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What are the best practices for oil lubricating your industrial equipment?

A total loss application, a self-contained application, or a circulating application are the three types of oil applications. The term “total loss” or “once-through oiling” refers to the fact that the oil only passes through the bearing once and is then lost for future use. Because the oil is only used once, it is also known as “All Loss” oiling. Hand oiling, drop feed oiling, wick-feed oiling, and bottle oiling are examples of this type of method.

Hand Oiling: 

Hand oiling is the direct application of oil to a moving machine part from a hand oil can. An excessive amount of oil is applied, which quickly evaporates, leaving the bearing to operate with insufficient oil until the next oiling. As a result, bearings lubricated by hand are not as well protected against wear as those lubricated by more reliable oiling methods.

Drop feed:

Drop feed oilers typically include a glass or plastic reservoir, a needle valve for adjusting the feed rate, a snap level shut-off, and a sight glass for observing the feed rate. They are typically used on lightly loaded horizontal bearings that require a slow oil supply.

A drop feed oiler that is electrically controlled can be outfitted with a large capacity reservoir and a manifold that provides individually adjustable drop feeds for several bearings. Lubricant is delivered to various bearings via tubing lines. A solenoid is a valve that controls the flow of oil from the reservoir to the feed control manifold by opening and closing when the machine motor is started or stopped.

Wick Oilers:

Wick Oilers use a wick made of loose-textured, long-fiber wool to supply oil to the bearing via capillary action. The rate of feed can be controlled by changing the wick size or adjusting the oil level in relation to the feed end of the wick. Raising the wick will halt the flow of oil. The underfeed oiler is made of metal and has a shank that threads into a hole in the bearing housing. Through the hole in the underside of the bearing sleeve, oil is fed up the wick to the shaft.

Wick oilers are used on horizontal bearings that operate in dusty environments. The wick acts as a filter, preventing contaminants from entering the bearing. When the wick gets clogged with dust, it needs to be cleaned or replaced. When the wick end of the rotating shaft becomes glazed, it should be trimmed off to provide a fresh surface. These are frequently used in railroad traction motor bearings.

The bottle oiler:

The bottle oiler is made up of an inverted glass bottle that is mounted above the bearing and is equipped with a sliding pin that rests on the journal. The pin vibrates as the journal rotates. The vibration causes oil to flow from the bottle to the bearing via the space between the pin and its sleeve.

Consider the following when using the oil cup method:

  • Typically used to transport large amounts of oil (large trunnion bearings)
  • Speed is restricted.
  • To function, the shaft must be rotated.
  • There is some lag in the quantity transfer.
  • Work whenever the shaft rotates

The bottle oiler is made up of an inverted glass bottle that is mounted above the bearing and is equipped with a sliding pin that rests on the journal. The pin vibrates as the journal rotates. The vibration causes oil to flow from the bottle to the bearing via the space between the pin and its sleeve.

Consider the following when using the oil cup method:

  • Typically used to transport large amounts of oil (large trunnion bearings)
  • Speed is restricted.
  • To function, the shaft must be rotated.
  • There is some lag in the quantity transfer.

Work whenever the shaft rotates

The constant level oiler is an inverted glass or plastic bottle with a neck that extends into the oil in the bearing reservoir’s overflow cup. When the oil level in the bearing reservoir falls below the end of the bottleneck, a vent allows air into the bottle. Lubricant flows from the bottle to the overflow cup, then into the bearing reservoir. When the proper oil level is restored, oil covers the bottleneck and prevents any additional air from entering the bottle. As a result, the bearing reservoir maintains a constant level. This provides the benefit of an additional reservoir.

In the ring oiling method, a metallic disc or ring larger in diameter than the journal rides on it and turns as it rotates. The ring absorbs the oil and transports it to the top of the journal, where it flows along and around the journal, providing lubrication before returning to the reservoir.

Chain oiling is similar to ring oiling, but instead of the ring, a small-linked chain is used. The chain will transport more oil than the ring. An oil ring or collar can be used to transport oil from the reservoir to journals that are turning at such high speeds that rings and chains would slip. As the journal rotates, the collar, which is attached to the journal, dips into the oil reservoir, carrying the oil to an overhead scraper, which removes and distributes it along the journal.

Most internal combustion engines and many gears use splash lubrication. The moving parts are immersed in oil and lubricant is sprayed on other components.

Mechanical lubricators are made up of an oil reservoir, one or more pumps (usually plunger type), powered by a rotary or ratchet mechanical drive or an electric motor, feed rate adjustment for oil delivery, usually a sight feed for checking lubricant delivery, and an oil strainer at each pump’s intake.

A stream of compressed air is used to break up the oil into a fine mist in oil mist lubrication. A fine dry fog of oil is conveyed from the generator to the bearings via tubing lines. On impact, the oil particles are reclassified and converted to a wet fog at the point of application. The droplets will recombine due to the turbulence. To prevent contaminants from being transferred to the lubricated equipment, distribution lines are connected to the top of the main line. Only trace amounts of oil are consumed

The flow of air keeps dirt out of the bearings and cools them. High-speed bearings are particularly well-cooled by oil mist. In comparison to other lubrication systems, oil mist has the following advantages:

  • A steady supply of new lubricant
  • Slight pressurisation aids in contamination reduction.
  • There are no moving parts or cyclic mechanisms in the system.
  • Flow rate and oil level are monitored by alarm systems.
  • Lubricant costs are reduced when lubricant consumption is low.
  • Reduces bearing housing temperature by up to 30%. However, the benefits may be outweighed by the following drawbacks:
  • High initial investment
  • Flow rates are difficult to set and maintain.
  • If stray mist is not contained, there may be some environmental and/or health concerns.
  • Extremely sensitive to temperature fluctuations
  • Return lines must collect mist that has not been reclassified as liquid.
  • If the oil overheats, varnish and sludge may form.

Spray lubrication for oil is used on mills to lubricate plain roll neck bearings. A spray gun, similar to those used for painting, uses compressed air to coat gear teeth with a thin layer of grease to provide lubrication.

Circulating systems keep bearings lubricated at all times. Oil can be strained, filtered, and cooled because it is constantly re-used. A relief valve or orifice sizing regulates oil pressure. A pump is used to metre the lubricant in a direct circulating system. The pump creates pressure in an indirect system, and metering valves in supply lines metre the amount of lubricant. Gravity systems are fed by two reservoirs: one above the highest bearing to be lubricated and one below the lowest bearing.

The oil drains from the upper reservoir, lubricates the bearings by gravity, drains to the lower reservoir, and is returned to the upper reservoir via a pump. A pump is used in pressure feed systems to force oil to bearings, where it drains to a reservoir by gravity. On the return lines, cooling may be used. This type of system is useful when dealing with large amounts of oil.

Reservoirs should allow oil to settle for a long enough period of time to separate air, water, and solid impurities. Depending on the system, fluid residence time can range from 3 to 60 minutes. Low oil depth allows entrained air to escape more quickly and water and solids to settle more quickly. To provide the longest possible oil path, a long tank positions the pump suction further away from the oil inlet. These factors result in the typical reservoir proportions listed below: In all methods of reservoir lubrication, it is critical to check the reservoir on a regular basis to ensure that the proper oil level is maintained. For this purpose, a level gauge is installed in the reservoir’s lower section.

Moisture and vapour can escape through vents. Filters and desiccant breathers keep dust and moisture out of the oil. A vapour extractor pump is frequently used to vent large oil systems. A vent above the maximum oil level, in addition to the vent above the maximum oil level, should be provided for tank inspection and cleaning. Oil reservoirs require headspace to allow for thermal expansion, turbulence, foaming and air release, and system fluctuations.

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