From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Characteristics and applications of plain bearings and surface finishes.
| Identifier | ExFiles\Box 178\2\ img085 | |
| Date | 7th February 1940 | |
| -4- Rm{William Robotham - Chief Engineer} Plain Bearings and Surface Finish OY 3/DS/Feb 7 40 (f- In the average plain bearing with something approaching ideal film lubrication there is little doubt that smooth finish is an advantage in low friction, longer life and freedom from seizure. When such surfaces are produced on a hardened pin in a hardened tappet roller, for example, the necessary clearance for an oil film must be studied more carefully than before. A definite 1/2 to 1 1/2 thousandth difference in diameter has to be provided for oil. (g- Very accurate surface finish indicators such as the Brush surface analyser are now available at moderate prices. They are being widely used in the industries. (h- The chemistry of bearings is at least as important as the mechanics and metallurgy. All good bearing metals were found to lie in one corner of the Mendeleef tables. (i- Anti-friction bearings are badly named. In many localities where they are used their friction is higher than plain bearings. They are necessary: To carry heavy loads at zero speed or low speed To work frictionlessly under light loads as in instruments To function in places difficult of lubrication To operate in places where design makes a properly proportioned plain bearing impossible ( such as the side rods of a locomotive ) Heavily loaded anti-friction bearings produce "flow-metal" on the raceway surfaces even when these are mirror finished before use. (j- The effect of fit has to be studied for individual cases. For example, injection pumps will do the work "For ever" if plunger clearance is kept within 3/4 of one tenth (.000075). If clearance greatly exceeds this plungers will score. (k- Of the bearing metals high lead or high tin white metals are the best. It is only where these will not function however well applied, due to particular conditions, that the others, copper-lead, silver, aluminum-tin, are justified. Copies to: J.M.Lessels S.E.Blackstone OY | ||