Vibroacoustic optimization of a tractor cab

The wide spread of tractors (almost 1.9 million of units only in Italy) and the very high noise and vibration levels at the driver position, make noise and vibration control a key issue. Long exposures to high noise levels and all-body vibrations, indeed, are major factors of risk to worker health and safety. On the other hand, noise and vibration regulations at workplaces are more and more stringent and tractor manufacturers must comply with existing standard requirements to place their machines on the market. This paper describes the results of a joint project between an Italian tractor manufacturer and IMAMOTER Institute, aimed at developing efficient strategies to improve the noise and vibration emissions inside the cabin of a tractor prototype. The initial "minimum" target identified by the manufacturer was a reduction of the noise level at the driver's ear position of about 3 dB. In order to achieve this target, a methodological approach was fully developed. It was grounded on an accurate vibroacoustic investigation of the machine, based on the integration of noise and vibration tests and numerical analyses. This successful approach led to better results than expected, with significant noise reductions both inside the cabin and in the environment and also with a significant decrease of the vibrations transmitted into the cabin.