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Abstract
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An experimental cab, provided with vertical, pitch and roll suspension, has been constructed on a 2-wheel drive tractor. Natural frequencies and damping were independently adjustable for each mode of vibration. Suspension performance was first optimized by running the tractor over two artificial bumpy tracks at several different speeds.
RESULTS, based on frequency-weighted accelerometer readings, showed that good isolation of vertical, pitch and roll vibration could be achieved with natural frequencies of 1·0, 0·6 and 0·5 Hz in the respective modes. The best performance was recorded over the smoother track, when at the highest speeds there was around 70% attenuation in each mode of vibration. The suspension was generally less effective on the rougher track, particularly at low speeds. Some field tests were also carried out and the performance was found to be very similar, except that at low speeds the isolation on a real ploughed surface was better than on the ploughed surface simulated by the rougher of the two test tracks.
RESULTS and subjective impressions indicate that cab suspension allows higher tractor speeds and sets a new standard in ride comfort and noise reduction. The benefit of one, two and three degrees of freedom is discussed against the design implications and cost. Further fieldwork under practical farm conditions is proposed to substantiate results and investigate any operational difficulties that may be experienced by the driver because of his better isolation and consequent lack of feel for the tractor's behaviour.
Language: en |