The power demand of the demolition of pineapple (Ananas comosus) fields, whose production cycle is finished with a flail mower with two different knives, a cutting apparatus with three angular velocities, and a tractor with three translation velocities, was determined using strain gage measures. The results of the investigations demónstrate the influence of the knife type and cinematic regime of the cutting apparatus in the demand of energy in the pineapple demolition. Furthermore, they permitted the validation of models of the power demand of the flail mower.