The reduction of torsional vibration in a rotary cultivator transmission by means of resilient coupling

Abstract Torque fluctuations recorded at the power take-off shaft of a rotary cultivator suggested that under certain conditions, the transmission was being excited into resonance. The work described was initiated in order to determine if these high amplitude vibrations could be reduced by lowering the stiffness of the transmission. To reduce the stiffness, a rubber-element resilient coupling was fitted between the final drive sprocket and the rotor shaft, while the overload slip clutch was temporarily locked up. Tests were carried out on a variety of land conditions and comparison tests were also carried out with the transmission as normal. Analysis of the results showed that when the resilient coupling was used, the mean value of torque peaks reached was considerably reduced. Isolated high peak torques were still produced but there was much less tendency for torque reversals to occur. The overall effect of the resilient member is therefore considered to be beneficial in increasing the fatique life of the transmission components, if not entirely eliminating the need for an overload slip clutch. With the reduced transmission stiffness, however, the requirements of any overload protection device become much less demanding.