Engine vibration and noise are the largest sources of loader vibration and noise. The exciting force on the diesel engine can be divided into the direct excitation force generated by the combustion and the mechanical force when the diesel engine is working.
The noise on diesel engines can be divided into three categories according to the mechanism they generate, namely aerodynamic noise, combustion noise and mechanical noise, while aerodynamic noise in exhaust systems is usually the main source of noise. Generally, if By effectively reducing the exhaust noise of the diesel engine, the total noise level of the diesel engine can be greatly reduced.
Under normal conditions, the diesel engine noise rises linearly with the increase of its rotational speed. For every 10 times increase in the speed of the naturally aspirated four-stroke diesel engine, the noise is increased by 30 dB(A), and for every four times of the four-stroke supercharged diesel engine, the noise increase is 40 dB. If the noise peak wave appears during the speed increase process, which is the problem in the noise source identification, the 1/3 octave frequency spectrum analysis can be used to initially identify the main noise components.