From "Lubrication Fundamentals"

Many open gears, whether operating outdoors or indoors, are exposed to dusty and dirty conditions. Abrasive dust, adhering to oil-wetted surfaces, will form a lapping compound that causes excessive wear of the teeth. When viscous lubricants are used, the dirt may pack in the clearance space at the roots of the teeth, forming hard deposits. Packed deposits between gear teeth tend to spread the gears and overload the bearings. These deposits that build up in the tooth root area, if hard enough, can also lead to tooth wear and possible breakage.

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Test your knowledge and prepare for ICML lubrication and oil analysis certification.

QUESTION: What are the two functions of a crankcase oil detergent additive?

Get the answer.

"What size micropatch filter should be used to microscopically analyze wear debris with an on-site oil analysis rig?"

It is important to select a patch with the appropriate pore size focus. Let's consider some rules of thumb:

1. For clean systems that utilize high-quality filtration, a two-micron patch is preferred so you can view the smaller particles that might be generated during the early stages of failure. The small particle size focus also enables you to generally assess the system's overall cleanliness.

2. Also, for clean systems - particularly hydraulics systems - periodically inspect the oil using a 0.8-micron patch to determine if silt is accumulating at high levels.

3. For other systems like engines and gearboxes, a five-micron patch is preferred. The larger particle size focus enables you to clearly view abnormal wear particles free from the clutter of accumulated small particles.

Here is a detailed procedure for using the patch test.

Drew Troyer, Noria Corporation

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