The excavator boom can only be raised, not lowered.
Main reasons:
(1) Pilot valve failure
(2) Internal failure of the main valve of the boom
(3) Trouble diagnosis process of boom holding valve:
The first step: check whether the outlet pressure of the pilot valve is normal, if it is not normal, it should be repaired or replaced.
Step 2: Check whether the main spool of the boom is stuck.
The third step: dismantle the boom holding valve, repair the excavator or replace the damaged parts.
The boom fell slowly.
Main reasons:
(1) Pilot valve failure
(2) Boom holding valve failure
(3) The internal fault diagnosis process of the main valve of the boom joint:
The first step: check whether the outlet pressure of the pilot valve is normal, if it is not normal, it should be repaired or replaced.
Step 2: Detect the boom holding valve. If abnormal, clean or replace the boom holding valve.
The third step: check whether the main spool of the boom is stuck, if it is not normal, find out the cause of the failure and eliminate it.
Stick action is slow, digging is weak
Main reasons:
(1) Pilot valve failure
(2) Overcharge valve failure
(3) Main valve failure
(4) Fault diagnosis process of cylinder:
The first step: detect the pressure at the outlet end of the stick pilot control valve. If the measured pressure is abnormal, the stick pilot valve is faulty and repaired or replaced.
The second step: detect the main valve stick-connected overload charge valve and exchange overload charge valve. If the action of the stick is normal, it means the overload charge valve is faulty.
The third step: check the main valve, check whether the stick main joint and stick joint sub-link act simultaneously. Cut off the oil confluence of the stick and auxiliary pilot, and make the main joint act independently. The extension time of the cylinder is compared with the extension time before replacement: the extension time remains unchanged, indicating that the joint of the joint of the stick is faulty; ; The cylinder does not move or moves very slowly, indicating that the main coupling is faulty. Check the main coupling spool.
The fourth step: detect whether the cylinder is faulty according to the sinking amount of the cylinder, if it is faulty, it should be repaired or replaced.
