DEVELOPMENT OF A SLIP METER FOR TRACTORS REVIEW OF LITERATURE For developing a slip meter one must know what are the optimum working ranges of slip for better traction and minimum fuel consumption. Also one must review what work has been done till present in this field of developing a slip meter. Also one of the important factors governing slip measurement is calculation and estimation of ground speed and revolutions of the tire, for this one has to go through different methods of speed and revolution measurement and also the equipment employed for doing such work. 1. Optimum wheel slip and traction 1.1 Frank M. Zoz (1972) developed a method of predicting tractor drawbar performance under various field conditions. It was predicted in his studies that the performance of the tractor is highly dependent upon the soil surface because of the tire performance upon that particular surface. The soil and the tire, since both are deformable, a certain amount of slip or travel reduction occurs as pull develops. The primary performance measure used in comparing tire performance is Dynamic Ratio. Dynamic Ratio is the ratio of pull developed by the traction device to the dynamic weight upon the device. Dynamic Ratio is primarily a function of travel reduction or slip of the driven wheels. It magnitude also depends upon the soil surface, and to a lesser extent upon a host of other variables such as tire pressure, configuration and height of lugs, tire size and ply as related to the weights upon the tire and the duals and tandem arrangements. The effects of the soil on the tractive performance were studied. Efficiencies of over 90% may be obtained on a concrete surface while 50% is difficult to obtain in soft or sandy conditions. Dynamic Ratio may vary from over 0.80 at 15% slip on concrete to as low as 0.30 at approximately 30% slip in sand.