What does the oil seal mean? what's the effect?

Update:07-07-2022
Summary:
The meaning of oil seal is: oil seal is a mechanical component used to seal oil (oil is the most common liquid substance in the transmission system, and also generally refers to the general liquid substance), which isolates the parts that need to be lubricated in the transmission parts from the output parts, Do not allow the oil to leak.
Its functions are as follows:
1. Prevent oil from leaking through the rubber oil seal cover and oil seal washer;
2. Restore the elasticity of the rubber oil seal and protect the elasticity of the oil seal and O-ring.
3. Prevent oil from being sucked into the combustion chamber, prevent and reduce smoke exhaust.
4. Reduce engine noise and improve engine compression ratio.
5. Extend the service life of the engine and prevent expensive maintenance costs.
6. Effectively suppress the oil leakage of the steering gear.