The lifting motion of the excavator boom is too slow

A customer from Yunnan purchased it in 2008Kobelco excavatorWhen the machine is working, the lifting action of the boom is slow and intermittent, while other actions are normal.

Analyze the reasons:

After arriving at the site, the after-sales service diagnostic observation was called out. When the boom failed to act, the data of its high pressure sensor and low pressure sensor were abnormal. The pressure of the high pressure sensor of P1P2 pump was only 3M, and the pressure value of the low pressure sensor of B-1 was only 1M. After the SE3 and SE8 sensors were exchanged, the phenomenon still existed. After the high pressure sensor was replaced, the fault did not disappear. The pressure of the boom ascending pilot oil circuit was always low, so it was concluded that there was a pressure relief point in the boom ascending pilot oil circuit.
1. Swap the left and right pilot operation handles in the cab, and the phenomenon still exists, proving that there is no pressure leakage here.
2. Check the 17 one-way throttle valve for blockage.
3. Exchanging the pilot oil pipes for the lifting of the upper arm and the recovery of the lower arm is equivalent to introducing another pilot oil with a pressure of 3M to push the valve core of the upper arm. As a result, the introduction of this (which was originally normal) led to a low pressure value of only about 1M for the SE7 low-pressure sensor, indicating a leakage in the valve core of the upper arm.

Handling method:Replace the valve core of the boom and the fault disappears.