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).
Comparison of BHP loss from gear churning between a plain direct drive and a fully geared gearbox.
| Identifier | ExFiles\Box 145\2\ scan0199 | |
| Date | 31th March 1939 | |
| 1231 also 1153 To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. Da.{Bernard Day - Chassis Design} c. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} c. Da{Bernard Day - Chassis Design}/Hdy.{William Hardy} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}6/MH.{M. Huckerby}31.3.39. A comparison has been taken between running with a plain direct drive through the gearbox against a fully geared box also running direct. An average of several tests taken at 3500-4000 r.p.m. indicates that there is a 3 BHP loss due to churning of gears when running with Castrol XL at an oil temp. of 20°C. As near as can be measured this loss is reduced to 1 1/2 BHP at a temperature of 50°C and over. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||