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 what to do about the engine speed drop caused by matching problems for reference only.
First, test the output power of the engine itself. If the output power of the engine is lower than the rated power, the fault may be caused by poor fuel quality, low fuel pressure, wrong valve clearance, one or more cylinders of the engine do not work, wrong injection timing, wrong setting value of fuel quantity, air leakage of intake system, failure of brake and its control lever and carbon deposition of turbocharger. If the engine output power is normal, you need to check whether the flow of the hydraulic pump does not match the output power of the engine.
In operation, the speed of hydraulic excavator is inversely proportional to the load, that is, the product of flow and pump output pressure is an invariant, and the output power of pump is constant or approximately constant. If the pump control system fails, the load optimal matching state of the engine, pump and valve in different working conditions can not be realized, and the excavator will not work normally. Such faults should start with the circuit system, then check the hydraulic system, and finally check the mechanical transmission system.
