Measurement of Static Lateral Stability Angle and Roll Moment of Inertia for Agricultural Tractor with AttachedImplement

摘要

Many fatalities result from rollover of agricultural tractors in Japan each year. Beside the equipment of ROPS and seat belt, warning device, which early alerts operator of impending rollover based on tractor stability index, is a countermeasure to prevent fatal accidents. The stability index requires inertial parameters to calculate a warning threshold. In this paper, measurements of center of gravity and lateral stability angles of three agricultural tractors were made and lateral stability angleswere also calculated and compared with measured values of the tractors and tractor-rotary tiller combinations. Measurement of roll moment of inertia for two tractors and two rotary tillers were also conducted and roll moments of inertia for tractor-rotary tiller combinations were calculated. The measurement and calculation results show that attached implement increased the lateral stability angle of tractors in phase I rollover and decreased the angle in phase II rollover and for a certain combination of tractor-rotary tiller, there was no transition from phase I to phase II rollover. The difference between the measured and calculated lateral stability angle in phase I rollover ranged from -3.5 to 2.5 degree, while that in phase II rollover was from 0.2 to 5.2 degree. The moment of inertia about the longitudinal axis through the center of gravity was 203 and 433kgm2 for tractor A and B, respectively, while that was 52 and 94kgm2for rotary tillers D and F, respectively. Values of calculated roll momentof inertia were 265 and 540kgm2 for tractor A-tiller D and tractor B-tiller E, respectively.