Design Of Performance Test Bench For Tractor Power Take-off

An important part of agricultural modernization is the modernization of agricultural machinery.The power source of most agricultural machinery is tractors.The improvement of tractors’ performance and functionalization has a major impact on the modernization of agricultural machinery and directly affects the development of agricultural modernization.With the development of agricultural machinery,more and more tractor supported agricultural machinery requires tractors to provide power,so the tractor power take-off(PTO)shaft configuration is becoming more and more common.By testing the tractor PTO shaft,we are able to obtain important performance index data such as the power,economy and working stability of the tractor under the whole machine state.The improvement of tractor technology requires improvement of the category and measurement accuracy of items reflecting their technical indicators and also requires improvement of the performance test equipment for tractor PTO shaft.There are many types of related test equipment available,each with its own features.However,as a whole,there are certain deficiencies in structure,test and control accuracy,ease of operation,and software functions.If the torque is not well matched,the power margin could be too large which causes high cost.Some are limited by the cooling capacity and can only be used for testing of low power tractors.Some adopt power grid regenerative absorption energy with high precision and stable control,but the control system is complex and expensive,which is difficult for general enterprises to afford.Some pedestals do not have a lifting function,which is difficult to navigate and time-consuming.Some are missing fuel temperature control devices,which affect the measurement accuracy.In view of the above problems,this paper summarizes the functions,structure,test and control principle,evaluation criteria and operation mode of other tractor PTO shaft test rigs,and designs a new type of test rig.Firstly,the current standards and enterprise requirements were analyzed,the parameters of the test bed test and control system were determined,and the overall design of the test bench was completed.Compared to a variety of options,the design optimized the test bench lift system.The influence of the deflection angle of the transmission shaft on the tranission torque and the rotational speed was analyzed.By analyzing the characteristics of various dynamometers,the DC power dynamometer was selected as the test bed loading host,and the braking torque was controlled by the programmable power supply to adjust the excitation.Secondly,the energy was absorbed by the resistor energy consumption,and the cooling water system was eliminated by using air cooling.In order to improve the test accuracy,the fuel consumption meter was designed and optimized,and the software algorithm was used to improve the measurement accuracy after the actual test.A fuel thermostat system with oil return processing function was designed to meet the requirements of National Ⅲ engine testing.Finally,using the Viusal C++ software platform,the PC software was developed,which can be remotely controlled,automatically adjusted,and tested.It can process,store test data and draw characteristic curves,and print test reports.After the test bench was designed and manufactured,the actual test was carried out to verify the preset functions of the test bench,which can meet the requirements of the performance test of the tractor PTO shaft.The various systems of the test bench are stable in operation,easy to operate,high in automation,with improved test efficiency,reduced labor intensity,and good prospects for popularization and application.This test bench not only can test the performance of the tractor PTO,but also can be used as a working condition control platform to simulate various working conditions of the tractor,to match the other parts of the tractor,and to comprehensively evaluate the influence of other external factors on the whole machine.It has great practical significance for the design and development and performance improvement of medium and large tractors.