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).
Bulletin on the mechanics of lubrication and the application of colloidal graphite to industry.
| Identifier | ExFiles\Box 145\3\ scan0010 | |
| Date | 1st January 1931 | |
| TECHNICAL BULLETIN No. 200.6 temperature, indicates clearly the influence of the graphite, ***** but the observation of special interest in this test is the permanence of the graphoid surface after the supply of lubricant was discontinued.” More recent tests carried out by Stanton and Jakeman at the National Physical Laboratory, London, have confirmed Mabery's findings and have gone a little further in an interesting direction. The tests demonstrate the remarkable strength of the graphoid surface formed by using colloidal-graphited oil. This graphoid surface, is held in place by molecular forces and its presence proves that colloidal graphite lubrication is far superior to that obtained when an ungraphited oil is employed. Quite apart from improved lubrication the test illustrated that there is greater safety in using colloidal-graphited oil and that it is possible to run a bearing with a much smaller feed than is required with plain oil. Figure 4 Graph details: Y-axis 'Coef. of Friction', X-axis 'Time in Minutes'. Lines for 'No.1 Coefficient of Friction of Oil Alone' and 'No.2 ... and Graphite'. Conditions: 'Pressure on Bearing 200 lbs. per sq. inch', 'Feed 8 drops per min.', 'R.P.M. 450'. Event marked at (S) 'Oil Supply Shut Off'. Saytzeff¹⁰ found that after the bearing surfaces had secured the adsorbed graphite, the friction decreased approximately 30%. In all cases the addition of 1 to 2% of graphite suspension† resulted in an appreciable reduction in oil consumption. The results of these investigators are borne out in practice where the reduction in the coefficient of friction, accompanying the use of colloidal-graphited oils, is reflected in lower power bills, fewer mechanical replacements and a decrease in oil consumption. †The term “graphite suspension” refers to a concentrated colloidal solution containing approximately 10% graphite. REFERENCES ¹J.{Mr Johnson W.M.} Am. Chem. Soc., 38, 2221 (1916); Ibid., 39, 1848 (1917). ²Ibid., 38, 2267 (1916) or Chem. News, 116, 152-3 (1917). ³Chem.-Ztg., 40, 358-9 (1916). ⁴Phil. Mag., 38, 32 (1919). ⁵Proc. Roy.{Sir Henry Royce} Inst. Gt. Br.{T. E. Bellringer - Repair Manager}, 1920. ⁶Phil. Mag., 40, 201-11 (1920). ⁷J.{Mr Johnson W.M.} Soc. Chem. Ind., (1920); or Chem. News, 120, 244 (1920). ⁸Chem. News., 120, 269-70 (1920). ⁹J.{Mr Johnson W.M.} Ind. Eng. Chem. 5, 717-23 (1913). ¹⁰Z. Ver. deut. Ing., 58, 1174 (1914). Oildag* is the brand of Colloidal-Graphited Oil Manufactured by E.{Mr Elliott - Chief Engineer} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Acheson, Ltd. *REGD. TRADE MARK. Additional copies of this Bulletin may be obtained from E.{Mr Elliott - Chief Engineer} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Acheson, Ltd., Thames House, Millbank, London, S.W.1 Balding & Mansell, 4 Snow Hill, E.C.1. Printed in England. --- TECHNICAL BULLETIN Pertaining to the Application of Colloidal Graphite to Industry Issued by E.{Mr Elliott - Chief Engineer} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} ACHESON, LTD. LONDON Copyright 1931 By E.{Mr Elliott - Chief Engineer} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Acheson, Ltd. FILE INDEX Lubrication Colloidal Graphite Theory "Oildag" Number 200.6 THE MECHANICS OF LUBRICATION WITH COLLOIDAL GRAPHITE A question frequently asked is, “Why does the addition of colloidal graphite to ordinary lubricants increase their efficiency ?” The following article has been prepared to serve as a detailed reply to that query. CONCERNING SURFACE ENERGY OF SOLIDS To explain why the addition of colloidal graphite to ordinary lubricants increases their efficiency to such a marked degree, reference is first made to the seemingly remote subject of crystal analysis. Laue conceived the idea of using a crystal as a grating in connection with X-ray study. The crystal was used as a substitute for the fine-ruled grating employed to set up diffraction effects as obtained with ordinary light. He found that when a pencil of X-rays was directed against a crystal, the reflected rays, which were permitted to impinge upon a photographic plate, formed a symmetrical pattern (Fig. 1). Laue interpreted this as a method of studying the orientation of atoms in crystals and formulated a theory in this connection. W. L. Bragg revealed certain errors in Laue’s theory and subsequently offered a theory of his own which has proved to be accurate, and which makes possible the determination of crystal structure from the diffraction pattern. Figure 1 Figure 2 Na{Mr Nadin}=Sodium Cl=Chlorine The structures of numerous compounds have been studied. Sodium chloride, or table salt, has been found to consist of planes of atoms equidistant from each other, in which the sodium and chlorine atoms are situated alternately and so spaced as to constitute a lattice. The small cubes, formed by the intersection of planes (Fig. 2), have four atoms of sodium and four atoms of chlorine alternating at their corners. This arrangement causes each sodium atom to be surrounded by six chlorine atoms, and each chlorine atom, in turn, to be surrounded by six sodium atoms. | ||