Tractor cab noise reduction : final design report

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Leachman, Jeffrey
Rempel, Brendan
Gill, Sarby
Lacoursiere, Peter
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This report has been prepared as the final product of a noise reduction project for the Versatile 280 tractor cab. Team Pindrop, as requested by Versatile, looked into the acoustical noise problems with this tractor model and set out to measure and define the technical noise problems in the tractor. A measurement phase had to be completed before any designs that address the noise problems could be made. Measurements made by team Pindrop include sound pressure level readings of the tractor under load and no-load conditions, as well as accelerometer measurements of various areas. These measurements enabled the identification of problem noise sources, as well as the establishment of the sound transmission paths allowing for the design phase of the project to begin. Through analysis of the measurements the muffler stack was found to be the leading source of noise. Other components in the tractor design which lead to high noise levels in the cab have also been found and addressed in this report. After conducting research and developing a thorough list of different design options available, the best options based on highest sound attenuation for lowest capital costs were selected. The selected designs include focusing on the noise source itself, by redesigning the muffler, as well as increase sound transmission losses from the exterior to interior of the cab by adding acoustic insulation and vibration damping. The muffler should be redesigned to exhaust at lower sound levels while the insulation added to the ceiling will help to attenuate the increased sound levels by the blower fan for the climate control system. Because of the complexity of the mechanical systems involved in a tractor, it is difficult to isolate and characterize the specific noise sources. This complexity makes it difficult to predict the affects of implementing a single design in the tractor, and thus, an overall noise level reduction for each option is not available. The effectiveness of various designs will only be known after implementing them and testing for the associated noise reduction. Therefore, team Pindrop recommends that Versatile implement and test the different design options to identify the most suitable combination for production.
tractor, cab, noise, reduction