Choosing Wheelslip and Workrate to Minimise the Cost of Tillage

Four models of tractor performance have been combined to investigate the variation of the total costs of tillage with the operating speed or workrate. These models are for tillage draft force, the tractive elements, the engine performance and operating costs. Variation of the model parameters within practical limits has shown that total costs per hectare reduce consistently with workrate, and that there is a range of optimum slip which minimises costs at any given speed.