5-36
5
BUCKET
TROUBLESHOOTING
BUCKET
Bucket cylinder does not move or lacks force
1
Check the operation of
actuators other than of
the bucket cylinder
Normal
2 Check the pilot valve
Faulty
Repair
or replace the pilot
valve
Normal
3
Check
the spool opera-
tion
Faulty
Repair
or replace the housing
block
Normal
4
T
est by replacing the port
relief valve
Problem solved
The port relief valve is
faulty
Repair
or replace the port re-
lief valve
No change
5
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).
“5-5”
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-
sur
e.
• If the pressure is between 0 and 3.4 MPa depending
on the lever angle, the pilot valve is normal.
3. Check the spool operation
“5-32”
Lever to operate
Device to check
Relief valve Pump
Right travel
TB228, 235: R2 TB228, 235: P2
TB250: R1 TB250: P1
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