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).
Production issues and endurance testing of connecting rod little end bushes.
| Identifier | ExFiles\Box 132\2\ scan0242 | |
| Date | 21th April 1938 | |
| 1119 To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. RHC.{R. H. Coverley - Production Engineer} c. HPS.{Horace Percy Smith - Experimental Factory Mgr} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}1/AP.21.4.38 CONNECTING ROD LITTLE END BUSHES. In view of troubles experienced on production in fitting the little end bushes in the connecting rods with an interference fit and boring in position, semi-floating i.e. hand press fit bushes were run on our last Wraith endurance unit. The bushes in question were a selective fit and approximate to .0001 clearance. After 40 hours endurance all, with the exception of No.3. were still tight in the rods, No.3. having .0002 clearance and we say, therefore, that they were a satisfactory job. A further set of bushes were similarly fitted to B.III. No.1. unit which has now run a total of 100 hours on the test bed and we will inspect these bushes during the next day or so. If these prove satisfactory, then are selective fit bushes as we have run them, a production job and any advantage over the present method.? If not, then we shall have to run with varying clearances say size and size, ¼ thou. clearance, and ½ thou. clearance as we have no knowledge as to what clearance can be given without bringing up piston knocks. The position, therefore, is that if the B.III. unit reveals bushes O.K. we would be prepared to release size and size selective fit bushes for production, but if limits are required then more tests will have to be carried out and suggest that in this event the various clearance, as previously mentioned be incorporated on our next endurance engine (B.III. No.5. unit) Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||