Browsing by Author "Ansorge, Dirk"
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Item Open Access Comparison of soil compaction below wheels and tracks(2005-10-19) Ansorge, Dirk; Godwin, R. J.This study investigated the effect of high axle loads carried on self propelled wheels and tracks on soil bulk density, soil deformation, rut depth, and penetrometer resistance under controlled laboratory conditions. Furthermore pressure distribution below a three and a two idler track was measured. A brief field study was also conducted to compare the results gained under laboratory conditions. The benefit of the “Terra Trac” driving systems compared to wheel type systems was clearly shown in uniform and stratified soil conditions. Soil deformation was reduced to 50 % for the tracks compared to the wheels at an overall load of 12 t and 10.5 t, respectively. Penetrometer resistance showed a very high resistance close to the surface for the tracks. In uniform soil conditions there was no significant increase in penetrometer resistance compared to the control below 400 mm depth. Reducing the inflation pressure to half the recommended inflation pressure reduced soil deformation by 25 %. Three passes of a tire increased soil density by 20 % compared to a single pass. The three idler track showed only a 50 % increase in pressure from the front to the rear sprocket compared to a 100 % increase for the two idler track. Single peaks in pressure below each idler were less pronounced for the three idler track. Unfortunately the advantage in the pressure distribution for the three idler track did not lead to significant improved behavior concerning soil compaction. The advantage of a tracked combine compared to a wheeled combine is also shown in field measurements. The root system of oil seed rape in former track ruts is more developed than in former wheel ruts. Soil physical properties after the passage were compared to the predictions of two models. The tendency was correct, however the real values were largely offset.Item Open Access The effect of tyres and a rubber track at high axle loads on soil compaction, Part 1: Single axle-studies(Elsevier, 2007-09) Ansorge, Dirk; Godwin, R. J.One option for ground drive systems with large harvesting equipment is to use rubber-belted tracks; however, little is known about the performance of these systems relative to appropriately sized pneumatic tyres. The effect of self-propelled wheels and a track with high axle loads (9–24 t) on soil compaction were studied. Soil displacement and soil density changes were assessed by embedding talcum powder lines as tracer into the soil during preparation. In addition, soil dry bulk density and penetrometer resistance were measured. The track with loads of both 10.5 and 12 t compacts the soil less than wheels at a 10.5 t load in both weak uniform and stratified soil. Towed implement wheels with a 4.5 t load caused similar soil displacement to the track with a load of 12 t. Tyre inflation pressure had a significant influence on soil parameters. To reduce compaction a larger overall diameter was found to be more beneficial than a wider tyre. This emphasised the importance of contact pressure and its distribution with respect to soil density changes. Total axle loads are less important than how these loads are distributed on the ground.Item Open Access The effect of tyres and a rubber track at high axle loads on soil compaction-Part 2: Multi-axle machine studies(Elsevier, 2008-03) Ansorge, Dirk; Godwin, R. J.This paper reports on a study of the effect of the passage of multi-axle harvesting machines on the soil physical properties. In particular, it investigates the effect of the rear tyre of a combine harvester on the amount of soil compaction subsequent to the passage of the front tyre/track. The work was conducted in controlled laboratory conditions to determine the effect of a simulated self-propelled combine harvester with a total machine weight of 30–33 t. This was assessed by embedding talcum powder tracer lines in the soil to measure soil displacement and soil density changes. Dry bulk density and penetrometer resistance were also measured. The results showed that the benefit of the rubber track found by Ansorge and Godwin [2007a. The effect of tyres and a rubber track at high axle loads on soil compaction: Part 1: Single Axle Studies. Biosystems Engineering 98 (1), 115–126] was maintained after the additional passage of the rear tyre. After the passage of a track the effect of rear tyre size was insignificant, but the rear tyre size had a significant influence on soil density when following a leading tyre. This was due to a higher strength layer at the soil surface created by the track which was able to withstand the load of the subsequent passes and protect the soil below from further compaction. Results similar to those found for a tracked machine were also achieved by three passes of a 900 mm section width tyre at 5 t load and 0.5 bar inflation pressure. The track results for the 33 t machine were very similar to those of a smaller combine harvester with a total load of 11 t and similar rut width. The study confirmed the benefit of tracks with regard to soil compaction and emphasised the fact that total axle loads and machine weights are less important than how the loads are distributed to the soil.Item Open Access Soil reaction to heavily loaded rubber tracks and tyres(Cranfield University, 2007-10-12) Ansorge, Dirk; Godwin, R. J.The importance of undercarriage design with respect to its effect on soil density changes grows with the size of harvest machinery. Therefore this study elucidates the mechanics of soil displacement caused by different undercarriage systems of combine harvesters on soil. The soil displacement caused by different undercarriage systems at maximum working weight was measured by embedding tracers into the soil in both the soil bin laboratory and the field studies. The effects of different tyres, tracks, and whole undercarriage systems on soil density increase were significant. The results from whole machine systems were validated with field experiments using fish-hooks for measuring displacement on a sandy loam and a clay soil. The draught force of a tine loosening the soil after the passage of whole machines was also investigated. With an increase in speed, soil density increase was reduced. The implement tyre evaluation emphasized the importance of tyre width, diameter, and inflation pressure on soil density increase. The evaluation of whole machine systems showed that the influence of rear tyre size on additional soil density increase is larger for wheeled than for tracked undercarriage systems. The strong layer at the surface from a track is able to carry the rear tyre without further compaction of the soil below leading to an overall soil displacement similar to a wheeled machine of 1/3 of the weight. The evaluation of different track systems emphasized the effect of the number of rollers on soil physical parameters. Variations in a high belt tension range showed only small effects. A novel approach was developed determining virgin compression line parameters in-situ from contact pressure, rut and working depth enabling an easy adjustment of a model to given soil conditions and a successful prediction of soil displacement for tyres. The in-situ approach can be used for tracks, but a different VCL results. The in-situ VCL was validated with small scale plate sinkage tests and compared to results from triaxial cell testing. Results from triaxial tests showed that the VCL depends on the relation of major and minor principel stresses. Ancillary experiments were carried out to shed light on longitudinal soil movement and the influence of lugs and pressure history on soil displacement. In addition a new heuristic model involving load per perimeter length was tested and the “punching failure” of soil observed justified with theories from literature. Ancillary experiments showed that the dense layer at the surface from the tracks originates from a backward soil movement limited to the uppermost 150 mm. The lug influence of both tyres and tracks was insignificant from 200 mm depth downwards. From heuristical data analysis the load per perimeter length was identified as an important variable. Peaked pressure history caused about 1/3 more sinkage than constant contact pressures.