Tractor´s steering stability analysis after towing trailer based on handling diagram

Tractor´s centroid moves backward and axle load reallocates after towing a trailer which made the automobile´s steering stability changes. The paper derived steering stability formula of multi-axis tractor, analyzed tractor´s steering stability trends with the change of saddle´s previa distance, trailer´s loadage and lateral acceleration using handling diagram. Conclusions are got using MATLAB simulation: saddle´s backward motion made tractor´s steering stability worse; at fixed loadage, tractor´s steering stability gets better with the increase of lateral acceleration; at low lateral acceleration, with the increase of trailer´s loadage tractor´s stability apt to over-steer while at large lateral acceleration tractor´s stability has serious under-steer trends with the increase of loadage.