Correct juxtaposition of a tractor with a machine affects time and being on time with a treatment as well as fuel consumption. The article presents analysis of the selection of various cultivation machines to a 14 kN class tractor in the aspect of obtaining maximum performance and minimum fuel consumption. The following cultivation machines were investigated: cultivation aggregates and chisel plows, disc harrows, field ploughs. During exploitation, research measurements of fuel consumption and actual speed of the units operation were taken. It was showed that incorrect selection of the working width of a machine for a tractor results in a decrease of the cultivation unit performance and in many cases in the increase of fuel consumption.