Common sense guidance for extending bearing life including links to resources that can help.

When sleeve bearings are rebabbitted or replaced, an important step during assembly is to check the contact between the sleeve bearing and the journal which rides in it. The use of self-aligning sleeve bearings (also called spherical or ball fit) renders this step almost unnecessary. Still, cylindrical sleeve bearings should be inspected to make sure the contact area is sufficient. This article is specific to checking and correcting the wear pattern when installing a new sleeve bearing in an electric motor.

Cuando se rebabitan o se reemplazan cojinetes de deslizamiento, un paso importante durante el montaje consiste en verificar el contacto entre el cojinete y el muñón del eje que monta sobre el. El uso de cojinetes de deslizamiento auto alineables (también denominados esféricos o de ajuste esférico) hace que este paso sea casi innecesario. Aun así, los cojinetes de deslizamiento cilíndricos se deben inspeccionar para verificar que haya suficiente área de contacto. Este es un artículo específico para verificar y corregir el patrón de desgaste al momento de instalar cojinetes nuevos en un motor eléctrico.

Two case histories point out the need for caution when working with metal sprayed shafts:

• Example 1: When measuring the bearing fit shaft size, the micrometer didn’t feel right; mushy, not solid, although the journal was very close to the specified size. After using two micrometers to experiment with one of these frosted fits, it was discovered that the measurement on one micrometer changed when tightening down the other micrometer and vice versa.
• Example 2: The bearing journals on a large armature began to fail while the armature was coming up to speed in balance stand.

Member question: Can you settle a disagreement about the subject of sleeve bearing clearance? We have several contradictory guidelines, some of them from manufacturers. Which is best?

It is fair to say that our outlook on life is colored by experiences. In our industry, those experiences often are shaped by the customers we serve. A good example is this question about the proper clearance between a shaft and the sleeve bearing it rides in. Chances are each of us has a rule of thumb for bearing clearance, probably related to shaft diameter. They can't all be right, yet many of us may have used one of these rules (probably not the same one, either!) with great success. Which one, if any, is correct? The answer depends on the application.

Much of what is discussed in this article applies to all rolling bearings, both ball and roller. Our focus, though, will be on issues that relate mostly to ball bearings used in electric motors. The intent is to address some of the fundamentals of rolling bearing enclosures, internal clearances and fits. We deal with rolling bearings every day, but we don't always consider some of these fundamentals until there is a bearing-related problem.