How to troubleshoot the system oil circuit failure when the excavator boom truck is weak

It is common for the boom truck to be weak or even unable to support the excavator. However, depending on the severity of the situation, the owner will choose to repair immediately or postpone the repair. However, the premise is that other actions of the excavator are normal and the construction time is urgent. This is mostly due to the failure of the oil circuit of the boom lowering system. To troubleshoot this fault point, we need to understand the design principle of the combined oil circuit of the boom lowering. Since each brand of excavator may design different oil circuit execution methods, this method is only for reference.
When the angle between the boom and the stick is 90~110 ° and the bucket is on the ground, the pressure at the bottom of the boom cylinder becomes low during the boom lowering operation and the boom lowering inlet shutoff valve is moved. Because the boom lowering pilot pressure is released, the boom flow control valve and the boom flow control valve are opened. The boom lowering pilot pressure moves the boom valve column. Pressure oil from the pump flows through the other boom valve column. The pressure oil from the other pump combines with the pressure oil from the other pump valve column through the pump valve column, and the combined pressure oil flows to the piston rod side of the boom cylinder.