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).
Results of over 650 hours of endurance testing on 20/25 and Bentley engines.
| Identifier | ExFiles\Box 82\4\ scan0238 | |
| Date | 31th January 1936 | |
| x206 To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}11/KW.31.1.36. We have done rather more than 650 hours' full throttle endurance running at engine speeds between 4,000 and 4,500 revs. this year on the 20/25 and Bentley engines, mainly to evolve Hall's bearing metal. During these tests a number of other failures have occurred from time to time, and the attached print shows what these have been. Generally speaking, we find that 25 hours of this running is equivalent to 15,000 miles road testing, and some failures which have occurred at 50 hours and beyond have never been known to take place on the road. There are certain things we have got to improve, such as the driven plate of the spring drive, and we have certainly had more valve spring failures than we like. We are also on the border line with exhaust valves, and these of course are having attention. Bearings and crankcases have now reached the stage when they are probably the most reliable parts of the engine. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||