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).
Corrections for a valve comparison sheet and comparing different exhaust valve designs.
| Identifier | ExFiles\Box 106\5\ scan0160 | |
| Date | 29th April 1936 | |
| BY.{R.W. Bailey - Chief Engineer} from E.{Mr Elliott - Chief Engineer} c. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} SWDL.{Len H. Swindell} E.7/HP.29.4.36. re 25-30 HP. Exhaust Valves. With reference to the valve comparison sheet which we inspected this morning, there are two points which require correction:- Firstly, all the valves should be shown at the same height relative to their seating faces instead of to the crown of the head, to be a strictly good comparison. Secondly the point of failure shown on the diagram is one measured from a Bentley valve and not from the valve which broke on 22-C-V.{VIENNA} The latter actually should come 1" nearer the head, or .1" at full scale. With the fracture in the correct position the improved valve LeC.5082 is actually .050 larger in diameter at the line of the fracture, and the further design LeC.5097 with modified taper stem is .075" larger at this point. Thus, the originally instructed valve LeC.5082 had 30% more area at the fracture than the one we are now using. LeC.5097 has 45% increase. The Bentley valve which fractured is one that had done 200 hours endurance, so that we should not attach too great importance to this. One point, however, is significant, the Bentley fracture occurs where the radius finishes on the valve stem, and also 22-C-V fracture occurs in a similar location. We, therefore, think the modified taper on the valve stem of LeC.5097 is worth having for the small additional weight involved as a safeguard against localisation of the fracture at the bottom of the radius, which might well occur with the small change we are able to make in the position where the parallel finishes by varying the radius alone. I am attaching to BY's copy of this memo the original of LeC.5097 for instruction. E.{Mr Elliott - Chief Engineer} | ||