Kubota KX080-4 Workshop Manual page 327

KX080-4, WSM
Won't switch to high-speed travel
• Check whether the travel speed switch is switching in the tester mode.
No. Cause
Faulty 2nd speed solenoid valve at
1 unload unit
• Defective travel motor
• Swivel joint faulty
2
[4] SWIVEL SYSTEM TROUBLESHOOTING
When the swivel is slow, fails to work or is jerky.
• Identify whether the fault is in the main system or the pilot system.
No. Cause
Defective pilot valve
1
Slow return valve faulty
2
Timer valve sticking or damaged
3
Swivel shuttle valve faulty
4
Swivel relief valve faulty
5
Anticaviation valve faulty
6
Swivel motor faulty
7
Main spool inside control valve
sticking or damaged
8
Remedy
• Check 2nd speed solenoid valve operation
1. Check whether there is electricity to the unload valve.
2. Check whether the spool is switching inside.
• Measure the pressure at the travel motor 2-speed switch port.
[Assessment]
Rated pressure: travel motor faulty
Below rated pressure: swivel joint faulty
Remedy
• Measure the pilot secondary pressure
Clean or replace the slow return valve
Clean or replace the timer valve
• Measure the timer valve release pressure
(When swivel left/right, or at arm crowd)
• Clean or replace the swivel shuttle valve
• Temporarily swap the left/right swivel relief valves.
[Assessment]
If the problem changes sides: swivel relief valve faulty
If problem is the same: the main spool is sticking or damaged or the
anticavitation valve and/or swivel motor are faulty
• Swap anticavitation valves
[Assessment]
If the problem changes sides: anticavitation valve faulty
If problem is the same: the main spool is sticking or damaged or the
swivel motor is faulty
• Measure the drain volume
• Inspect the main spool or replace the valve
1. Take the main spool out of the control valve and clean it.
2. After applying hydraulic oil, check whether it slides properly and
return to the control valve.
3-S168
HYDRAULIC SYSTEM
Notes
RY9212148HYS0366US0
Notes
RY9212148HYS0367US0
KiSC issued 08, 2015 A