Wheel loader fault detection is confirmed by 4 processes. Wheel loader generally adopts the electromechanical-hydraulic integrated control mode. When some faults are eliminated, the problem of matching the engine, hydraulic pump, distribution valve and external load is mostly solved. Generally, in the loader operation, these aspects cannot be matched, often manifested as: the engine speed drops, the operation speed becomes slower, the powerless excavation, and some common problems.
One discovers the weak but the engine does not hold back the car. The size of the excavation force is determined by the output pressure of the main pump. Whether the engine holds back depends on the relationship between the absorption torque of the oil pump and the engine output torque. If the engine does not turn, it means that the oil pump absorbs less torque and the engine load is lighter. If the operating speed of the loader is not significantly abnormal, you should focus on the maximum output pressure of the main pump, that is, the system overflow pressure. If the measured value of the overflow pressure is lower than the specified value, it indicates that the setting value of the overload relief valve of the hydraulic circuit of the organization is incorrect, causing the organization to overflow prematurely and the operation is weak. You can adjust the machine by rolling the adjustment screw. ② Excessive powerlessness, engine holding back. Engine holding back indicates that the absorption torque of the oil pump is greater than the output torque of the engine, causing the engine to be overloaded. This problem should first check whether the engine speed sensing system is normal, and the checking method is similar to the engine checking method described above. After the above detailed inspection and troubleshooting, the engine speed sensing system recovers normal functions, and the engine holding phenomenon disappears.
Second, the operating speed is slower The main reason for the slower operating speed of the loader is the wear of various parts of the machine, which results in the decrease of engine power and the leakage of the hydraulic system. The hydraulic pump of the loader is a plunger variable pump. After the operation must be kept, the internal hydraulic components of the pump (cylinder, plunger, valve plate, nine-hole plate, turtle back, etc.) will inevitably undergo excessive wear and will cause internal leakage. The data of each parameter is not coordinated, and then the flow rate is insufficient, the oil temperature is too high, and the operation speed is slow. At this time, the whole machine needs to be overhauled to repair and replace the parts with excessive wear.
But if the loader that is operating for a long time suddenly slows down, you need to check the following aspects. First check whether the circuit fuse is open or short circuit, then check whether the pilot pressure is normal, and then check whether the servo control valve-servo piston is stuck and whether the distributor confluence is defective, etc. Finally, the hydraulic pump is disassembled for data measurement, and the excavator problem is acknowledged Where.
Third, the loader is weak. The loader's inability to excavate the inability is one of the typical problems of the loader. There are two kinds of conditions about the excavation weakness: one is the excavation weakness, the engine does not hold back the car, and the load is very light; the second is the excavation weakness, when the boom or stick extends to the end, the engine severely holds back the car, or even shuts down .
Fourth, the engine speed decline must first test the output power of the engine itself. If the engine output power is lower than the rated power, the cause of the problem may be poor fuel quality, low fuel pressure, incorrect valve clearance, an engine cylinder does not work, fuel injection There is an error in punctuality, the setting value of the fuel quantity is not correct, the air intake system leaks, the brake and its control rod are defective, and the turbocharger deposits carbon. If the output power of the engine is normal, you need to check whether the flow rate of the hydraulic pump does not match the output power of the engine.
Hydraulic loader speed and load are inversely proportional during operation, that is, the product of flow rate and pump output pressure is an invariant, and the output power of the pump is constant or approximately constant. If there is something wrong with the pump control system, it is impossible to achieve the optimal matching of the load of the engine, pump and valve in different operating conditions, and the loader will then not work normally. Such problems must start with the electrical system, then check the hydraulic system, and finally the mechanical transmission system.
