A study was carried out at the Faculdade de Engenharia de Guaratinguetá - FEG-UNESP, SP, in the acoustic and vibration laboratory as well as in an experimental area, to: a) determine the levels of vertical vibration in both the seat and seat base of an agricultural tire tractor under operation (harrowing) at different forward speeds; b) characterize the frequency range presenting the highest vertical vibration peaks in the tractor operator seat; c) analyze ride comfort for tractor operators by comparing the actual level of vibration with that of the main effective norms. The data acquisition system consisted of some vibration sensors, conditioners, amplifiers, and a digital-analogical converter plugged to a microcomputer and connected to the tested tractor. Later, the data were treated by the program ORIGIN 50. Based on the results, it was concluded that the acceleration levels obtained at the upper part of the seat were much lower than those in the seat base at the three operational speeds, whereas the third gear presented the highest vibration levels; the frequency range from 2 to 4 Hz presented the highest peaks of vertical vibration; the values of the total weighted acceleration were found to be much above the limits determined by the norm ISO 2631 for an 8-working hour period; the vibration levels increased as the forward speed of the tractor-implement system increased.
Vibration; sensors; tractor
