小型拖拉机调修最佳周期的试验研究

在许昌县选取了９０台小型拖拉机作为试验对象。先将其进行调修，使其动力性、经济性标准要求，在以后的作业中，每荼２００ｈ对示范车进行了１次功率、耗油率了进行６次根据检测记录，以其多数车辆发动机功率下降至低于正常值的９０％，油耗明显上升的第５次为分界线，从而确定出小型拖拉机调修的最佳周期为８００ｈ，试验还表明，气门间隙、喷油压力的变化是影响小型拖拉机功率下降，耗油率上升的主要因素。

Study on the Best Period of Adjusting and Repair for Small Tractors

Ninety small tractors are taken as an object of study in Xuchang County.First of all,these tractors are adjusted and reparied so that the power and economic performance of the tractors can compare with those of the standard ones. Then the engine output and consumpation of the fuel are tested 6 times, once after working for 200 hours. The best period of adjusting and repair determined by the test result is 800 hours,at which the engine output of the tractors is greatly reduced while the consumpation of fuel is sharply increased.The test result also shows that the valve clearance and the change of injection pressure are the major factors affecting the reduction of power and incresae of the consumpation of the fuel for the tractors in use.