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).
Test results comparing the durability of an air hardened steel pinion with a case hardened one for a 20 HP rear axle.
| Identifier | WestWitteringFiles\K\November1923\ Scan76 | |
| Date | 1st November 1923 | |
| ORIGINAL To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c.c. to CJ. c.c. to Rg.{Mr Rowledge} c.c. to E.{Mr Elliott - Chief Engineer} c.c. to Da.{Bernard Day - Chassis Design} c.c. to SY. Hs{Lord Ernest Hives - Chair}4/LG26.11.23. 20 HP. REAR AXLE. 4256 We have tested the fine pitch rear axle pinion made from the air hardened steel. This gear failed after 19 hours 1st. speed, maximum torque. The case hardened pinion of this type only lasted 5 1/2 hours. The air hardened steel shows up to be a greater advantage on this comparison than it did with the coarse pitch gears. Hs.{Lord Ernest Hives - Chair} | ||