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).
Technical discussion on the load capacity and wear characteristics of axle lubricants.
Identifier | ExFiles\Box 114\1\ scan0084 | |
Date | 11th January 1937 guessed | |
I do not propose to become involved in a controversy which may exist between lubrication experts; from the standpoint of the axle the only thing of importance is that the load carrying capacity shall be such as to prevent scoring and that the lubricant shall have no other detrimental effects. That there must be no other detrimental effects is most important. In considering the load capacity, all reference must not be directed to fresh lubricant; the load capacity after 10,000 more miles is just as important in its capacity before use. Its capacity to carry load in summer or winter and after long storage either in the factory, the service station, or in the axle are of paramount importance. For the measure of load capacity we have adequate testing facilities for the initial approval of a lubricant and so long as arbitrary conditions are established for the testing a fair index of the load capacity is obtainable; but to determine the stability of a lubricant in use over a period of time is a long process and an expensive one and too frequently impossible of duplication in all variables. Whatever may be the high load capacity of a lubricant unless it holds up during use, the axle designer cannot make full use of it and any great reduction in load capacity is certain to be indication of other forms of deterioration of the lubricant. There are various methods for rating the load capacity of lubricants, but not all laboratory tests are of value unless they accurately correlate tests of production axle units and road experience. LOAD CAPACITY There are various methods of determining load capacity of the lubricant by testing in full sized axles. A common test is to engage the clutch suddenly with the car running at various speeds in either direct drive or second speed while the motor is idling. This is a type of test which can be made as severe as desired. Caution should be exercised in making this type of test, that the severity shall not be greatly beyond what might be expected in normal service. In Figure 14 to 18 are shown various results on the pinion teeth using various types of lubricant. A much more reliable test and one which we have used for many years is to run the axle for nine hours on the drive side at full motor torque in second gear and one hour in reverse at the same load, maintaining some sort of artificial cooling, generally that obtained from circulating fans. Such a test gives more reliable information as to the items of stability, abrasiveness and chemical activity as well as to the load carrying capacity of the lubricant. WEAR I have on other occasions used the term abrasiveness to describe the influence of the lubricant on wear of axle parts and have been warned that this is not a proper term as "EP{G. Eric Platford - Chief Quality Engineer}" lubricants so-called are not abrasive. Here again is a controversial point of interest only to lubricant technologists and whether the lubricant is of itself abrasive or whether through some faulty mechanism in its operation it causes wear in the axle parts, the terminology is unimportant. The net result is undesirable and harmful. The postulation that "EP{G. Eric Platford - Chief Quality Engineer}" lubricants are not abrasive is not susceptible to proof. On the contrary there is much evidence to indicate that many of them are abrasive, whether they start out in the beginning that way or whether they become abrasive during use. The facts that axles wear more with some lubricants than with others, and more in summer than in winter is to me incontrovertible proof that some lubricants are abrasive and some more abrasive than others. - 9 - | ||