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).
Phantom III valve failure during a 20-hour endurance test and comparison with a strengthened 25/30 HP valve.
| Identifier | ExFiles\Box 96\2\ scan0118 | |
| Date | 2nd July 1936 | |
| X354 To E.{Mr Elliott - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}8/KW.2.7.36. Phantom III Valves. After 20 hours endurance running on a Phantom III unit fitted with standard E.87424 exhaust valves, No. 2 B. side cylinder valve head broke off. The position of failure is shown on the attached sketch Rm.{William Robotham - Chief Engineer}175, on which we have also drawn the present 25/30 HP. exhaust valve E.61073 which is your latest strengthened valve. At the point of failure which is in the usual position of any valve failure; that is, where the radius of the head runs into the stem, the Phantom valve is less in diameter by approximately .025" than the 25/30. Since adopting the solid stem exhaust valve this is our first failure on Phantom III, it is also the first time we have been enabled to run under Bentley endurance conditions, each hour being composed of the following - 30 mins. at 4000 R.P.M. 25 " " 4250 " 5 " " 4500 " This endurance was in conjunction with Hall's metal big end bushes with strap type of rods and .125" reduced crankpin diameter in order to increase the strength of the bearings. So far as indicated by the running of the unit, these bearings gave no sign of trouble. A report will follow on their condition when examination and measurements have been taken. Hs{Lord Ernest Hives - Chair}/L.H.Swindall. | ||