JST Vol. 21 (1) Jan. 2013 - Pertanika Journal - Universiti Putra ...
JST Vol. 21 (1) Jan. 2013 - Pertanika Journal - Universiti Putra ...
JST Vol. 21 (1) Jan. 2013 - Pertanika Journal - Universiti Putra ...
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Ahmad, D., Jamarei, O., Sulaiman, S., Fashina, A. B. and Akande, F. B.<br />
TABLE 5(a): Motion resistance ratios obtained from the empirical approach<br />
Added Dynamic<br />
Load (N)<br />
98.1<br />
196.2<br />
392.4<br />
588.6<br />
Tilled Surface Wet Surface<br />
Pneumatic Rigid Pneumatic Rigid<br />
0.0878 0.1778 0.2540 0.3180<br />
0.1108<br />
0.1041<br />
0.1116<br />
0.1704<br />
0.1818<br />
0.2431<br />
0.2250<br />
0.2332<br />
0.1945<br />
TABLE 5(b): Motion resistance ratios obtained from the analytical approach<br />
Added Dynamic<br />
Load (N)<br />
98.1<br />
196.2<br />
392.4<br />
588.6<br />
Tilled Surface Wet Surface<br />
dynamic loads which showed poor mobility.<br />
From the semi-empirical approach, it is difficult to conclude the nature of the relationships<br />
that existed between the motion resistance ratios and the dynamic loads. However, the motion<br />
resistance ratios predicted were directly proportional to the added dynamic load for both the<br />
wheels, except for the pneumatic wheel which exhibited an inverse relationship between the<br />
motion resistance ratio and the added dynamic load. The motion resistance ratios under this<br />
condition fell under a good mobility classification.<br />
Fig.3 and Fig.4 show the graphical relationships between the motion resistance ratios<br />
and the towing velocities of both the wheels on the tilled and wet surfaces, respectively,<br />
based on the empirical data. The mathematical relationships between the motion resistance<br />
ratio and their towing velocities are presented in Equations 8 to 11. On the tilled surface, the<br />
motion resistance ratios of both the wheels had direct relationships with the towing velocity.<br />
This could also be inferred from the equation having positive coefficient of towing velocity<br />
(v). The pneumatic wheel also showed a similar relationship on the wet surface with a higher<br />
coefficient of regression. As shown in Fig.4, when the towing velocities increased, the motion<br />
resistance ratio of the rigid wheel would decrease. This can also be seen in Equation 11, where<br />
68 <strong>Pertanika</strong> J. Sci. & Technol. <strong>21</strong> (1): 283 - 298 (<strong>2013</strong>)<br />
0.3513<br />
0.2605<br />
0.2637<br />
Pneumatic Rigid Pneumatic Rigid<br />
0.1091 0.1052 0.0903 0.1245<br />
0.1014<br />
0.0977<br />
0.1002<br />
0.1098<br />
0.1431<br />
0.1792<br />
0.0897<br />
0.0934<br />
0.0984<br />
TABLE 6: Motion resistances of pneumatic and rigid wheels measured empirically<br />
Added Dynamic<br />
Load (N)<br />
98.1<br />
196.2<br />
392.4<br />
588.6<br />
Tilled Surface Wet Surface<br />
0.1323<br />
0.1472<br />
0.1503<br />
Pneumatic Rigid Pneumatic Rigid<br />
28.2374 57.8055 81.7383 103.4037<br />
46.5073<br />
64.1054<br />
90.6656<br />
72.1290<br />
112.5968<br />
198.3133<br />
94.4724<br />
143.6779<br />
157.9837<br />
148.7016<br />
161.3703<br />
<strong>21</strong>5.0599
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