The excavator boom can only be raised, not lowered.
main cause:
(1) Pilot valve failure
(2) Boom linkage main valve internal failure
(3) Boom hold valve fault diagnosis process:
Step 1: check whether the outlet pressure of the pilot valve is normal. If not, repair or replace it.
Step 2: check whether the boom main coupling valve core is stuck.
Step 3: disassemble and inspect the boom holding valve, repair the excavator or replace the damaged parts.
Boom drops slowly.
main cause:
(1) Pilot valve failure
(2) Boom hold valve failure
(3) Internal fault diagnosis process of boom linkage main valve:
Step 1: check whether the outlet pressure of the pilot valve is normal. If not, repair or replace it.
Step 2: check the boom holding valve. If it is abnormal, clean or replace the boom holding valve.
Step 3: check whether the boom main coupling valve core is stuck. If it is abnormal, find out the cause of the fault and eliminate it.
The stick moves slowly and the excavation is weak
main cause:
(1) Pilot valve failure
(2) Overload makeup valve failure
(3) Main valve failure
(4) Cylinder fault diagnosis process:
Step 1: detect the pressure at the outlet end of the stick pilot control valve. If the measured pressure is abnormal, it is the failure of the stick pilot valve. Repair or replace it.
Step 2: check the overload oil make-up valve of the main valve stick linkage and exchange the overload oil make-up valve. If the stick moves normally, it indicates that the overload oil make-up valve is faulty.
Step 3: check the main valve and check whether the stick main coupling and stick confluence auxiliary coupling act at the same time. Cut off the pilot oil circuit of stick confluence and auxiliary coupling to make the main coupling act independently. The extension time of oil cylinder is compared with that before replacement: the extension time remains unchanged, indicating that the stick confluence auxiliary coupling is faulty; Longer time indicates normal confluence; If the oil cylinder does not move or moves very slowly, it indicates that the main coupling is faulty. Check the valve core of the main coupling.
Step 4: check whether the oil cylinder is faulty according to the sinking amount of the oil cylinder. If the oil cylinder is faulty, repair or replace it.
