Pressure limiting valve is fixed in oil pump house, it has steel ball type or plunger type. When the oil pressure in outlet is up to a certain height, the steel ball will be pushed away by the pressure affect on ball surmount the spring thrust of pressure limiting valve.
And some lubricating oil through oil tube return oil pan.
Pressure limiting valve limits pressure of oil passage in order to avoid the pipe and filter burst.
At the same time, it prevents excessive oil to enter into combustion chamber and increase oil consumption, which affect engine performance.