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).
Letter from Leyland Motors discussing the performance and failures of different engine bearing materials.
| Identifier | ExFiles\Box 115\4\ scan0086 | |
| Date | 18th June 1940 guessed | |
| Leyland Continuation of a letter From LEYLAND MOTORS LIMITED. (3) A.C. 9 definitely showed its superiority over RR.56 on test in Research Department, and when running on comparative test to determine limit of loading there did not appear to be to be anything to choose between A.C. 9 and copper-lead. It is admitted, of course, that Babbitt is superior to either copper-lead, A.C. 9 or RR.56 when it comes to boundary lubrication conditions, and this is what led me seriously to consider whether a copper-lead strip bearing, with a flashing of Babbitt might not ultimately be the most satisfactory arrangement. We wish to be completely open in our dealing with this bearing material and if it is proved that breakdowns can be looked upon as the result of initial faulty clearance, or temporary oil condition over which we have no control then, of course, we cannot hold the bearing material responsible for failure unless it is more critical under these conditions than its competitive bearing. It is admitted also that the percentage failures are extremely small, and we are now prepared to leave the case as it stands until such time as evidence is procurable that service results would warrant considering a change to bearing material type. This course we considered was desirable some two months ago, but we are not now prepared to make a change in view of the evidence available. It is intended that somebody from this Department shall go out and personally investigate the failures which have been reported from various operators. Further, we are selecting a number of machines which are in service and requesting that an examination can be made of engines which have completed mileages in stages on 10,000 miles. This is to determine whether oil condition deterioration has any bearing on isolated failures, and to obtain accurate measuring of the bores of the rods to determine whether there is any possibility of failure due to loose fitting shells and the like. I am extremely sorry, of course, that this position, as indicated in your letter to Mr. Spurrier, has arisen, and I will certainly do all I can to obviate the impression that | ||