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).
Specifications for two new springs designed for a lighting switch.
| Identifier | ExFiles\Box 168a\2\ img417 | |
| Date | 17th March 1939 | |
| To Rm{William Robotham - Chief Engineer}/RC.{R. Childs} BY/RD.3/B.17.3.39. Re: Lighting Switch - D.CD.834. As requested in your Rm{William Robotham - Chief Engineer}/RC.{R. Childs}7/JH.14.3.39., we give herewith particulars of two new springs to enable further experiments to be carried out on the action of the above switch. To keep the initial load at 5.2 lbs. and to fit in the space available, the spring rate will be 12.8 and 18.4 lbs/in. respectively as agreed. It is suggested that one of each should be made up by Mr. Base, as under :- No.1 Spring. Dia. of Wire 15 SWG. (.072) S/CS. Inside dia. 1.062 +.15. Free length .837 +.25. Load when deflected to .425 to be 5.2 lbs ±2 ozs. 2 Working coils with an extra coil at each end ground square, making 4 coils altogether. Rate 12.8 lbs/in. Max. load 5.84 lbs ±2 ozs. Max stress 45,000. Spring to be black enamelled. No.2 Spring. Dia. of Wire 14 SWG. (.080) S/CS. Inside dia. 1.062 +.15. Free length .700 +.25. Load when deflected to .425 to be 5.2 lbs. ±2 ozs. 2 Working coils with an extra coil at each end ground square making 4 coils altogether. Rate 18.4 lbs/in. Max. load 6.12 lbs ± 2 ozs. Max. stress 35,000. Spring to be black enamelled. BY/ | ||