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).
To Wellworthy Piston Rings Ltd. regarding main bearing clearances, scoring, and engine running-in procedures.
Identifier | ExFiles\Box 115\5\ scan0268 | |
Date | 29th April 1939 | |
-2- To Wellworthy Piston Rings Ltd. Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}1/JH.29.4.39. (7) Clearances (Cont'd). (b) Main Bearings. Minimum .0012/inch diameter. Maximum .00155/inch diameter. Preferred .00135/inch diameter. It should be noted that these clearances have been found suitable for our particular engine design, and other firms such as heavy duty engines have gone outside this limit with advantage.s (8) Scoring? We have stressed at all times that the question of filtration cannot be over-emphasized. Actually, we recommend the use of a filter of the Tecalemit type in conjunction with a good filter of the bye-pass type. Further points to note. If firms are willing to go to a little trouble in adapting the material to their engines, their bearing problems are generally solved, providing of course that the design is something reasonable in the first place. Clean lubrication, and plenty of it is the most important point. When fitted up in a new engine, a different method of 'running in' is desireable compared with White metal. For instance, simple light running is not enough. The engine should be 'run in' under a gradually increasing load and speed, until after say 5 hours full load at max. revs. has been reached. If after that time the engine tightens up clearances are not adequate. Rm{William Robotham - Chief Engineer}/C.T.Salt. | ||