LOADS IN TRACTOR LINKAGES WHEN TRANSPORTING REAR-MOUNTED IMPLEMENTS - DEVELOPMENT OF MODELING AND MEASUREMENT TECHNIQUES

Loads induced in transport can be the highest to which an implement frame or tractor linkage is subjected. Methods of predicting them would allow equipment designers to estimate the loads new machines are likely to encounter, thus assisting in their design. Further analysis would allow more effective use of material. Such methods would also help in formulating endurance test procedures under laboratory conditions. A computer model of a tractor and implement has been developed to predict time histories of the loads at the implement attachment points and also the tractor and implement accelerations. The input may be any vertical displacement time history at one or all of the tractor wheels. The equations of motion were derived using the method of Lagrange and allow a non-linear description of the tyres but assume a rigid connection between the tractor and implement. Using measured tyre dynamic properties, results from this model have been compared with those obtained experimentally on a purpose-built rig. Some agreement was found between the measured and predicted frequency responses of linkage loads and tractor and implement accelerations. However, there was free play in the three-point linkage and it is concluded that this was of such importance that it and the stiffness of the linkage should be included in future models. © 1991 The British Society for Research in Agricultural Engineering.