Abstract
This investigation concerns research on the polymethyl siloxanes or dimethyl-silicone polymers, and their uses as lubricants and hydraulic fluids. It is shown that these new fluids give excellent results when operated in a standard aircraft-type Pesco gear pump. It was found that the silicones when used in a gear pump fitted with cast-iron bushings caused serious wear and disintegration of the bushings at pump pressures of only 600 psi. It is concluded that the loaded surfaces of steel sliding on cast iron or on steel are not adequately lubricated by the silicone fluid, whereas steel sliding on bronze is effectively lubricated. A simple manually operated slider-and-plate test method was discovered capable of permitting the discrimination between good, bad, and indifferent bearing combinations for use with silicone fluids. Results with 156 combinations of metals are summarized. There is also given a means of relating these observations to the practical problem of selecting suitable metals for use in lubricating the sliding parts of machinery with silicones. The results are related to observations on the choice of suitable metals for gear pumps, piston pumps, and journal bearings. It is shown that the same conclusions relative to steel sliding on steel or on bronze are reached from tests with the Vickers piston pump.
