts.

1. Inspect the operation of actuators other than

the swing cylinder.

Inspect if the operation of the boom swing only is
faulty by the table at right. If operation is faulty,
inspect the main relief valve and the hydraulic
pump.

“V-6”

2. Inspect the operation of the spool.

“V-10”

3. Inspect the linkage.

“V-11”

4. Inspect the anti-cavitation valve.

If right swing cannot be done, then foreign matter
is caught in the anti-cavitation valve or the valve
is sticking.

5. Inspect the swing cylinder.

Disconnect the hose between the swing cylinder
and the control valve at the control valve side,
then measure the pressure supplied from the valve.
If the supply pressure is normal, the cylinder is
faulty.
• Supply Pressure: 20.6 MPa (210 kgf/cm

)

Left Travel

Relief Valve R2

Pump P2

Lever Operated

Places inspected

V-45

TROUBLESHOOTING

DOZER BLADE

TB125, 135, 145

THE DOZER BLADE CYLINDER DOESN’T MOVE, OR THERE IS NO POWER.

Inspect the operation of
actuators other than the
dozer blade cylinder.

Inspect the operation of
the spool.

Inspect the control valve
supply pressure.

Inspect the swivel joint.

Repair or replace the housing
block.

Repair or replace the swivel
joint.

Normal

Inspect the linkage.

Normal

Faulty

Repair or replace the housing
block.

Normal

Faulty

Adjust, repair or replace the
parts.

Normal

Faulty

The dozer blade cylinder is
faulty.

Repair or replace the dozer
blade cylinder.

1. Inspect the operation of actuators other than

the dozer blade cylinder.

Inspect if the operation of the dozer blade only is
faulty by the table at right. If operation is faulty,
inspect the main relief valve and the hydraulic
pump.

“V-6”

2. Inspect the operation of the spool.

“V-10”

3. Inspect the linkage.

“V-11”

Slew

Relief Valve R3

Pump P3

Lever Operated

Places inspected

Faulty

V-46

TROUBLESHOOTING

DOZER BLADE

TB125, 135, 145

4. Inspect the control valve supply pressure.

Disconnect one of the hoses connected to the
dozer blade section of the control valve. Set a
pressure gauge in its section, operate the dozer
blade operation lever and inspect the supply pres-
sure.
If the pressure indicated is not the value below,
the housing block is faulty.
• Supply Pressure: 19.6 MPa (200 kgf/cm

)

When “dozer blade lower” side does not
operate properly:

• Replace the port relief valve with a new one

having a normal arm, and test. If the dozer
blade cylinder operates, the port relief valve on
the dozer blade side is faulty.

5. Inspect the swivel joint.

Disconnect the hose between the swivel joint and
the dozer blade cylinder on the cylinder side.
Connect a pressure gauge to the disconnected
hose and operate the lever (blade).
• If the measured pressure is not the following

value, the swivel joint is faulty.
Supply pressure: 19.6 MPa (200 kgf/cm

)

V-47

TROUBLESHOOTING

DOZER BLADE

TB125, 135, 145

Is the amount of natural
drop within the standard?

Normal

Inspect for internal leak-
age in the blade cylinder.

Repair or replace the housing
block.

Not within the standard.

Normal

Inspect the swivel joint
and control valve.

THE AMOUNT OF DOZER BLADE NATURAL DROP IS GREAT OR THE DOZER BLADE WON’T
HOLD THE MACHINE UP.

Repair or replace the swivel
joint, or replace the control
valve.

1. Is the dozer blade’s natural drop within the

standard?

“II. Specifications, Standards for Judging
Performance”

2. Inspect for internal leakage in the dozer

blade cylinder.

a. Using the hoe attachment, raise the machine’s

body, then lower the dozer blade fully.

b. Disconnect the dozer blade cylinder’s rod side

hose and drain out the oil in the piping.
Insert a plug (1) in the disconnected hose.

Within the standard.

Faulty

V-48

TROUBLESHOOTING

DOZER BLADE

TB125, 135, 145

c. Raise the boom and apply a load on the dozer

blade.

• If the machine’s body drops while oil drains

out of the cylinder’s piping, the cylinder is
faulty.
If the body drops even though no oil drains out,
the control valve or the swivel joint is faulty.

If the machine cannot be supported by the
dozer blade, try replacing the port relief valve
with a normal one.
If the dozer blade can support the machine’s
body after this, then the port relief valve is
faulty.

3. Inspect the swivel joint and control valve.

Disconnect the hose between the swivel joint and
control valve at the control valve side, then insert
a plug in the disconnected hose.
Apply a load to the dozer blade by the procedure
in the previous item 2, a~c.
If the machine’s body drops, the swivel joint is
faulty.
If the machine’s body does not drop, there is
internal leakage in the control valve.

V-49

TROUBLESHOOTING

AUXILIARY HYDRAULICS

TB125, 135, 145

THE PROPORTIONAL CONTROL IS IMPOSSIBLE (TB145).

Inspect the operation of
actuators other than the
auxiliary line.

Inspect the proportional
controller.

Inspect movement of the
spool.

Repair or replace the control
valve.

Normal

Inspect the proportional
control solenoid valve.

Faulty

Repair or replace.

Repair or replace the propor-
tional control solenoid valve.

Faulty

1. Inspect the operation of actuators other than

the auxiliary line.

Check the table at right to see if the problem lies
with the auxiliary line alone. If the problem does
lie with the auxiliary line, then check the main
relief valve and the hydraulic pump (P2).

“V-6”

2. Inspect the proportional controller.

“III-115~117”

Lever operated

Left Travel

Relief valve R2

Pump P2

Places to be checked

V-50

TROUBLESHOOTING

AUXILIARY HYDRAULICS

TB125, 135, 145

3. Inspect the proportional control solenoid

valve.

a. Disconnect the hose running from the propor-

tional control solenoid valve to the control
valve (auxiliary section) at the control valve.

b. Fit a pressure gauge to the hose.
c. Operate the proportional control lever on the

left pilot valve to position it at various angles.
If the pressure level falls between 0 and 3.4
MPa for each angle, it is normal.

“IV. Hydraulic Units, Proportional Con-
trol Solenoid Valve”

4. Inspect movement of the spool.

“IV. Hydraulic Units, Control Valve”

V-51

TROUBLESHOOTING

AUXILIARY HYDRAULICS

TB125, 135, 145

THE FLOW IN THE AUXILIARY HYDRAULIC CIRCUIT CANNOT BE CONTROLLED (TB145).

Inspect the supply pres-
sure to the solenoid valve
(auxiliary).

Inspect the fuse.

Inspect the relay.

Inspect the solenoid valve
(auxiliary).

Replace the relay.

Repair or replace the solenoid
valve (auxiliary).

Normal

Inspect the auxiliary hy-
draulics switch.

Normal

Faulty

Replace the fuse.

Normal

Faulty

Replace the auxiliary hydrau-
lics switch.

Normal

Faulty

Inspect the operation of
the spool.

Repair or replace the housing
block.

1. Inspect the supply pressure to the solenoid

valve (auxiliary).

Disconnect the hose between the pilot valve
(travel) and the solenoid valve (auxiliary) on the
solenoid valve (auxiliary) side. Connect a pres-
sure gauge to the disconnected hose and measure
the pilot pressure.
• Keep the plug assembles on the port of the

disconnected solenoid valve.

• Standard value: Approx. 3.4 MPa

Faulty

V-52

TROUBLESHOOTING

AUXILIARY HYDRAULICS

TB125, 135, 145

2. Inspect the fuse.

Operate the solenoid valve and check the fuse for
the power supply circuit.

3. Inspect the auxiliary hydraulics switch.

Press the auxiliary hydraulics switch to turn it
“ON”. While it is this condition, check if there is
continuity with a tester.

4. Inspect the relay.

Press the auxiliary hydraulics switch to turn the
relay to “ON”. Check whether the voltage is
applied to the solenoid valve by using a tester. Be
sure to stop the engine before starting the inspec-
tion.

5. Inspect the solenoid valve (auxiliary).

a. Turn the start switch “ON”.
b. Press the protruding portion of the solenoid

valve lightly.

c. Turn the auxiliary hydraulics switch “ON”.
d. If the spool moves and vibration can be felt

with the fingertip when the circuit changes,
then it is normal.

6. Inspect the operation of the spool.

“V-43”

L3E025E

BLACK

RED

GRAY

BLUE

L3E026

L3E027

V-53

TB125, 135, 145

VI .

ENGINE

Machine Serial No.

12510003~12514525

12514526~

13510004~13514050

13514051~

14510004~14513260

14513261~

Mounted Engine

3TNE82A

3TNV82A

∗

3TNE88

3TNV88

∗

4TNE88

4TNV88

∗

Machine Model

TB125

∗

Fuel Injection Equipment Model YPD-MP2/YPD-MP4

TB135

TB145

Content .. 38 39 40 41 ..