Analysis: The action of the stick is controlled by the stick reversing valve, and the movement of the stick reversing spool is affected by the following two aspects: A. The pilot oil control is slow; B. The reversing valve spool movement resistance and spring return elastic force.
There are two main reasons for the slowness of the pilot oil control. (A) The back pressure of the pilot oil of the stick directional valve is large, and (B) the reset of the stick pilot spool is slow.
Judgment method:
A. First check whether the pilot oil path of the stick directional valve is equipped with a one-way throttle valve, if there is, first remove the one-way throttle valve for cleaning, clear the damping hole or cancel the throttle valve core;
b. If the fault still exists or the pilot oil path of the stick reversing valve is not equipped with a one-way throttle valve, then replace the two pilot hoses of the adjacent working rotary valve with the stick valve, if the fault is transferred to On the rotation, the pilot valve must be repaired. If the fault still exists, it means that the pilot control is ok. The rest is the stick directional spool:
Remove the stick reversing spool and check whether the spool can slide freely and whether the spool return spring is broken (if the broken spool is loose).
Part of the control valve failure of Kobelco excavator may cause system failure:
1. Pressure compensation valve Each directional valve on the multi-way valve is equipped with a pressure compensation valve. The return oil of each actuator must flow through the corresponding pressure compensation valve back to the oil tank. If a certain pressure compensation valve core If it is stuck and cannot be reset, the oil return channel of the corresponding actuator will be closed or reduced, and the back oil of the actuator will generate a large back pressure. Even if the working pressure is 28MPa, the actuator will slow down.
Two. The charge valve boom, arm, and bucket directional valve are each equipped with a charge valve. If a charge valve spool is stuck after being opened, it cannot be reset or the damping hole of the charge valve spool is blocked, which will cause oil replenishment. The spool has always been in the open position, and the inlet and return circuits of the corresponding actuator have been connected, so the working pressure of this actuator cannot be established, and this actuator cannot be operated, or can only be slowly lowered by its own weight.
