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Description
For given wheel loads, the ground pressure exerted by off-road vehicles such as forwarders is to a large extent influenced by tire width and tire inflation pressure. Thus, wide flotation tires, but also flotation bogie tracks, are well-established means of reducing soil disturbance and maintaining machine mobility in forest operations. While reduced tire inflation pressures applicable in forest operations are still higher than those common for agricultural tires during field traffic, there is some development towards lower allowable inflation pressures for forestry tires as an alternative to flotation tracks in certain applications. In this context, the distribution of ground pressure under a driving forwarder was measured with two types of low-pressure tires with nominal section widths of 0.94 m and 0.75 m and with inflation pressures of 1.2 bar and 2.5 bar, as well as with standard tires (nominal section width: 0.71 m; inflation pressure: 5.5 bar) and with flotation bogie tracks (track-plate width: 0.92 m) installed on standard tires. Foil sensors with a spatial resolution of 9.7 mm were used for measurement, and measurements were made for the rear wheels of an eight-wheel forwarder which had wheel loads of 4.5 metric tons. Observed mean and peak ground pressures followed the expected trend and decreased with increasing contact width and decreasing inflation pressure. Thus, observations were consistent not only with previous findings from static measurements of ground-pressure distribution but also with results from field experiments.
| Keywords | vehicles; terramechanics; soil; stress |
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