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).
Valve bounce tests comparing Ph.III and Swedish wire double springs.
| Identifier | ExFiles\Box 109\4\ scan0103 | |
| Date | 29th June 1939 | |
| -3- Rm{William Robotham - Chief Engineer}/Swd1.2/WH.29.6.39. VALVE BOUNCE. The tests were commenced with 4 inlet valves having the adapted Ph.III double springs and the remaining four with Swedish wire double springs (EB.4678/9) which have anti-surge close pitch coils at the base and are parallel springs. Actually, the latter were designed for the B.V. engine, and in consequence the loads are too low for the B.80 unit, the valves commencing to bounce at 4200 R.P.M. whilst the Ph.III springs run up to a bounce speed of approximately 4500 R.P.M. The object of trying the EB.4678/9 springs was that occasional failures occurred on the Ph.III springs during a 50 hour endurance, together with bad surge periods, also the same springs are a 'mock up' in regard to their adaption on this unit. The comparative loading of the springs is - Ph.III. EB.4678/9 Seat loading 58 lbs. 41½ lbs. Full lift .4 loading 176 " 130 " Valve bounce 4500 R.P.M. 4200 R.P.M. In conjunction with our request memo Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} 2/WH.9.6.39. on the double valve springs EB.4678/9, i.e. top spring washer to suit alum oil sealing disc EW.2260, and single bottom washer to house both springs without any grummet, we should like alternative springs as follows for trial. These should be urged in order that they can be fitted to 30.G.VII in France. (a) Existing springs with increased free length to give seat loading of 55-60 lbs. providing the choc-stress is not excessive. (b) Higher rate springs with Ph.III loadings, closed and open, which have been verbally discussed with Da{Bernard Day - Chassis Design}/AM. | ||