The agricultural tractor is designed as a general purpose machine and consequently, does not perform all its tasks at maximum efficiency. Various methods of increasing the field performance of these vehicles have been studied. Traction is one of the main factors limiting the field performance of the modern tractor. The process of developing traction has therefore been investigated by many researchers and although this study has resulted in a better understanding of the mechanics, it has not to any great extent assisted the operator to optimize performance in the field. It was concluded that in order to solve the problem the operator required a control system to maintain the dynamic load and inflation pressure at optimum levels. Work was carried out to develop and evaluate such a system using the Single Wheel Traction Research Vehicle at the USDA's National Soil Dynamics Laboratory in Auburn, Alabama, USA. A computer management system was developed to control the dynamic load, net traction and inflation pressure of the test tyre. During a simulated field operation the system was programmed to cycle the tyre over its operating range of dynamic load and inflation pressure while monitoring tractive efficiency. A tractive efficiency response surface was computed for the particular condition and the surface searched for the dynamic load and inflation pressure levels which resulted in maximum tractive efficiency. The tyre was then controlled and operated at maximum tractive efficiency. Evaluation showed that within the operating range of the tyre, tractive efficiency varied considerably with dynamic load, inflation pressure, net traction and soil condition. The results indicated that a considerable advantage could be obtained by using such an arrangement on a tractor. The system would automatically maximize the tractive efficiency of the tractor under the particular field conditions and with the particular implement being used. Implements could be ballasted and the hitch system used to control the weight transfer to ensure maximum tractive efficiency. Systems such as these would result in a significant improvement in the field performance of the machine and a reduction in management time required to optimize the performance of the tractor implement combination. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1991.

Call number: LD2668 .T4 1986 F86 / Master of Science / Mechanical and Nuclear Engineering