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).
Testing, adoption, and trials of different valve springs for various car models.
| Identifier | ExFiles\Box 158\4\ scan0207 | |
| Date | 31th January 1938 | |
| To By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} 1360 Rm{William Robotham - Chief Engineer}/Swd1.16/JH.31.1.38. VALVE SPRINGS. Based on the successfull 15,000 miles tests on 6.B.IV and 3.B.IV with Swedish wire springs as bought from the Tempered Spring Co. a standardisation sheet was issued for adoption on the Bentley. It was decided to release 50 sets of springs and without a test on the 25/30 these were allotted by someone for 25 - 30 H.P. and 25 Bentley chassis. One spring has failed on a 30 H.P. chassis GLP.23 but up to the moment we have not heard of any failure on the Bentleys in service which have these springs fitted. As we have not even continued using these springs on the Bentley for which they were proved, our provisional specification on Wraith for the 6 cars built by RHC.{R. H. Coverley - Production Engineer} calls for springs in S/CV. We are however sending out for fitment and trial on 26.G.VI, 6 springs in Swedish wire coiled by R.R. and 6 in Swedish wire as made by the Tempered Spring Co. These are to EB.3256 having close coiling of the 2 bottom coils. If these springs go through the 15,000 miles without failure then we should suggest instructing them for the 100 sets. In the meantime we are going to try omitting the bottom grummet in conjunction with the increased space available, use lower stress springs EXS.313 in "Swedish Wire" evenly coiled as EB.175 with surge dampers EXS.312 (as per OLDSMOBILE) which also act as bottom positioning washers for the springs. The above scheme will be cheaper and more reliable as in addition to less parts springs produced with even coiling are cheaper than springs with uneven coiling and the difference would pay for the surge dampers. By/B. has designed several alternative springs with uneven coiling for trial on Bentley III. | ||