Case Study: The Power Is Weak - Kubota KX080-3 Workshop Manual

WSM KX080-3 Service
b. Case - Study : The power is weak.
Problems
1 The entire actuator power is 1) Poor operation or maladjustment of the main relief valve
weak. 2) The unload relief valve is defective. A leak is increased.
3) Decrease in the regulator control differential pressure. Loose setscrew. 1) Readjust the LS control differential pressure.
4) Leak of pressure from the high pressure relief valve.
2 The power of a certain actu- 1) For the actuator with an overload relief valve, the relief valve operation
ator is weak. is poor or maladjusted.
2) A leak from the inside of the cylinder is increased.
(An increased leak causes work to slow down.)
3) The high pressure relief valve has got stuck.
3 The swivel actions in the 1) The pressure of the swivel motor relief valve is low.
right and left directions are
different from each other
2) The swivel pilot pressure on one side is low.
and the swivel power is
weak.
3) The stroke of the control spool is insufficient. It has got stuck on one
side.
4 The traveling power is weak 1) Poor operation or maladjustment of the main relief valve
2) Poor operation or maladjustment of the unload valve
3) Decrease in the regulator control differential pressure. Loose setscrew
4) Pressure leak from the shigh pressure relief valve.
5) The traveling lever does not full-stroke shift.
6) Pump volumetric efficiency decreased.
Fig. 9 Pilot valve, tilted
Push rod
Spring seat
Spool
Probable causes
1) Disassemble, clean and reset the main relief valve.
1) Disassemble, clean and reset the unload valve.
1) Measure the pressure. Disassemble and clean or
replace the assembly.
1) Disassemble, clean and reset the overload relief valve.
1) Disassemble and clean the cylinder. Replace the seal.
1) Disassemble and clean the control valve. Replace the
assembly if necessary.
1) Measure the swivel relief valve pressure. Readjust the
relief pressure.
1) Interchange the right and left pilot hoses to make a
check.
1) Check the sliding of the control spool.
1) Disassemble, clean and reset.
1) Disassemble, clean and reset.
1) Measure the pressure. Disassemble and clean. Replace
the assembly if necessary.
1)Disassemble, clean and reset.
1) Check the travel pilot valve.
1) Test pump efficiency and replace if needed.
Fig. 10 Control valve Fig. 11 Pressure compensation spool
Overload relief
valve
Main spool
Pressure
compensation
spool
Load check
Remedies Ref.Fig.
Fig.1
Fig.2
Fig.3
Fig.1
Fig.2
Overload relief
valve
High pressure
selection valve
Backet(Boom) section
Fig. 13 Pump control
IV-S-5
Hydraulic system