The power demand for the demolition of pineapple (Ananas comosus) fi elds at the end of their productive cycle with a fl ail mower has been determined using strain gage measures, the trials were conducted at three different angular velocities of the cutting apparatus and three translation velocities, using two different sets of knives. The results of the investigation show the infl uence of the knife type and cinematic regime of the cutting apparatus in the energy demand; furthermore they allow the validation of fl ail mower power demand models.