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).
Instructions for modifying an auto-switch with an extra field circuit coil.
| Identifier | ExFiles\Box 59\1\ Scan234 | |
| Date | 30th January 1928 | |
| RR 239 (150 BKS.) (SH57.29-6-20.) MP 224358 X. 4008 ROLLS-ROYCE LTD. INSTRUCTIONS. To: EFC Order No. AC.98. Customer's No. X 4008 Date: 30 Jan 1928 Auto-Switch A with Extra Field Circuit Coil. This auto-switch has been re-wound with an additional coil consisting of 360 turns of 30 swg, Eureka for connection between the distribution board terminal C and the dynamo control brush. The ordinary field resistance coil is wound with 12 feet of 30 swg Eureka in 42 turns and having a value of 21.0 ohms. The object of the extra coil is to set up additional traction to that set up by the shunt coil connected across the battery, on the armature, in the event of a break in the negative side of the dynamo supply which otherwise might entail damage to the dynamo, and possibly, the cut-out shunt coil. Signed (Cont'd) This Sheet must be filed on completion of the work. | ||