Modern excavators generally adopt electro-hydraulic integrated control mode. When troubleshooting some faults, most of them are the matching problems of engine, hydraulic pump, distribution valve and external load. Generally, these aspects cannot be matched in excavator operation, which is often manifested in the decrease of engine speed, slow working speed, weak excavation and some common problems. This article will explain how to deal with the digging weakness caused by the matching problem for reference only.
Digging weakness is one of the typical faults of excavator. There are two situations for weak excavation: one is that the engine speed does not decrease and the load is very light. Second, when the boom or stick extends to the bottom, the engine speed drops seriously or even stops.
1) The excavation is weak, but the engine speed does not decrease.
The digging force is determined by the output pressure of the main pump. Whether the engine speed decreases depends on the relationship between the absorption torque of the oil pump and the output torque of the engine. If the engine speed does not decrease, it means that the torque absorbed by the oil pump is small and the engine load is light. If there is no obvious abnormality in the working speed of the excavator, focus on checking the maximum output pressure of the main pump, that is, the system overflow pressure. If the measured value of overflow pressure is lower than the specified value, it indicates that the set value of overload overflow valve in the hydraulic circuit of the excavator is incorrect, resulting in premature overflow and inability to work. The machine can be adjusted by turning the adjusting screw.
2) The excavation is weak and the engine speed drops seriously.
The decrease of engine speed indicates that the absorption torque of the oil pump is greater than the output torque of the engine, resulting in engine overload. For this fault, first check whether the engine speed sensing system is normal, and the inspection method is similar to the engine inspection method above. After the above inspection and troubleshooting, the engine speed sensing system returns to normal function, the engine speed drop disappears, and the excavation force will return to normal.
