Excavation powerlessness is one of the typical failures of excavators. For small excavators or medium and large excavators, digging powerlessness can be divided into two cases: one is digging powerlessness, the engine does not hold the car, feeling the load is very light; the second is digging powerlessness, when the moving arm or bucket bar reaches the bottom, the engine seriously holds the car, or even stalls.

Crawler mini excavator

①The digging force is weak but the engine does not hold the car. The size of the digging force is determined by the output pressure of the main pump, and whether the engine holds back depends on the relationship between the absorbed torque of the oil pump and the output torque of the engine. The engine does not hold the car means that the oil pump absorbs less torque and the engine load is light. If there is no obvious abnormality in the working speed of the excavator, the focus should be on checking the maximum output pressure of the main pump, that is, the system overflow pressure. If the relief pressure measurement value is lower than the specified value, it indicates that the overload relief valve setting value of the hydraulic circuit of the mechanism is incorrect, resulting in premature overflow of the mechanism and weak work. Then the machine can be adjusted by turning the adjusting screw.

② Excavation powerlessness and engine holding. Engine holding indicates that the absorbed torque of the oil pump is greater than the engine output torque, resulting in engine overload. This fault should first check whether the engine speed sensing system is normal, the inspection method is similar to the engine inspection method described in the previous section. After the above detailed inspection and troubleshooting, the engine speed sensing system to restore normal function, the engine holding phenomenon disappears, the excavator will return to normal.