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A two-tine oscillatory subsoiler was developed at the University of South Australia for fracturing the compacted soil layers between grapevines using small tractors. As the soil forces exerted on the tines were unbalanced, the tillage forces, torque peaks through the power-take-off and the inertia of the tines transferred vibrations to the tractor and its driver. These vibrations currently prevent the commercial use of soil loosening settings that require the lowest engine power to be used.A simulation model is presented that calculates the dynamic behaviour of the tractor oscillating subsoiler system with the focus being on the vibrations at the tractor driver’s seat. The model considers the three oscillatory tillage phases of soil cutting, backing-off and catching-up, with positive and negative oscillation angles; tine inertia and the various tyre stiffness and damping parameters.The results of the simulation were compared to field measurements and a good correlation of both the magnitude of root mean square (RMS) acceleration and the response to change in the oscillatory tillage parameters of amplitude, frequency and oscillation angle were obtained. Refereed/Peer-reviewed

A deep working oscillatory subsoiler was developed at the University of South Australia to be towed by a tractor (3 t and 70 kW) in a semi-mounted configuration. During use, the soil-tool interaction forces transferred too much vibration to the tractor when operating at the desired subsoiler settings. In order to reduce the tractor vibrations, the source of vibration was studied using the power spectral density method to correlate the tractor seat vibrations to machine operating parameters. It was found that tyre lug engagement and the engine speed did not have significant effect on tractor vibration. The soil-tool interaction of both soil cutting and compaction during the oscillating motion of the tine, combined with the torque peaks on the driveline from the power take-off to the tines, had the dominant effect on vibration.

In established Australian vineyards compacted soil either created naturally or by trafficking prevents root growth to desirable depths and restricts root systems from getting water and nutrients. This can reduce the life span and productivity of grapevines considerably over a period of years. To break up these compacted soil layers using small tractors a deep working oscillatory ripper was developed at the University of South Australia which had two deep working oscillating tines. One of the most important factors for the performance of this oscillatory ripper is the oscillation angle of the tines. To find the optimum oscillation angle a series of field tests were conducted in a sand-loam soil at six different oscillation angles. The tines oscillated at a frequency of 4.9 Hz and with amplitudes of between ±60 and 69 mm, with a nominal forward speed of 3 km/h. The trial results were quantified as draft requirement, power saving, power ratio, loosened area and amount of vibration on tractor seat. The greatest draft reduction of 50% was achieved for negative oscillation angles, where power ratio was less than 1. Power saving was significantly affected by changing oscillation angle. In general, vibration of the driver seat was higher for negative angles. In terms of performance −22.5° oscillation angle was the optimum for draft reduction and power saving, whereas the least vibration was obtained at an oscillation angle of +16° which was equal to Australian Standard threshold for 8 h continuous work. Refereed/Peer-reviewed