A Corning Revolution in Lubrication P ETROL and rubber are being
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turned almost inside out and astonishing properties revealed or chemically-imparted.; in a similar Way lubricants are receiving attention to fit them for the _greatly increased duties that are now being imposed on them.
Almost the sole lubricant of running.machinery to-day is oil. There are small-scale alternatives which, in time, may grow; graphite is one of them; it is generally used in a colloidal condition, either with water or oil. In some cases, water alone is used, particularly in the case of plastic bearings, which are now becoming fairly largely employed for rolling mills. Another form of metal-impregnated graphite, made from powders and compressed into solid bushes, is coming into use with no external lubrication, chiefly for slow-speed bearings exposed to heat which would vaporizeoil.
Recent patents have claimed several totally dif ferent systems of lubrication. One proposes a magnetic centralizing effect on a shaft and beating, thus preventing any metallic contact. Another states that a 4i-in. diameter shaft has been run at 20,000 r.p.m. lubricated solely by compressed air. Incidentally, as long ago as 1897, compressed air is referred to by Hersey as a possible means for lubrication which was then undergoing experimental 'research. • Fundamental changes in the general principles of lubrication can and will occur as a result of research into -the character of contacting surfaces —cylinder and piston, shaft and bearing. Smooth .surfaces and an interposed oil film form the basic theory. • -The Chrysler concern, in the U.S.A., has demonstrated that no such conditions have ever existed in a new-machine; that the normal bearing surface consists of a series of ridges which puncture the oil film in hundreds of places, permitting metal-to-metal' contact, obviously resulting in enormous pressures at these hundreds of points. It has, in fact,. been stated, by this company's investigators, that only 5 per cent. of such a surface is the normal extent affording a. useful bearing.. Suitable wearing properties have been attained only by •" running-in !' and consequently reducing the ridges; this, however, has the effecti of degroying -dimensional -accuracy', and thus_ contributes, to an -important extent, to the shortening of the life of -the machine.