As an important mechanical equipment in engineering construction, the normal operation of the excavator engine is crucial. The excavator engine mainly works through the following four processes.
The first is the intake stroke. The air is sucked into the engine through the air filter. This process can remove dust and impurities in the air and ensure that the air entering the engine is clean. The air is then mixed with the atomized fuel sprayed from the fuel injection system to form a combustible mixture. For second-hand dealers, when purchasing a second-hand excavator, the condition of the air filter will be checked. If the filter is severely blocked or damaged, it may mean that there is a problem with the engine's intake system, which in turn affects the performance and life of the engine. When selling second-hand excavators, second-hand dealers can emphasize to customers the importance of regularly replacing the air filter to ensure the normal intake of the engine.
Next is the compression stroke. The piston moves upward and compresses the combustible mixture into the combustion chamber. Compression causes the temperature and pressure of the mixture to rise sharply, preparing for the upcoming combustion. When evaluating second-hand excavators, second-hand dealers will pay attention to parameters such as the engine's compression ratio. If the compression ratio is abnormal, it may indicate wear or failure inside the engine. They will determine the value and repair cost of the equipment based on these conditions, and truthfully explain the compression performance of the engine to customers when selling.
Then comes the combustion stroke, also known as the power stroke. At the end of the compression stroke, for gasoline engines, the fuel is ignited by the spark plug; for diesel engines, the air temperature is raised by a high compression ratio, and ignition is self-ignited. The fuel burns rapidly, producing high-temperature and high-pressure gases. These gases expand and push the piston downward, transmitting power to the crankshaft through the connecting rod, causing the crankshaft to rotate, thereby generating mechanical energy. Second-hand dealers will pay attention to the performance of the engine during the combustion stroke, such as whether there is knocking, whether the power output is stable, etc. If problems are found, corresponding repairs or adjustments will be made to ensure that the second-hand excavator can work properly after the sale.
Finally, there is the exhaust stroke. The piston moves upward again, expelling the burned exhaust gas from the combustion chamber. The exhaust gas is discharged from the engine through the exhaust valve, enters the exhaust system, and is finally discharged into the atmosphere. Second-hand dealers will check the condition of the exhaust system, including whether the exhaust pipe is leaking and whether the exhaust gas meets the standards. If there are problems with the exhaust system, it may affect the performance and environmental protection requirements of the engine. When selling used excavators, second-hand dealers can tell customers how to keep the exhaust system in good condition, such as regularly checking and cleaning the exhaust pipe, replacing damaged parts in time, etc.
In short, it is very important for second-hand dealers to understand the working principle of the excavator engine. They can provide customers with reliable second-hand excavators and provide relevant maintenance suggestions to extend the service life of the equipment by inspecting and evaluating each working stroke of the engine.