THE INFLUENCE OF THE LIFT ANGLE ON THE CENTER OF GRAVITY: MEASUREMENTS FOR ZERO TURNING RADIUS MOWERS

Previous research on the measurement of the center of gravity (CG) positions has focused on theoretical measurement models. Little research has been conducted to investigate the influence of lifting vehicle parts during the tests on the accuracy of these measurements. Because of problems caused by the springs, fuels, hydraulic oil, lubrication oil, and elastic cells and the shifting parts mounted on the mower frame during the CG height measurements, a test method supported by a grant from the National Natural Science Foundation of China was developed to minimize their influence on measurement errors. By using electronic scales and a digital protractor, stable lifting angles were found on the basis of the Mass Reaction Method. The results show that the CG height was relatively constant as the lifting angle (lambda), the angle between the frame and the horizontal plane, of the mower was increased from 12 degrees to 15.0 degrees with one-third of a tank and a full tank as well as an almost dry system. The true value of CG height (Z(cg)) was determined by averaging the measurement values of CG height Z(cg)(lambda)[Z(cg)(lambda) is the measurement value of the CG height corresponding to its lifting angle lambda] in the range of stable lifting angles. Error transfer theory was applied to evaluate the validation of this measurement result. An error analysis of the measurement values shows that increasing the value of the lifting angle appropriately is an effective method for minimizing the CG height measurement errors.