Reduction of noise in an excavator cabin using order tracking and ultrasonic leak detection

Abstract

During operation, heavy construction equipment can generate high levels of noise, which can adversely affect the health and job performance of operators. This study examined the noise transmitted into the operator's cabin of a crawler excavator during operation. The sources of the noise generated by the excavator and the air-borne and structure-borne transmission paths into the cabin of the excavator were identified and characterized. Order tracking, which utilizes tachometer measurements to relate the occurrence of an event to a multiple of engine rotational speed, was used to identify noise and vibration components related to excitation from the excavator's engine and hydraulic systems. The results of the analysis showed 1st order engine rotational imbalance, 3rd order engine combustion, and 9th and 18th order hydraulic pressure fluctuations were the primary components of noise and vibration generated by the excavator. An ultrasonic leak detector was used to identify small sound leaks into the cabin. Finally, passive noise control treatments were designed to attenuate and dissipate the acoustic energy transmitted into the excavator cabin. These cabin noise control treatments included covering the floor with an acoustic barrier, adding damping to the windows, lining the ceiling and walls with absorptive foam, and sealing leaks found along window, door, and panel edges. Experimental results showed that the noise control treatments reduced the overall A-weighted sound pressure level in the cabin by up to 3 dB.