1. The engine speed drops
First, test the output power of the engine itself. If the output power of the engine is lower than the rated power, the cause of the failure may be poor fuel quality, low fuel pressure, incorrect valve clearance, an engine cylinder does not work, the injection timing is wrong, fuel The set value is not correct, the air intake system leaks, the brake and its control rod are defective, and the turbocharger deposits carbon.
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. The hydraulic excavator's speed is inversely proportional to the load in the operation, that is, the product of the flow rate and the output pressure of the pump is an invariant, and the output power of the pump is constant or approximately constant.
If the pump control system fails, it is impossible to achieve the optimal matching of the load of the engine, pump and valve in different working conditions, and the excavator will not work properly. Such failures must start with the electrical system, then check the hydraulic system, and finally check the mechanical transmission system.
2. The working speed becomes slow
The working speed of the excavator is slowed down mainly due to the wear of various parts of the whole machine, which causes the engine power to drop and the hydraulic system to leak. The hydraulic pump of the excavator is a plunger variable pump. After working for a certain period of time, the internal hydraulic components of the pump (cylinder, plunger, valve plate, nine-hole plate, turtle back, etc.) will inevitably produce excessive wear and will cause internal leakage. The data of each parameter is not coordinated, which results in insufficient flow, excessive oil temperature and slow working speed. At this time, the whole machine needs to be overhauled to repair and replace the parts with excessive wear.
But if the excavator is not working for a long time, the sudden action is slow, 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, then see if the servo control valve-servo piston is stuck and whether the distributor confluence is faulty, etc. Finally, the hydraulic pump is disassembled for data measurement to confirm the excavator problem .
