The text reads "In order to keep the tractor in a good technical state, maintain normal operation, reduce failures, and prolong the service life of the tractor and its parts, we must maintain the tractor in time. The so-called maintenance refers to the systematic inspection, cleaning, lubrication, tightening, adjustment or replacement of some parts of the tractor on a regular basis." (为了使拖拉机经常处于完好的技术状态，保持正常工作，减少故障，延长拖拉机及零件的使用寿命，我们必须对拖拉机进行及时的保养。所谓保养，就是要经常地和定期地对拖拉机各部件进行系统的检查，清洁，润滑，紧固，调整或换某些零件。)

The table at the right refers to the moment when maintenance should take place.