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).
Dynamo tests for a 3-charge scheme when fitting a 40/50 dynamo to a 20/25 HP chassis.
| Identifier | ExFiles\Box 163\6\ img174 | |
| Date | 22th June 1932 | |
| X6016 To FN. from Hs{Lord Ernest Hives - Chair}/Wst. c. E.{Mr Elliott - Chief Engineer} HY.{Tom Haldenby - Plant Engineer} Wor.{Arthur Wormald - General Works Manager} Hs{Lord Ernest Hives - Chair}/Wst. S/KT. 22.6.32. X600 40/50 DYNAMO FITTED TO 20/25 HP. CHASSIS WITH 3 CHARGE SCHEME. We have been carrying out some dynamo tests with the 40/50 dynamo with various grades of resistance, with the idea of arranging the 3 charge system on the 20/25, with this larger size of dynamo. This is necessary for two reasons - (a) To safeguard the battery during summer running owing to the fact that the battery on the 20/25 is of smaller capacity and weight than the 40/50. (b) To avoid over-running the headlamps. The results we have obtained are as follows - With the dynamo in the full charge position arranged to operate only when the headlamps are on, the dynamo will cut-in at 9 m.p.h., and will reach a peak of 13 amps. With the dynamo arranged with one stage of resistance incorporated in the field circuit, i.e. for winter charge running, without headlamps, the dynamo will cut-in at 12 m.p.h. and will reach a peak of 9 amps. With the dynamo arranged with two stages of resistance, i.e. for summer charge conditions, the dynamo will cut-in at 16 m.p.h. and reach a peak of 6 1/2 amps. We think these resistances are about right, and should suit the dynamo battery requirements on the 20/25 chassis. At the same time the side-lamps will not tend to be overloaded as regards voltage owing to the fact that with the first stage of resistance incorporated, the maximum charge will be 2 amps. less than the present standard 20/25 HP, in the side and tail position. We wish to point out that we do not recommend with this scheme, putting the full charge on the | ||