Roller Bearing Diagnosis

    Roller Bearing Construction

  1. To understand how a roller bearing fails, it's best to also understand how it's constructed. The bearing itself consists of a set of rollers kept in place by a circular cage. This cage sits inside a bearing race, which provides a hard outer-edge covering to the bearing. Inside the center of the circular cage is the inner race, which connects to whatever the bearing is posted onto, usually an axle of some sort. The entire assembly is frequently encased within sidewalls, but not always. Ball Bearing ,Ball Bearings , 608 bearing , Mini bearings

    Environmental Conditions Create Problems

  2. Roller bearings, like many other bearings used in industrial settings, take a heck of a beating. Many times starting from an inactive cold condition, these bearings must then rotate either under extreme weight pressure or at high rotational speed, subjecting the parts to extreme heat and friction. One common example of roller bearing function is in providing the rotational ability of an engine flywheel. The flywheel starts and stops and revs at the speed of the engine, rotating the weight of the flywheel constantly to generate electricity. Over time, this activity creates significant wear on any bearing. Additional factors such as temperature, climate, moisture and dirt or grit only add to the abuse.

    Bearing Play

  3. A common sign of worn roller bearings comes in the form of bearing play or sloppiness in the bearing function. At high speeds, the bearing will put out a significant amount of noise from errant grinding as a result. Diagnosis can confirm this situation by looking for wiggling or looseness in the part in which the bearing sits. If the sloppiness or play is excessive the housing part will move far more than suggested tolerances and the bearing should then be removed and replaced.

    Noisemakers

  4. Roller bearings operating in the presence of grit, broken parts or failing components are also candidates for failure. Unlike the rotational sound emitted with bearing play, destructive material in a roller bearing results in a sound and feel like grinding. This, in short, is the grit and the bearing undergoing slow disintegration. Eventually, enough damage occurs that the bearing will jam up and essentially explode under pressure, causing whatever machinery in which it's installed to also stop moving.

    Finding the noisy bearing can be a difficult matter, however. With an assembly or engine that has multiple bearings, the failing roller bearing can transmit its grinding through other parts, masking its location. If possible, as on small engines, mechanics sometimes swap out all the bearings involved since it takes as much work to do one bearing fix as three in the same assembly.

    Bearing Race Failure

  5. The outer part of the bearing and inner ring provide protective surfaces for the bearing assembly. The parts, called the inner and outer bearing race, can crack under pressure or slip and burn in friction. The races are designed to fail faster than other parts of the bearing. This allows the bearing to take the brunt of the damage before other engine parts do. Surefire signs of race failure include burn marks, flaking of material, pitting and sometimes melting.

    Grease It

  6. Bearings live and die on lubrication. While they spin great on their own, under high heat and pressure bearings will quickly seize up without grease. Most roller bearing installations require the addition of high-temp bearing grease. Even used bearings void of any dirt can have their lives extended by just reapplying new grease in them. This procedure is commonly referred to as repacking the bearings. Lack of grease and dryness shows signs of bearing wear, signaling the need for closer examination and sometimes replacement.