Reservoir Pattern Used in a Helicopter Linkage Bearing

This highlights one of the limitations in using the technique of filling a lubricant supply into pockets in one of the bearing surfaces. The limitation is that lubricant transfer to the counterface can only take place when the lubricant source is in contact with the counterface. It follows that, in the absence of some mechanism such as that 

This has two important consequences for the design of the lubricant reservoirs. The first is that if the recesses containing the lubricant are deeper than the acceptible wear depth, then the deeper portion of the lubricant will be unusable. In Devine s work, the recesses, at 0.016 (0.4 mm) to 0.070 (1.8 mm), were much deeper than the permissible wear depth for the surfaces, presumably in order to give adequate lateral support for the composite material. 

Apart from the lubricant area fraction, the actual dimensions of the recesses are also important. Deep, narrow pockets are inherently likely to give strong support and retention of the lubricant material, but, as shown previously, deep pockets are wasteful of lubricant, while narrow pockets are susceptible to blocking with wear debris. On the other hand, wide shallow pockets are likely to provide poorer support and retention for the lubricant material. Wide recesses will also lead to a gross lack of uniformity in the surface strength of the bearing surface because the lubricant composite and the metal matrix are likely to have very different moduli. 

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Figure 8.5 Lubricant Reservoir Pattern Used in a Helicopter Linkage Bearing (Ref.210)...

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