In seeking greater efficiency and profit in farming, it is important to use the available capacity in power-driven machinery as fully as possible. In this investigation using a simulated central Swartland farm, the profitability was increased by eliminating under-utilised power-driven machinery, resulting in a reduction in mechanisation expenses. The change arising from this in the mechanised system has a further effect on the existing farming system in that wheat production, the most important branch, undergoes a structural change. Cost savings (working capital and interest) and the increased income from the expansion of the stock factor compensate for the loss of income caused by sowing less. The determining factor influencing profitability is, however, the saving in mechanisation expenses, which represent a fixed cost component.