When running grease-packed bearings at higher speeds (in excess of 5000 rpm), experiment with the quantity of grease in the bearing. A 10 percent change in the quantity of grease can drastically affect the amount of heat generated by the bearing (even as much as 40F depending on how close to optimum you are). If there is too much grease for the bearing to push out to surrounding pockets, the bearing will heat up quickly.

Often the optimum amount of grease is less than what you might think. Be sure to provide a sufficient run-in period for the bearing to position the grease before exposing it to full-time duty. (Jason Moe, Woodward Governor Co.)

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Interpreting the results of an oil analysis - an entire page filled with numbers - can appear to be a formidable task to the untrained eye. But like every other complicated task, by breaking it down into manageable parts, the job can be simplified, which makes the outcome more accurate.

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"I've heard of a few refineries that perform a cigarette paper test on their cylinders. What exactly is that?"

To check cylinders for the proper lubrication rates, the cigarette paper test method can provide a practical indication. To perform this test, follow these steps:

Relieve and vent all pressure from all cylinders. Remove the head-end head and position the piston at approximately the inner center, for the cylinder to be checked. Lock-out so that the crankshaft cannot be accidentally turned. Place together two layers of regular, unwaxed, commercial cigarette paper. Wipe the top of the cylinder bore with both papers, using light pressure in circumferential motion through approximately 20 degrees. The paper next to the bore should be stained (wetted with oil), but the second paper should not be soaked through.

Repeat the test at both sides of the bore approximately 90 degrees from the top, using two new clean papers for each side. When the paper next to the bore is not stained through, it may indicate underlubrication. When both papers are stained through, it may indicate overlubrication. In either case, it is recommended that the lubrication rate be changed accordingly, and that all cigarette paper tests be repeated until passed.

Repeat for all cylinders. If a reduction or increase of the lubrication rate is indicated for a cylinder, change in five-percent increments by adjusting cycle time at the force-feed lube pump. Repeat oil film testing for the cylinders affected, after 24 hours of operation.

Note: The cigarette paper test only gives an indication of oil film quantity. Aftermarket devices that measure flow are also available. Neither method indicates viscosity quality. Oils diluted with water, hydrocarbons or other constituents may produce what appears to be an adequate film or flow. However, the oil film may not have the required load-carrying capability due to the dilution.

- Jeremy Wright, Senior Technical Consultant, Noria Corporation

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