A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1980

The factors relating trafficability of flat lugged cage wheels operating on wet saturated soils has been studied. A theoretical model was developed to describe the pull and lift characteristics of cage wheel with respect to lug spacing, lug angle, slip, and sinkage. Experiments on a model of a caged wheel has performed in order to validate the theoretical model. The experimental cage wheel was designed with the capacity to change lug angle (O - 40 deg at the intervals of 10 deg) and lug spacing (20, 30, 40 and 60 deg). Tests on drawbar performance of the wheels were conducted in an experimental puddled plot, where the designed cage wheels were fitted to a 11.4 KW tractor manufactured in Thailand. The experimental results revealed that for a cage wheel of 0.88 m, diameter with lugs of 0.10 m height will provide optimum trafficability about 30 deg lug spacing, and 25-30 range of lug angle. The theoretical model for lift forces did not satisfy the actual conditions where for sinkage values less than the wheel radius (0,44 m). The model showed the soft (with 2cm standing water) top soil layer cannot provide a sufficient lift force to bear the weight of the rear wheels. So it has been concluded that the theoretical analysis concerning the interaction of lug with the hardpan should be done. The theoretical model showed a similar variation in the relationship between draught and lug angle/lug spacing, beyond the lug spacing of 30 deg. Due to the problem of mud trapping in between the lugs, the experimental values for 20 deg lug spacing were very low at all of the lug angles. Except in the case of 20 deg lug spacing, the cage wheel showed better tractive performance than the commercially available cage wheels.