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).
Redesign of a magnetic cutout for a green light charge scheme, addressing issues with road vibrations and coil materials.
| Identifier | WestWitteringFiles\S\2April1928-June1928\ Scan130 | |
| Date | 15th June 1928 | |
| EFC. FROM R.{Sir Henry Royce} [Strikethrough]C. to BJ. HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer}[/Strikethrough] ORIGINAL. R3/M15.6.28. GREEN LIGHT CHARGE SCHEME. X4040 I fear the magnetic arrangement of the old cutout is hardly suitable, the reason being that as far as we can judge it was considerably affected by the roughness of the road. I have therefore sketched a design (to follow later) of magnet very similar to the one at present used, but with an armature more nearly balanced about its centre of motion. I fear we shall not be able to pass for production the old scheme, so I want you to get this new magnet made and tested at the first possible minute. Without a tremendous amount of calculation I find it difficult to estimate the size of copper and manganin wire for the winding of the coil. The manganin wire if it is large in dia. would cost much money, and a copper if iv large in section would not allow sufficient turns before the dia. became too great. I must leave you to make a large number of trial calculations to find out the best arrangement for efficiency and economy of first cost, and current. The temperature co-efficient of the combine is naturally a rather serious matter, as the ampere turns will be forced to increase to the standard amount when the apparatus warms up, but fortunately the battery generally takes a few minutes after being switched on before the voltage rises to the cutting out point. [Signature] R.{Sir Henry Royce} | ||