Sawmill drawbar lifting cylinder has a small hole is for what?

The sawmill drawbar, belonging to a mechanical reciprocating mechanism, above to lubricate many joints, pay attention to the oil lubrication; specific structure of various sawmills are not the same, it should be an overflow hole, do not lubricate other parts of the body, you can install a small tube, diverted to the oil tank, so that it returns to the oil tank. I hope you are helpful.