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).
Copy of a letter from SOCIETE des Etablissements L Bleriot regarding specifications for an automatic switch.
| Identifier | ExFiles\Box 48\3\ Scan234 | |
| Date | 16th April 1921 | |
| YO. X 4215 Copy of letter received from :- SOCIETE des Etablissements L Bleriot 14/16, Rue Duret, PARIS. DURET 16th Avril, 1921. To, Messrs. Rolls-Royce Co,Ltd., Nightingale Road, DERBY (England). X 4215 Ref. Wd {Mr Wood / Mr Whitehead} 3/WJ5.4.21. Dear Sirs, In answer to yours of the 31st./3/21 regarding the specifications for the electric setting of our automatic switch "compensated type" with a view to its application to Rolls-Royce Cars, we would point out that we have chosen as practical setting points some "constants" slightly different to yours. In fact, you require the magnetic to "cut-in" for a tensions of 12v.2 or 12v.8 applied between its terminals No 1 and 3; No.2 terminal being disconnected. Now, for this first point we have chosen as "cut-in" tension, 13v.3 to 13 v.5 for the following reasons :- When the battery is perfectly charged each cell has a counter electro-motive force of say 2v.2 to 2v.25, therefore if the compensated automatic switch was set to "cut-in" at 12v.2 or 12v.8 as you indicate, the battery would be able to send back a current through the dynamo and that reverse current being demagnetising can produce a Contd. | ||