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).
The specifications and testing procedures for sample Phantom III clutch springs.
| Identifier | ExFiles\Box 93\3\ scan0433 | |
| Date | 9th May 1938 | |
| 3/2 RHC{R. H. Coverley - Production Engineer}/Mr, Base. Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}1/JH.9.5.38. Phantom III Clutch Springs. Herewith are 6 sample springs supplied by the Tempered Spring Co. Sheffield, and made from Oil Tempered Swedish Wire. 3.G.85733 134 lbs. ± 6 at 1.625 length. Free length on drawing is 2.229. but makers state 2.279 approx. 3.G.85734 150 lbs. at 1.625 length, Free length on drawing 2.301 but makers state 2.342 approx. Please inspect, and record free length of each before testing. Test by compressing to 1.500 (which is just over the solid length) a number of times, and then test poundage at 1.625 and check up free length. If this still agrees fairly closely with free length stated by makers, we will modify the drawings to suit. Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler} | ||