Design And Application Of Front Drive Axle For Heavy Tractor

The front drive axle is one of the key components of the tractor.Its function is to connect the tractor body and the front wheel.It bears the weight of the front of the tractor and allows the front wheel to deflect relative to the body to realize the steering of the tractor.The performance of the front axle has an important i MPact on the tractor’s traction characteristics,reliability and driving comfort and other key performance.The front drive axle of domestic high end heavy-duty tractors is mainly imported,which is one of the bottlenecks of domestic tractor production at present.Based on the design process of the front drive axle and its application in L-series heavy-duty tractors of a domestic enterprise that the author is responsible for,this paper has carried out research work on the overall design calculation and performance analysis of the front drive axle,system matching and optimization,and the application and verification of the whole machine.The main research contents are as follows:(1)This paper analyzes the technical development of tractor front drive axle and the research status at home and abroad.Aimed to meet the design requirement for L-series heavy-duty wheeled tractors,the determination method of tractor’s transmission ratio,bearing capacity and steering radius is analyzed from the perspective of load bearing under actual working conditions.Through the calculation and analysis of tractor front drive axle parameters,improvements are made to the design process and method of tractor front drive axle.Finally,the basic parameters of the front drive axle are determined.(2)According to the load-bearing requirements and system composition of the whole machine,the gear transmission structure of the front drive axle composed of the central main reduction gear,differential gear and end planetary transmission reduction gear is designed,and the transmission ratio is determined through calculation to meet the working requirements of the whole machine;In order to improve the reliability,the life calculation and type selection of the bearing are completed under the extreme working conditions(maximum load and maximum working speed).After calculation,the selected bearing can meet the lifetime requirement of 8000 h;The scheme design,parameter determination and strength check of the gear transmission structure are carried out.The stress calculation and gear modification of the solar gear system are carried out by using ANSYS software,which significantly improves the gear strength,reduces the meshing heat,and ensures the reliability of the front drive axle.(3)Through the systematic design of the front drive axle and the optimization of the shell,the design strength of the driving axle is able to meet the load-bearing requirements.Then the modeling and simulation of each module are carried out by using ANSYS to analyze the stress characteristics.On this basis,the simulation model of the whole system is established,and the life and strength coefficients of the system bearings,shafts,gears,etc.are analyzed to ensure that the core components of the front driving axle meet the load-bearing requirements of the whole machine.(4)Based on finite element theory and methods,a multi-rigid body model of the system is established for the tractor front drive axle housing to calculate the stress and deformation of each part of the axle housing,so as to optimize the shell structure parameters.After optimization,the safety factors of two high-stressed regions has been increased by 23.7% and 26.9% separately,meeting the design requirements;In order to avoid resonance when the tractor is running,the modal calculation and analysis of the front drive axle shell are carried out.The results show that the resonance range of the engine is 88-132 Hz,and the resonance range of the road excitation is 1-21 Hz.While the minimum natural frequency of the front axle shell is 194.09 Hz,higher than these ranges,so it could be ensured that the front axle housing structure will not resonate.(5)The designed front driving axle elements are used in bench verification and application of the whole machine.The bench test results show that the prototype meets the requirements of loading test,tractor hub test,reliability test and so on;The reliability of the L-Series heavy-duty tractor has been verified for 2000 hours under typical working conditions such as plowing,shoveling and land preparation.The application of the whole machine shows that the product performance is reliable and trouble free,the gears and bearings are worn normally,and there are no signs of pitting corrosion and burn.The whole tractor product has finally obtained the agricultural machinery test and appraisal certificate,and has been put into application.The front drive axle of heavy-duty tractor designed in this thesis has solved the problems of poor reliability,high failure rate and short service life of the front drive axle of domestic heavy-duty tractor,and formed the independent research and development and production supporting capacity.This is of great significance to change the current situation that the front drive axle of domestic heavy-duty tractors depends on imports and to improve the level of domestic self-development.