A drip oiler is a small reservoir with an adjustable needle valve that lets oil fall onto the bearing at a set rate, and a wick oiler is a felt or cotton wick that draws oil from a reservoir by capillary action; both feed continuously from gravity and suit unattended running. Set a drip oiler’s rate by counting drops against a known volume, and expect to refill either one about once a day.
Part of Bearings and Bushings
Gravity-fed and capillary-fed oilers that keep a bearing supplied without anyone standing at the machine.
A Feed That Runs While Nobody Is Watching Still Needs A Rate
A grease cup or oil hole is only as good as the person’s memory. The two continuous types in the carrier article remove that dependence. The drip oiler holds oil in a small reservoir with an adjustable needle valve; the wick oiler uses a felt or cotton wick to draw oil from the reservoir by capillary action, and the carrier calls it self-regulating because it draws more oil when the bearing runs hot. Plain Bearings describes the Stauffer-style wick cup, whose reservoir holds about a day’s worth of oil, as ideal for unattended operation.
Oil is meant to flow, so the lubricant has to be one that does. Tallow is semi-solid at room temperature and will not drip until it is warm; castor oil and mineral oil are liquid at room temperature (Lubricant Types).
What You Need
- A reservoir above the bearing and a drilled oil hole leading to its groove
- A needle valve for a drip oiler, or a felt or cotton wick
- A liquid lubricant whose temperature limit exceeds the bearing’s working temperature
- A measuring spoon or small cylinder to calibrate against
Method: Set Up And Calibrate
Step 1: Mount the reservoir above the bearing, so gravity does the work, with the outlet over the oil hole.
Step 2: Start with the valve nearly closed and open it until drops fall at a steady rate.
Step 3: Calibrate. Count drops into a measuring spoon. Whatever number of drops fill 1 mL on your oil, that is your conversion for this oiler and this oil.
Step 4: Choose the feed rate by looking at the bearing: a film of oil at the exit is right, a pool on the floor is too much, and a dry bearing end is too little.
Step 5: For a wick, trim it to length and make sure its end touches the shaft or the groove. A dirty or dried wick feeds nothing.
Step 6: Refill every day, and write the refill on the schedule (Lubrication and Failures).
Worked Example
Suppose counting shows 20 drops fill 1 mL of your oil (an assumed result of the calibration, not a general figure), and the valve is set to 6 drops a minute. Over an 8-hour shift of 480 minutes that is 6 x 480 = 2,880 drops, and 2,880 / 20 = 144 mL. A reservoir that holds 150 mL therefore lasts one shift at that setting, and a half-day’s reservoir is the wrong size.
Doubling the setting to 12 drops a minute empties it in half the time. The calibration gives you the rate, and the bearing tells you whether it is enough.
Common Mistakes
- Leaving the valve open at a long stop. The reservoir drains on the floor; close it or lift the wick out when the machine is stopped for long.
- Letting dirt into the reservoir. Strain oil through cloth before filling.
- Using tallow in a drip oiler. It does not flow when cold, then runs out freely when warm.
- Mounting the drip over a belt. Oil on a belt makes it slip.
Safety
Oil on belts and on floors
Oil on a belt or pulley makes the belt slip and can throw it; oil on a floor can make the person refilling the oiler slip toward the machine. Place the drip clear of belts, wipe spills, refill with the machine stopped, and know where the stop is and how long the shaft takes to coast down.
What’s Next
- Learn next: Fitting and Alignment - installing the bearing the oil feeds
- Combine with: Grease Cups and Oil Holes - the hand-fed alternative