Sliding Interface

The most basic type of bearing is a plain sliding bearing as it contains no extra moving parts, instead relying on solid to solid contact. Failure of this configuration of lubrication is non catastrophic, with a gradual wearing over time.

A sensible configuration would have one of the two surfaces, the part which is easier to replace, being made of a softer material and hence designed to wear faster. Using a set of soft replaceable pads mounted on the stator supporting the rotor, this system could be designed for annual replacement.

Oil impregnated self lubricating chemically inert plastics are available for dry applications. The wiping action cleans the shaft of soft particles, whilst harder particles become embedded in the liner, eliminating shaft damage.

Figure 6.1: Manufacturers data on wear rate of solid contact bearings [83]

Figure 6.1 shows the results of a wear test on two commercially available solid contact bearings, carried out over 1050 hours (43 days) and a distance of 105 840 000 inches (2 600 km) [83]. The corresponding wear for the two materials is 0.0055 and 0.001 inches (0.14 and 0.025 mm). If the wear rate were linear then it could be assumed that it is possible to manufacture a bearing capable of travelling 10 000 km with a wear of just 0.1 mm.

Examining the least worn of the two, which is designed for use with hardened steel shafting and ceramic coated shafting, the maximum speed for intermittent load is given as 4.2 m/s, whereas the load capacity can be equal to a maximum pressure of 200 bar [83].

These chemically inert linings could clearly be suitable for use in this application, although some communication would be required with the manufacturer as to the effect of being permanently submerged in saline solution during their life time. They necessarily enforce regular maintenance of the device, but it appears to be possible to limit this to annually.

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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