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).
Experimental modification to valve spring RS.500 to increase its seat load.
| Identifier | ExFiles\Box 96\2\ scan0230 | |
| Date | 29th May 1937 | |
| To HPS{Horace Percy Smith - Experimental Factory Mgr}, Copy to Ey. Rm.{William Robotham - Chief Engineer} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} 354 E/PSN/AHF.1/M.29.5.37. PH.III. VALVE SPRINGS. Modification to Spring RS.{Sir Henry Royce's Secretary}500 to give 45 lbs. Seat Load. As a result of test on Valve Spring RS.{Sir Henry Royce's Secretary}500 which gave a bouncing speed of 4300 R.P.M., we are issuing herewith two prints of the following details which increase the seat load from 40 lbs to 45 lbs as an experiment:- RS.{Sir Henry Royce's Secretary}540 - Valve Spring. RS.{Sir Henry Royce's Secretary}541 - Valve Spring Washer (Top). which have been detailed from the scheme LeC.5696. The spring is similar to RS.{Sir Henry Royce's Secretary}500 in having uneven coil spacing and being of the closed ended type, but has seven total coils and is arranged to give 45 lbs. load on the valve seat. Owing to the increase in spring length entailed by the extra coil, it has been necessary to provide new spring top washers and to revert to the valve guides E.88705 which were detailed from LeC.5417. This spring has a much reduced stress and is of a lower rate than RS.{Sir Henry Royce's Secretary}500. Will Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} please instruct these parts to be made when required. The valve springs RS.{Sir Henry Royce's Secretary}500 can be pulled out .025"t to give a seat load of 45 lbs. with the present top washers and guides to LeC.5432, but when in this condition they give 149 lbs. load with the valve open and a corresponding corrected stress of 98,000 lbs/sq.in. They must, therefore, never be allowed to become chocked. E/PSN. | ||