小四轮拖拉机,大多配置单缸四行程发动机,在飞轮上设有上止点刻线,水箱并设有上止点指针刻线,只要两刻线相对,则表明此时活塞正处于上止点位置。而根据单缸四行程发动机工作原理可知:曲轴转两周才能完成吸气、压缩、作功和排气四个行程,所以曲轴每转一周都使活塞处于上止点位置一次(即飞轮每转一周时都能使上止点刻线与水箱指针刻线相对一次),其中有一次是压缩行程上止点,另一次就 Small four-wheel tractors, most of the configuration of single-cylinder four-stroke engine, the top of the flywheel is provided with engraved line, the tank and top deadline pointers engraved lines, as long as the two engraved line relative, then the piston is at the top Point location. According to the single-cylinder four-stroke engine operating principle we can see: crankshaft turn two weeks to complete the intake, compression, work and exhaust four trip, so the crankshaft every turn a week in the top dead center piston position (ie flywheel per revolution A week when the top deadline can be engraved with the line pointer relative to the tank pointer), one of which is compression stroke top dead center, another