From the Lubrication Excellence/Reliability World 2005 Conference Proceedings. An excerpt from the paper "How to Inspect and Analyze New Oil Deliveries".

Prior to oil deliveries, an important step to receiving quality oil deliveries is to build a relationship with your oil supplier. Visit the location and tour the facility. Most quality suppliers should welcome the opportunity for you to tour their facility. Ask questions and take note of the following:

* Is there a loading procedure in place to prevent product cross contamination between batch reservoir and tanker?

* Is there a procedure in place for flushing or cleaning tankers/hoses between product deliveries? A tanker load of detergent motor oil delivered prior to turbine oil delivery could cause a problem if not flushed thoroughly between shipments.

* Is the facility clean and organized?

* Can new oil deliveries be filtered? Most suppliers today offer particulate filtration services from the tanker to assure the oil off-loaded from the tanker to your reservoir is clean.

* Can on-site oil analysis be provided with product delivery? Many suppliers today provide on-site particle counting while the product is being off-loaded. This reliable method verifies the cleanliness of the oil going into your reservoir and whether or not it meets the minimum equipment OEM specifications for cleanliness.

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"All of the formal training I've had on the application of lubricants suggests that for greasable bearings, one should never pump in so much grease as to push out the external seals.

However, the instruction manual that comes with Dodge Type-E bearings states: "Operation in presence of dust, water or corrosive vapors - Under these conditions the bearing should contain as much grease as speed will permit, because a full bearing with consequent slight leakage is the best protection against entrance of foreign material."

Won't this ruin the seal and allow for easier entrance of foreign material? I currently teach my technicians to add the amount of grease as determined by the SKF formula G = DB/10, where G is grease in ounces, D is bearing outer diameter, and B is bearing width; or as I've read in Lube-Tips, one shot per inch of shaft diameter. Is this not enough in dusty environments?"

Several factors influence the quantity of grease that would go into a bearing at the selected interval. Critical factors include:

1. Design of the bearing (plain, roller, ball or spherical roller).

2. Type of shield used in the bearing.

3. Size and speed from which to calculate dN values.

4. Viscosity of the lubricant in the grease.

The Dodge Type-E bearing has a shield and lip seal configuration, with an option for an additional two-stage lip seal. This type of seal, by design, will allow for discharge of grease without damage at the outer perimeter of the seal. You could consider this a type of shielded bearing configuration.

A SEALED bearing is not designed to be purged. If you apply too much grease too quickly, you can rupture the seal and compromise the life of the bearing.

If you look closely at the manufacturer’s guidelines, you should see both general and specific directions for relubrication, including frequency and quantity for a given speed and load. The OEM parameters are typically the best starting point for relubrication practices. The OEM will also suggest that if you have a highly aggressive environment that it may be necessary to adjust the interval or volume to increase the amount of grease to the bearing. The SKF formula also provides a good starting point. Again, the calculated value must be adjusted to accommodate the environment.

The decision to flood or purge a bearing should be taken within the context of bearing construction, production environment and OEM guidelines. This is rarely a simple question.

Mike Johnson, Noria Corporation

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