Takeuchi Mini Excavator TB215R (No.215000003~). Operator's Manual - page 16

BOOM

5G0AX001

2. Check the pilot valve.

Disconnect the hose connecting the pilot valve and
the control valve (boom block) from the control valve.
Fit the pressure gauge to the hose just disconnected.

• Operate the lever (boom) and measure the pres-

sure.

• If the pressure is between 0 and 3.4 MPa (0 to 493

PSI) depending on the lever angle, the pilot valve
is normal.

3. Check the spool operation.

Disconnect the hose connecting the control valve
(boom block) and the boom cylinder from the cylin-
der. Fit the pressure gauge to the discharge port on
the control valve.

• Operate the lever (boom) and measure the pres-

sure.
Supply pressure: 21.0 MPa (3045 PSI)

4. Test by replacing the port relief valve.

Replace the port relief valve in question with a normal
port relief valve. If the boom cylinder operates with
the replacement valve, the port relief valve used on
the boom side is faulty.
Make sure to return the port relief valve to its regular
position after the above inspection.

5. Check the boom cylinder.

a. Disconnect the hose connecting the control valve

and the boom cylinder from the control valve side.

b. Connect the hose just disconnected to the arm or

bucket block.

c. Try to operate the boom cylinder. If the cylinder

fails to operate, the cylinder is faulty.

Before performing steps “a” through “c” above, fully
extend the bucket cylinder, completely retract the
arm cylinder and lower the bucket to the ground.

5G0AI01Z

TROUBLESHOOTING

BOOM

5G0AX001

Boom cylinder operation is slow or lacks force.

1. Is the speed of the boom cylinder within specs?

“2. Service data, Performance criteria”

2. Check the pilot valve.

“The boom cylinder does not move, 2. Check
the pilot valve”

3. Check the spool operation.

“The boom cylinder does not move, 3. Check
the spool operation”

4. Test by replacing the port relief valve.

“The boom cylinder does not move, 4. Test by
replacing the port relief valve”

Is the speed of the boom
cylinder within specs?

Within specs

Normal

Out-of-specs

Check the pilot valve.

Faulty

Repair or replace the pilot
valve.

Normal

Check the spool opera-
tion.

Faulty

Repair or replace the housing
block.

Normal

Test by replacing the port
relief valve.

Problem solved

The port relief valve is
faulty.

Repair or replace the port re-
lief valve.

No change

Check the boom cylinder.

Faulty

Repair or replace the boom
cylinder.

TROUBLESHOOTING

BOOM

5G0AX001

5. Check the boom cylinder.

Check for leakage inside the boom cylinder (1)
a. With the bucket cylinder fully retracted and the

arm cylinder extended slightly from the fully re-
tracted position, lower the bucket tip to the
ground.

b. Disconnect hose (A) from the rod side only and

drain oil from the piping. Insert a plug (1) into the
disconnected hose.

c. Retract the arm cylinder to lift the bucket off the

ground. If oil leaks from the cylinder piping from
which the hose was disconnected and the boom
cylinder rod retracts, the cylinder is leaking inter-
nally. If no oil leaks from the cylinder piping and
the boom cylinder rod retracts, the control valve is
leaking internally.

Check for leakage inside the boom cylinder (2).
a. Set the machine in the posture shown in the fig-

ure.

TROUBLESHOOTING

BOOM

5G0AX001

b. Disconnect hose (B) from the head side only and

drain oil from the cylinder piping. Insert a plug (2)
into the disconnected hose.

c. Operate the bucket to raise the machine body. If

oil leaks from the cylinder piping from which the
hose was disconnected and the boom cylinder
rod extends, the cylinder is leaking internally.
If no oil leaks from the cylinder piping and the
boom cylinder rod extends, the control valve is
leaking internally.
If the cylinder is damaged internally, the system
will need to be flushed out to remove any debris.

TROUBLESHOOTING

BOOM

5G0AX001

When the control lever is pulled slowly, the boom drops temporarily.

1. Check the load check valve in the control valve.

a. Disconnect the control valve end of the hose con-

necting the control valve and the boom cylinder
together.

b. Connect the disconnected hose to the arm or

bucket block.

c. Operate the boom cylinder.

If the boom cylinder operates normally, it indi-
cates that the load check valve is faulty.

Before performing steps a to c above, set the ma-
chine posture as follows.

• Fully extend the bucket cylinder, fully retract the

arm cylinder, and rest the bucket on the ground.

When the spool first starts to pull, the oil pressure is
low and the flow rate is low. If the load check valve is
faulty, the oil will temporarily flow backward due to
the load applied to the boom cylinder. As a result, the
boom temporarily drops.

2. Check for leakage inside the boom cylinder.

If the oil flows from the head side (A) to the rod side
(B) due to a faulty boom cylinder piston or tube, the
boom temporarily drops because of the low oil pres-
sure and small flow rate when the spool first starts to
pull. Also, the cylinder will have insufficient drive
force. However, the amount of spontaneous drop will
also be large in this case.

• Check the cylinder.

“Boom cylinder is slow or lacks force, 5. Check
for boom cylinder.”

Check the load check
valve in the control valve.

Faulty

Repair or replace the housing
block.

Normal

Check for leakage inside
the boom cylinder.

Faulty

Repair or replace the boom
cylinder.

TROUBLESHOOTING

BOOM

5G0AX001

Spontaneous drop of the boom cylinder is too large.

1. Is the spontaneous drop of the boom cylinder within

specs?

“2. Service data, Performance criteria”

2. Check for leak inside the boom cylinder.

“Boom cylinder operation is slow or lacks force,
5. Check the boom cylinder”

3. Test by replacing the port relief valve.

“The boom cylinder does not move, 4. Test by
replacing the port relief valve”

Is the spontaneous drop
of the boom cylinder with-
in specs?

Within specs

Normal

Out-of-specs

Check for leak inside the
boom cylinder.

Faulty

Repair or replace the boom
cylinder.

Normal

Test by replacing the port
relief valve.

Problem solved

The port relief valve is
faulty.

Repair or replace the port re-
lief valve.

No change

Oil leak inside the control
valve.

Faulty

Replace the housing block.

arm

TroubleshooTing

5g1AX00

Arm

arm

Arm cylinder does not move

check the operation of
actuators other than of
the arm cylinder

normal

check the pilot valve

Faulty

repair or replace the pilot
valve

normal

check the spool opera-
tion

Faulty

Repair or replace the housing

block

normal

Test by replacing the port

relief valve

Problem solved

The port relief valve is
faulty

repair or replace the port re-
lief valve.

No change

check the arm cylinder.

Faulty

repair or inspect the arm cyl-
inder

1. check the operation of actuators other than of the

arm cylinder

Determine if only the arm cylinder is faulty by checking

the operation of actuators for the devices listed in the

table on the right.

if it is faulty, check the main relief valve and the hydrau-

lic pump (main).

“5. Troubleshooting, Overall machine, All systems

working, but insufficient force”

2. check the pilot valve

Disconnect the hose connecting the pilot valve and the

control valve (arm block) from the control valve. Fit the
pressure gauge to the hose just disconnected.
• Operate the lever (arm) and measure the pressure.
• If the pressure is between 0 and 3.4 MPa (0 to 493

PSI) depending on the lever angle, the pilot valve is

normal.

lever to operate

Device to check

relief valve

Pump

left travel

arm

TroubleshooTing

5g1AX00

Arm

3. check the spool operation

Disconnect the arm hose connected to the pipe at the

boom foot, then install a pressure gauge in the discon

nected hose.

• Operate the lever (arm) and measure the pressure.
• If the measured value is within the specifications, the

spool is normal.

Supply pressure: 21.0 MPa (3046 PSI)

4. Test by replacing the port relief valve

replace the port relief valve in question with a normal

port relief valve. if the arm cylinder operates with the re-
placement valve, the port relief valve used on the boom
side is faulty.

Make sure to return the port relief valve to its regular

position after the above inspection.

5. check the arm cylinder

switch between the arm hose and the bucket hose

connected to the piping at the boom foot.
• Move the lever (bucket) and try to operate the arm

cylinder.

• If the cylinder fails to operate, it is faulty.

Before performing the steps above, fully extend the

bucket cylinder, completely retract the arm cylinder

and lower the bucket to the ground.

*$)=

arm

TroubleshooTing

5g1AX00

Arm

Arm cylinder operation is slow or lacks force

is the speed of the arm
cylinder within spec?

Within spec

normal

out-of-spec

check the pilot valve

Faulty

repair or replace the pilot
valve.

normal

check the spool opera-
tion

Faulty

Repair or replace the housing

block.

normal

Test the port relief valve
with a replacement valve

Problem solved

The port relief valve faulty

repair or replace the port re-
lief valve.

No change

check for leak inside the
arm cylinder

Faulty

repair or replace the arm cyl-
inder.

1. is the speed of the arm cylinder within spec?

“2. Service data, Performance criteria”

2. check the pilot valve.

“Arm cylinder does not move, 2. check the pilot

valve”

3. check the spool operation.

“Arm cylinder does not move, 3. Check the spool

operation”

4. Test the port relief valve with a replacement valve.

“Arm cylinder does not move, 4. Test by replacing

the port relief valve”

arm

TroubleshooTing

5g1AX00

Arm

5. check for leak inside the arm cylinder

a. Fully retract the bucket cylinder and the arm cylin-

der, and then lower the bucket to the ground.

b. Disconnect the two hoses connected to the cylin-

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

c. raise the boom and lift the hoe attachment off the

ground. If the arm drops, the cylinder is faulty. If not,

there is a leak inside the control valve.

*$)=

arm

TroubleshooTing

5g1AX00

Arm

Spontaneous drop of the arm is too large

is the spontaneous drop
of the arm cylinder within
specs?

Within specs

normal

out-of-specs

check the arm cylinder

Faulty

repair or replace the arm cyl-
inder

1. is the spontaneous drop of the arm cylinder within

specs?

“2. Service data, Performance criteria”

2. check the arm cylinder

“Arm cylinder operation is slow or lacks force, 5.

check for leak inside the arm cylinder”

BuckeT

TroubleshooTing

5g2AX00

buckeT

BuckeT

Bucket cylinder does not move or lacks force

check the operation of
actuators other than of
the bucket cylinder

normal

check the pilot valve

Faulty

repair or replace the pilot
valve

normal

check the spool opera-
tion

Faulty

Repair or replace the housing

block

normal

Test by replacing the port

relief valve

Problem solved

The port relief valve is
faulty

repair or replace the port re-
lief valve

No change

check the bucket cylin-
der.

Faulty

repair or replace the bucket
cylinder

1. check the operation of actuators other than of the

bucket cylinder

Determine if only the bucket cylinder is faulty by check-

ing the operation of actuators for the devices listed in
the table on the right. If one of them is faulty, check the
main relief valve and the hydraulic pump (main).

“5. Troubleshooting, Overall machine, All systems

working, but insufficient force”

2. check the pilot valve

Disconnect the hose connecting the pilot valve and the

control valve (bucket block) from the control valve. Fit
the pressure gauge to the hose just disconnected.
• Operate the lever (bucket) and measure the pres

sure.

• If the pressure is between 0 and 3.4 MPa (0 to 493

PSI) depending on the lever angle, the pilot valve is

normal.

3. check the spool operation

Disconnect the bucket hose connected to the pipe at

the boom foot, then install a pressure gauge in the dis

connected hose.

• Operate the lever (bucket) and measure the pres

sure.

• If the measured value is within the specifications, the

spool is normal.

Supply pressure: 21.0 MPa (3046 PSI)

lever to operate

Device to check

relief valve

Pump

Right travel

BuckeT

TroubleshooTing

5g2AX00

buckeT

4. Test by replacing the port relief valve

replace the port relief valve in question with a port re-

lief valve used for a normal boom. if the bucket cylinder
operates normally with the replacement valve, the port
relief valve used on the bucket side is faulty.

5. check the bucket cylinder

switch between the arm hose and the bucket hose

connected to the piping at the boom foot.
• Move the lever (arm) to operate the bucket cylinder.
• If the cylinder fails to operate, it is faulty.

Before performing the steps above, fully extend the

bucket cylinder, completely retract the arm cylinder

and lower the bucket to the ground.

*$)=

BuckeT

TroubleshooTing

5g2AX00

buckeT

Spontaneous drop of the bucket is too large

is the spontaneous drop
of the bucket cylinder
within specs?

Within specs

normal

out-of-specs

check the bucket cylin-
der

Faulty

repair or replace the bucket
cylinder

normal

Oil is leaking inside the control

valve

Replace the housing block

1. is the spontaneous drop of the bucket cylinder

within specs?

“2. Service data, Performance criteria”

2. check the bucket cylinder

a. Fully extend the bucket cylinder, completely re-

tract the arm cylinder, and lower the bucket to the

ground.

b. Disconnect the two hoses connected to the cylin-

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

c. raise the boom and lift the hoe attachment off the

ground. If the bucket drops, the cylinder is faulty. If

not, there is a leak inside the control valve.

*$)=

TROUBLESHOOTING

BOOM SWING

5G3AX00

BOOM SWING

Swing cylinder does not move.

1. Check the operation of actuators other than of the

swing cylinder.

Determine if only the boom swing cylinder is faulty by
checking the operation of actuators for the devices
listed in the table on the right. If one of them is faulty,
check the main relief valve and the hydraulic pump
(main).

“5. Troubleshooting, Overall machine, All sys-
tems working, but insufficient force”

2. Check the spool operation.

• Spool stroke: 7 mm (0.3. in.)
• If the spool is sticking, try to take it out.

If it can’t be taken out or is scratched, replace the
housing block.
Note that the faulty spool operation could be
caused by the loosened bolt used for the return
spring.

Check the operation of
actuators other than of
the swing cylinder.

Normal

Check the spool opera-
tion.

Faulty

Repair or replace the housing
block.

Normal

Check the linkage.

Faulty

Adjust, repair or replace.

Normal

Check the anti-cavitation
valve.

Faulty

Repair or replace the anti-
cavitation valve.

Normal

Check the swing cylin-
der.

Faulty

Repair or replace the swing
cylinder.

Lever to operate

Device to check

Relief valve

Pump

Right travel

5G3AF01Z

5G3AX001

BOOm Swing

TroubleshooTing

5G3AX00

boom sWing

3. check the linkage

To check the linkage, remove the R pin (2) and pin (3)

used to connect the spool and the yoke (1) , and then
inspect the yoke (1) movement.

4. check the anti-cavitation valve

If only the right swing is inoperable, it is likely that for

eign matter is caught in the anti-cavitation valve or the
valve is sticking.

5. check the swing cylinder

Disconnect the hose connecting the swing cylinder

and the control valve from the control valve and mea-
sure the supply pressure in the control valve. if the sup-

ply pressure is normal, the swing cylinder is faulty.
• If the measured value is as below, the supply pres

sure is normal.

Supply pressure: 21.0 MPa (3046 PSI)

*$)=

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