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 report on a 20 HP fine pitch rear axle pinion, comparing the durability of air-hardened steel versus case-hardened steel.
| Identifier | ExFiles\Box 49\2\ Scan178 | |
| Date | 1st November 1923 | |
| X4256 To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c.c. to CJ. c.c. to Rg.{Mr Rowledge} c.c. to K.{Mr Kilner} c.c. to Da.{Bernard Day - Chassis Design} c.c. to HY.{Tom Haldenby - Plant Engineer} 20 HP. REAR AXLE. X4256 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} | ||