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).
Various engine components, focusing on the development and performance of big end bearings.
| Identifier | ExFiles\Box 27\3\ Scan213 | |
| Date | 15th May 1939 guessed | |
| 7. Groves carburetter, Scintilla twin magneto, with 2 distributors, mounted on the reduction gear case to simplify harness. The model seen was fitted with a Coffman starter; it has a steel crankcase and dynamic suspension fitted to the cylinder heads of the rear row. Front and rear exhaust ring will be fitted to simplify manifolding. See 'Aeroplane', June 7, 1939. Consolidated '31' Flying Boat. ENGINE COMPONENTS Big End Bearings Both Wrights and Pratt & Whitney are getting excellent results with their fixed big end bearings. Wrights are still using copper lead containing 26 to 31% lead, but they have improved its performance greatly by adopting end seals based on the Bristol pattern. The bush has a life in Service of at least 1500 Hours. This statement was checked at several sources. After the 7 hour endurance test the bearingshowed the typical blue black bloom but it was badly scored. This was put down to dirt in the engine and it was stated that the scoring healed up, which certainly appeared to be true from the appearance of much older bushes. Pratt & Whitney have had Service experience with 2500 Bearings over one year with the silver big end bush. After 1550 hours a bush which we saw was in excellent condition, apart from extraneous metallic particles which had become embedded in the metal without, however, causing any distress. Pratt & Whitney have done a great deal of work on this bearing, and it has gone through 3 stages. Pure silver is felt to be bad, as although satisfactory results can be obtained it behaves erratically, sometimes scoring badly. The next stage was to coat the bearing with lead. This gave it good bearing qualities, but made it more susceptible to corrosion. The present stage, which is giving very good service indeed consists of coating and bearing with lead and then diffusing the lead into the silver, after which some secret process is applied which definitely prevents corrosion. Pratt & Whitney too are interested in the Bristol type of sealed bearing and have a | ||