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).
Insert for the 20/25 HP Chassis Handbook detailing a revised wiring diagram and switchbox modifications.
| Identifier | ExFiles\Box 163\6\ img284 | |
| Date | 16th June 1933 guessed | |
| (Insert in 20/25 H.P. Rolls-Royce Chassis Handbook, facing page 92, in conjunction with the Revised Electrical Wiring Diagram). REVISED WIRING DIAGRAM. The accompanying wiring diagram incorporates the following modifications:- Accessory Distribution Box. (See Leaflet No.21/20/25, page 106). Connections of Electrical Fuel Gauge. (See Leaflet No.23/20/25, page 118). Relay-operated Starter Switch. (See Leaflet No.24/20/25, page 116). In addition to the above, provision is now made for varying the charge rate to suit Winter and Summer conditions, respectively, as described hereunder. Switchbox. Owing to the presence of two field resistances, the switch positions are modified as compared with those described on page 98, as follows:- Off. - No circuits in action. S. & T. - Side and tail lamps on and one of the two field resistances short-circuited to provide a dynamo output equivalent to that with the charge switch in the Winter position. H.S. & T. - Head, side and tail lamps on and both field resistances short-circuited to provide maximum dynamo output. I. & C. (Summer). Ignition on, (battery or magneto, as the case may be), fuel gauge on, and connections closed to enable the dynamo to charge the battery at a reduced rate suitable for Summer conditions, both resistances being in series with the field circuit. I. & C. (Winter). The same as I. and C. (Summer) except that one of the two field resistances is out of action, the dynamo therefore charging the battery at an increased rate, suitable for Winter conditions. It will thus be seen that the two field resistances provide for three different dynamo outputs, namely:- | ||