Constant level oilers

Many pumps are equipped with oil-lubricated bearings. The amount of oil
lubrication is usually controlled with glass bottle-type constant level oilers.

How a constant level oiler operates

The lubricating oil stays in the bottle for as long as the oil level in the bearing
housing is level with the mouth of the glass bottle. When the oil level in the
housing drops, air enters the bottle, and oil drops into the housing until the oil
level is inline again with the mouth of the bottle. Hence, the term constant level

The oil bottle is placed on a leveling bar that can be adjusted, up or down, and
locked in place. Raising the leveling bar raises the level of the oil bottle mouth
and, similarly, the oil level in the bearing housing.

The oil setting must be checked at the site. To check the setting, refer to the
instruction sheet that comes with the oiler. Handle the oiler carefully to avoid
contaminating it with dirt or moisture. And always use the manufacturer’s
recommended oil.

As rule-of-thumb, the oil level should cover half of the lowest ball (in a ball
bearing) or ¼” above the bottom of the oil ring (in a journal bearing). Insufficient or
excessive lubrication will have detrimental effect on bearing life.

Related article and topic

Constant level oilers – seven mistakes to avoid when installing, applying, and

R: 0311-COLE
F: constant level oilers

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Photo of typical constant level oilers
Example of commercially-avaiable glass-type constant level oiler
Photo shows examples of commercially-available
glass bottle-type constant level oilers.