Design And Research Of Adaptive Hill-country Tractor Chassis

Is hilly mountainous country and mountain terrain is complex,has specialized in hilly area of tractor chassis relative lack,and ordinary tractor in hilly mountain homework underpowered and easy to turn,turning radius is big,low work efficiency,it is difficult to adapt to the complex working environment in the hilly region and can’t satisfy the operation demand of hilly mountain.Therefore,it is of great significance to develop a kind of tractor chassis with strong adaptability and high stability.This paper analyzes and compares the advantages of the mechanism design of hilly and mountain tractor chassis at home and abroad,and designs a power chassis with adaptive leveling and multi-functional operation.The main conclusions are as follows:(1)According to the landform characteristics of hills and mountains,determine the overall technical scheme and main technical parameters of hilly and mountain tractor chassis,the chassis supporting power is58.8KW(80 horsepower),the chassis wheelbase is 1800 mm,the wheel base is 1296 mm,the lowest ground clearance is 312 mm.The transmission system adopts mechanical transmission,the walking system is fourwheel drive,the steering system can realize four-wheel out of phase steering with full hydraulic pressure,and the chassis can realize adaptive leveling to ensure that the chassis can efficiently complete field operations.(2)Design of chassis transmission and walking system.Chassis gearbox selection and design,the selected gearbox has three forward gear,a reverse gear.The forward gear ratio is 3.747,9.403,22.644,respectively,and the backward gear ratio is 10.563.The design of fast and slow transmission,the selection of gearbox gear less,can not meet the needs of hilly and mountainous operations,so in the transmission system to add fast and slow transmission,the transmission ratio of fast and slow transmission is 2:1.The design of bevel gear power commutation box,according to the power transmission and chassis leveling needs,the design of bevel gear power commutation box between the front and rear drive axle,the transmission ratio of power commutation box is 1:1.Selection of front and rear steering drive axle,the selected front and rear steering drive axle is the same model,the front and rear drive axle is arranged symmetrically,the total transmission ratio is 12.6.The lowest theoretical speed of chassis is 0.91Km/h,and the highest theoretical speed is 10.89 Km/h.Combined with the overall design requirements of adaptive hilly tractor chassis and the lowest ground clearance consideration,the type of tire chassis is 6.00-16 ordinary cross section drive tire,its cross section width of 165 mm,external diameter of 745 mm,load capacity of 495 Kg.The tire has strong grip and high bearing capacity,and can adapt to the complex road surface in hilly areas.(3)Design of chassis steering and braking system.Two steering modes,front-wheel deflection and fourwheel deflection,are adopted.The minimum theoretical radius of front-wheel deflection is 2003 mm,and that of four-wheel deflection is 1494 mm.The chassis adopts belt braking,which is accomplished by the friction torque between the belt and the brake drum.(4)Design of chassis leveling system.The chassis adopts three-point articulated structure leveling mode,and the articulated devices are respectively arranged on the front and rear steering drive axle differential housing and the inside of the front steering drive axle.The hinged swing support seat on the front and rear bridge differential housing is fixed with the front and rear ends of the frame by bolts.The hinged point on the inside of the front bridge is connected with the hinged point on the side of the frame by hydraulic cylinder.The leveling of the chassis body is completed by controlling the expansion of the piston of the hydraulic cylinder before and after,and the leveling range of the chassis is determined to be in the range of-25°～25°.Using Simulink to establish the kinematic simulation of the leveling mechanism,through the simulation results to determine the leveling cylinder Angle range of 63.9°～107.5°,angular velocity range of-0.2061 ～-0.1535 rad /s,angular acceleration range of 0.0358 ～-0.0035 rad /s~2.Meet the requirements of the job.(5)The performance analysis of the chassis,the theoretical analysis of the vertical and horizontal stability and obstacle crossing performance of the chassis,and the conclusion is drawn: The chassis of the adaptive hilly and mountain tractor is 55.38° and 44.03° uphill and downhill,and the longitudinal slip angles of uphill and downhill are 26.62° and 13.18° respectively.The maximum lateral inclination Angle is 40.01°.Due to the limitation of the maximum flat Angle,the maximum lateral inclination Angle cannot be reached,and the lateral ultimate slip Angle is 26°.The driving wheel obstacle height is 264.5mm,which can meet the requirements of hilly and mountain operations.(6)The design of chassis frame and statics analysis of frame and front steering bridge.ANSYS Workbench software was used to conduct finite element analysis on the forces of the frame and the front steering drive axle under static working conditions.The analysis results showed that: The maximum stress of the frame is 98.12 MPa,the maximum displacement is 0.23 mm,the maximum stress of the front steering drive axle is 31.179 MPa,the maximum displacement is 0.07066 mm,the strength and stiffness meet the design requirements.According to the analysis of the research conclusion,the structural design of the chassis conforms to the actual operation requirements in hilly and mountain areas,and meets the various operating conditions of hilly and mountain areas,which is of great significance to the improvement of agricultural mechanization operation level in hilly and mountain areas.