Cranfield University

Laboratory Studies Into Undercarriage Systems
compares to the case of the 680/10.5/2.2 and the 800/10.5/2.5 from Ansorge (2005, a).
Again, the higher section width tyre with similar inflation pressure as the wider tyre cre-
ated similar soil displacement. Therefore the larger section height accounts for the smaller
section width. The potential difference in carcass stiffness of cross ply (600/4.5/1.4) vs.
radial (500-85/4.5/1.4) tyre did not have an influence. The 700/4.5/1.0 tyre was not able to
utilize its large section width and low inflation pressure to create a significantly smaller
soil displacement although having the largest contact area of 0.47 m 2 .
Depth (mm)
0
100
200
300
400
500
600
700
Displacement (mm)
0 10 20 30 40 50 60 70 80
Figure 31: Soil displacement vs. depth for the rear tyres
500-70/4.5/2.3
500-85/4.5/1.4
600/4.5/1.4
700/4.5/1.0
The average increase in soil density caused by the implement tyres was similar to the
800/10.5/1.25 tyre, both increasing soil density by 12%; half the load on a smaller tyre
increased density by a similar amount to the total load at half the recommended inflation
pressure.
In order to investigate the additional soil displacement caused by the rear tyres, Figure 32
contains the soil displacement caused by the front axle on its own and after the additional
pass of the rear tyre. After the pass of a track, the extra soil displacement from the rear tyre
can be neglected. The same held true for the 900/10.5/1.9 followed by the 700/4.5/1.0.
However, if the 900/10.5/1.9 was followed by the 500-70/4.5/2.3 soil displacement in-
creased considerably. Thus, the rear tyre size was crucial in relation to soil displacement
after the pass of a soil protecting tyre, yet it was not crucial after the pass of a track as long
as the load could be carried and distributed by the strong layer at the surface created by the
track. The strong layer phenomenon originating from the track will be discussed in 7.1.
Ph.D. Thesis Dirk Ansorge (2007)
LSD
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