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).
Unsatisfactory macrostructure and dimensional issues with a Bentley connecting rod forging.
| Identifier | ExFiles\Box 132\2\ scan0234 | |
| Date | 8th February 1937 | |
| General To Rm.{William Robotham - Chief Engineer} from HPS.{Horace Percy Smith - Experimental Factory Mgr} c. to RHC.{R. H. Coverley - Production Engineer} HPS.{Horace Percy Smith - Experimental Factory Mgr}3/VS.{J. Vickers}8.2.37. BENTLEY CONNECTING ROD FORGING TO LeC.4888. With reference to the above, we give below the report received from the laboratory after examination of the macrostructure. "We have examined the sample forging submitted to us and find that the macrostructure is unsatisfactory. The analysis is correct for S/N. We have seen Mr. Frobert and he informs us that even with the greatest care he could only make about 50% of the forgings free from obvious fault. He attributes the trouble to the design of the dies. There is a marked deflection of the material at one stage of manufacture due to an obvious defect in the die." In addition to the foregoing, the forging has been sectionalised and examined for linear discrepancies. The distance between the gudgeon pin and big end bores was found to be .050 in.excess of the specified dimension. Also the centre and outer webs are offset .015 from the centre line. As far as can be ascertained at the moment, the difficulties may be attributed to the impression being offset relative to the die block. Whilst in our opinion these dies will prove very unsatisfactory in their present state, it may be advisable to ask Messrs. Hughes Johnson to produce a few forgings in them to confirm these remarks before the dies are resunk or scrapped. It should be noted that the representatives of Messrs. Bretts, who produced these dies, failed after three days to produce a single acceptable forging. HPS.{Horace Percy Smith - Experimental Factory Mgr} | ||