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).
Design of an actuating magnet, its windings, and components.
| Identifier | ExFiles\Box 64\1\ scan0169 | |
| Date | 6th March 1924 guessed | |
| (2) We have arranged convenient copper strips and connec-tions and this rush should ensure the magnet acting against a good pull off spring which is necessary for establishing a good contact for the current going to the actuating magnet. After the armature has been pulled down a small current will hold it down but the gauge of wire for this secondary winding I do not know. Make it fine enough to not roast in any time it is likely to be on, and coarse enough to ensure the magnet hold-ing its armature against the spring mentioned earlier: perhaps about 10 ohms would be about right. There should be no mistake about this scheme being about right straight away, but some good judgment will be required to criticise and modify it quickly, but I have indicated the object and the limi-tations fairly clearly. There is only the one non-inductive re-sistance mentioned that I can see any need or advantage to have. Mr. Clarke will look into this matter. R.{Sir Henry Royce} | ||