| Since the"Thirteenth Five-Year Plan",the level of agricultural mechanization in hilly and mountainous areas has been continuously improved.As the most important agricultural power machinery,the demand for hilly tractors has continued to increase.At present,most of the research on attitude-adjusted hilly tractors is in the stage of theoretical analysis and research.The main purpose is to achieve the body leveling function.The tractor can achieve height difference leveling in a static state.However,because the tractor body is rigidly connected,when passing through obstacles,the tires have insufficient grip,and the danger of slippage and overturning is easy to occur during the operation.Such tractors cannot be well adapted to the working environment of hills and mountains.Aiming at the problems that the current attitude-adjusted hilly tractors can only achieve static leveling,differential height leveling,and low leveling accuracy,a twisting and swing posture attitude adjustment device of the twisting and swinging wheel hilly tractor was designed.The reliability of the device and the superiority of the attitude-adjusted tractor are verified through theoretical analysis,simulation and field experiments,which provide a reference for the research on hilly tractors and the future development of agricultural mechanization in hilly and mountainous areas.The main research contents are as follows:（1）The twisting and swinging attitude adjustment device of the hilly tractor was designed.The motion state of the tractor on the transverse and longitudinal slopes was studied,and the factors affecting the stability of the tractor’s operation on the slope were obtained.The requirements for the tractor’s attitude adjustment were put forward,which provided theoretical support for the design of the attitude adjustment device.The attitude adjustment device and hydraulic control system were designed,and the whole structure of the hilly tractor and the working principle of the twisting attitude adjustment device were described.（2）The structure optimization design of the twisting and swing attitude adjustment device was carried out.The statics simulation of the roll frame,the key component of the attitude adjustment device,was carried out.According to the analysis results,in order to meet the lightweight design goal,a multi-objective optimization design based on the response surface method was carried out without changing the structure.The quality of the final optimization result was reduced by 4.51%;the modal analysis of the optimized roller frame was carried out to ensure that the roller rack will not have resonance.（3）The multi-working condition simulation of the wheel hilly tractor was carried out.The working process of the twisting and swing attitude adjustment device was simulated,and the maximum rotation angle of the attitude adjustment device was 15.2°;the stability of the tractor was simulated on the slope ground,and the maximum inclination angles of the tractor transverse and longitudinal slope to maintain stability are 19.8°and 23.2°respectively;By analyzing the movement of the tractor under different working conditions,it was obtained that the hilly tractor can adapt to different road conditions.（4）The field adaptability test of the twisting and swing posture wheeled tractor in hilly and mountainous areas was carried out.The average unit operation fuel consumption and average productivity were used as the evaluation indicators,the influence of the two factors of the operation slope angle and the operation depth on the performance of the tractor was explored,and according to the results of the orthogonal test,the optimal working parameters of the tractor were determined:horizontal rotary farming（12.3°,10cm）average fuel consumption per unit operation was 11.35kg/hm~2,the average productivity was 0.72hm~2/h,and the average unit operation fuel consumption of horizontal plow farming（10.6°,31cm）average fuel consumption per unit operation was 21.43kg/hm~2,and the average productivity was 0.62hm~2/h. |
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