由于联合收割机的滚筒转速直接影响到脱粒的效果．因此，就要通过转速表来时刻监视滚筒的转速，以达到良好的工作状态。一旦转速表损坏就无法了解滚筒的转速，这时往往需要更换一个新表。而收割机在野外作业时，有时往往一下子买不回来而影响工作，笔者有一个既节约时间又降低 As the combine harvester drum speed directly affects the threshing effect. Therefore, it is necessary through the tachometer to monitor the drum speed, in order to achieve a good working condition. Once the tachometer damage can not understand the drum speed, then often need to replace a new table. The harvester work in the field, sometimes one often buy can not come back and affect the work, I have a time and reduce both