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).
Change in steel type for back axle tubes and manufacturing methods.
| Identifier | ExFiles\Box 102\4\ scan0070 | |
| Date | 22th May 1931 | |
| R.{Sir Henry Royce} Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} Hy.{Tom Haldenby - Plant Engineer} Hs.{Lord Ernest Hives - Chair} Y5350. BY4/G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 22. 5. 31. 87350 X5350. 40/50 HP. & 20/25 HP. BACK AXLE TUBES. Referring to R4/M19.5.31. it is necessary in the first place to remind you that we changed from the .35 carbon steel to nickel steel for our axle tubes owing to a number of tube failures occurring at the collar retaining the inner ball bearing of the hub. It is true that we had also experienced complaints owing to the tubes bending as a result of side blows when the car skidded and hit the kerb, but the main cause of the change in material was due to a number of actual failures of the tube at the point indicated. One other point I would like to refer to again is that in the Banjo type of axle it is not an ordinary tube steel which is used but a specially produced low carbon steel having a carbon content not exceeding .15, with an ultimate tensile between 26 and 30, and a yield point verying from 16 to 18 tons. This steel in my opinion is definitely unsuitable for axle tubes, but it is the only steel that can be manipulated by the 'Scott' process for Banjo axles or special axle tubes. From your memo. referred to above, I take it that you want to try tubes produced by the 'Scott' process, which will have to be in the low tensile carbon steel in question. Our present form of axle tube, whether made in nickel steel or .4 carbon, which is the carbon steel normally used for axles of our type, is produced in an exactly similar way :- a/- The hot rolling of a length of tube just sufficient to make two axle tubes. The tube so formed is cut in half and expanded and flanged in special equipment for the purpose, and then swaged down at the axle arm end to the required general dimensions. In the case of the 20/25, a tube 3 1/4" diameter outside and 2 5/8" inside diameter is produced by hot rolling, as the foundation for the rest of the work. | ||