Relief Valve, Unload Valve And High Pressure Selector Valve Troubleshooting; General Hydraulic System Troubleshooting - Kubota KX080-3 Workshop Manual

WSM KX080-3 Service
--Relief valve, unload valve and high pressure selector valve --
Trouble
1. Pressure will not be raised at all.
2. Relief pressure is unstable.
3. Relief pressure is out of the preset
range.
4. Oil leaks.
--General hydraulic system --
Trouble
1. Hydraulic system malfunctions or
does not function at all.
Possible cause
1. Main poppet, sleeve or pilot poppet
is seized and kept open, or dust exists
at the valve seat.
1. Seat of the pilot poppet is damaged.
2. Piston or main poppet is seized.
1. Abrasion of seat by dust.
2. Lock nut and adjuster are loosened.
3. Pressure regulating nut of the
unload valve is loosened.
4. Spool of the unload valve is seized
and kept open, or dust exist at the
spool of the unload valve.
5. High pressure selector valve is
damaged.
6. High pressure selector valve plate
is seized.
1. Relief valve seat is damaged.
2. Parts are seized by dust.
3. Abrasion of O-ring.
Possible cause
1. Trouble with pump
2. Trouble with relief valve
3. Trouble with cylinders
4. Pump load pressure is too high.
5. Valve is cracked.
6. Spool does not stroke.
7. Oil level in the oil tank is too low.
8. Filter in the circuit is clogged.
9. Pipes in the circuit are choked.
IV-S-17
Hydraulic system
Remady
Replace the relief valve.
Re-set the pressure and tighten the
lock nut with specified torque.
Re-set the pressure and tighten the
lock nut with specified torque.
Replace either of the spool of the
unload valve or the inlet housing, or
replace both.
Replace the High pressure selector
valve plate or the section assembly.
Replace the relief valve.
Replace the adjuster or O-ring of
valve mounting part.
Remady
Check oil pressure, or replace the
pump.
Replace the relief valve.
Repair or replace.
Check the pressure in the circuit.
Replace the valve in assembly.
Check the spool motion.
Add hydraulic oil.
Clean or replace the filter.
Check pipes.