A constant-level oiler is used to check the lubricant quantity (e. g. in rolling element bearings). As long as the reservoir contains oil, the oil level in the bearing housing is sufficient to ensure reliable lubrication.
Description
Specification
Wick feed lubrication is a well known means for feeding small amounts of oil lubricant from a reservoir to the ball pathways, which can then be continually recirculated to the reservoir.