Xugong hbc90k 1 Vehicle-mounted pump fault consultation: Hello, the oil cylinder of my pump truck shifts and the piston pushes during the process of conveying concrete.

1. Please explain that this pump truck is an open oil circuit? Or closed oil circuit? Because Xugong has two systems, I don't know which one you are. 2. Literally, there seems to be air in the transmission oil chamber. Can you hold down the pump for a minute while pumping to see if there is any improvement? 3. When pumping, check whether the piston rod retracts when stopping pumping. Ask me when you have it.