The instrumental system consisted of the following sensors. A digital encoder mounted on the axis of a rear wheel of the tractor for the measurements of speed and slip. Two mono-axial load cell, with full scale of 98 kN (plough, subsoiler and combined cultivator tests) and 49 kN (rotary and disk harrow tests), lodged in a suitable draw bar. The load cells directly measure the force of traction generated when the tractor-implement system, with gearbox in neutral, is pulled by a dynamometric vehicle.