4.5.8.e Valve spring
The valve spring keeps the valve closed. It ensuring a tight fit in the valve seat, and also creates a constant pressure of the push rod against the surface of the camshaft cam. The spring is put on the end of the valve rod, which comes out of the sleeve and fixed on it in a compressed state using a plate with conical split “crackers” that enter the groove on the valve rod. Sometimes two springs are installed on the valve: a spring of a smaller diameter - inside a spring of a larger diameter. This is done in order to avoid resonance of the spring at certain engine operating frequencies, as well as to provide a backup in case of a spring break. Springs with variable pitch are often used. This eliminates the likelihood of vibration of the spring and its breakage at a high speed of the engine crankshaft. In case of installing two springs, they are selected in such a way, that the direction of winding their coils is in different directions, which also eliminates the danger of the occurrence of resonant vibrations of springs.
Rubber valve oil seals are installed on the top of the bushings in order to limit the amount of oil entering the guide bushing and eliminate its suction into the cylinder through the gaps in the bushing.
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