FUNDAMENTALS OF LUBRICATION: PART FOUR. LUBRICANT TESTS THEIR PURPOSE AND SIGNIFICANCE

IN THE concluding paragraphs of the preceding section (October issue) a brief mention was made of grease tests of a special type by which service behaviour under certain conditions—at high or low temperature for example—could be forecasted. This sort of lubricant testing which attempts to simulate actual service conditions, but accelerates them, is a typical feature of today's practice both in the oil industry and also in the laboratories of lubricant users. In fact, so far as lubricating greases are concerned, it was users (in this particular instance the manufacturers) of ball and roller bearings, who were the pioneers in the field. This is understandable, for the overwhelming majority of anti‐friction bearings are grease lubricated and before the maker can give his recommendation for any particular grade, he must make sure that it will give satisfactory service under the anticipated operating conditions. Certain test machines, which naturally incorporate ball or roller bearings, have become so well known that they have been adopted as official standards in some countries.