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).
Micro-examination report on a steel ball from a Ransome & Marles bearing.
| Identifier | ExFiles\Box 142\3\ scan0133 | |
| Date | 25th February 1937 | |
| 1204 Micro-Examination Report. M.1264. To Rm{William Robotham - Chief Engineer} c. Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} HL4/AG.25.2.37. Laboratory. STEEL BALL FROM RANSOME & MARLES BEARING. (Your ref: Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer}15/JH.23.2.37) This ball was split diametrically. One half has been examined microscopically and appeared to have a soft layer at the surface about 0.001" deep. This is shown dark in the photomicrograph No. A.1567. X150. The hardness of the interior was 950 V.P.N. (30 Kg) whilst the surface gave 858 V.P.N. (5 Kg). In spite of the low loading used for this latter test the true hardness figure is probably much lower. The soft layer is too thin for the test to be unaffected by the hard core when using a 5 Kg. load. Similar tests made on an ordinary 0.250" ball taken at random from stock gave 920 V.P.N. (30 Kg) on the interior and 928 V.P.N. (5 Kg) at the surface. No evidence of any other fault in the ball was observed. Photomicrograph No. A1567 att. (2 copies) Hl. He. | ||