东方红－ 75型拖拉机使用时间长了，发动机会发生气门半圆锁瓣自动脱落的故障。对此，若机手处理不当或不及时，往往会使气门落入气缸，导致活塞被顶烂，连杆变形等严重故障的发生。因此，在安装、使用气门锁瓣中应注意以下事项。 　　（ 1）安装半圆锁瓣以后，将气缸盖平面向 Dongfanghong - 75-type tractor long time, the engine valve will occur semi-circular valve automatically fall off the fault. In this regard, if the hands of improper or improper handling, often will make the valve into the cylinder, leading to the piston was the top bad, connecting rod deformation and other serious failures. Therefore, in the installation, the use of valve lock valve should note the following. (1) After installing the semi-circular locking flap, align the cylinder head flatly