Failure of a Bentley crankshaft due to an unsatisfactory nitriding process, resulting in insufficient hardness.
| Identifier | ExFiles\Box 85\5\ scan0133 | |
| Date | 2nd December 1937 | |
| 294/217 Rm {William Robotham - Chief Engineer} /GWH. {George W. Hancock - Head Chateauroux} c. RHG. c. Rm. {William Robotham - Chief Engineer} BY.14/G.2.12.37. BENTLEY CRANKSHAFT FROM B.102-KT. - MILEAGE 4900. Referring to your memo Rm {William Robotham - Chief Engineer} /GWH. {George W. Hancock - Head Chateauroux} 16/N.22.11.37. we confirm your findings in every respect. The cause of the trouble is the furnace used is not giving a satisfactory circulation of ammonia during the nitriding period. Mr. Talbot found this was occurring from our routine tests in January of this year and returned between 30 and 40 shafts for retreatment. Apparently this shaft escaped detection, but we do not anticipate an epidemic, we think the shaft in question is an isolated case. We have again raised the matter with Sheepbridge Stokes, who nitride all our shafts, as we recently found one or two shafts which were not sufficiently hard, falling below 550 brinell. It is quite clear that aluminium alloy main bearings will not give satisfaction unless the journals show a hardness figure of 600 as a minimum, and we are insisting on this figure being maintained. By BY. {R.W. Bailey - Chief Engineer} | ||
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).