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).
Modifications to 40/50 & 25HP dynamos and electrical circuits for improved performance.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan202 | |
| Date | 19th May 1931 | |
| ORIGINAL HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} C to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} RY. 40/50 & 25HP. DYNAMOS. R3/M19.5.31. X6099 Referring to HS{Lord Ernest Hives - Chair}/PGT1/AD16531. and HS{Lord Ernest Hives - Chair}/FGT2/AD16531., we are very pleased to hear that the Elec: Dept. are tackling the matter of output more vigorously. Summer, and winter, and head lamps, and no head lamps, makes 4 conditions seem quite useful, and during winter the temperature would be lower and therefore the dynamo less liable to overheat. I suggested some time ago, and PN.{Mr Northey} agreed, that it would be good if we could use some series winding to maintain the voltage, and in my suggestion it was to be in the headlamp circuit. I also suggested that the dynamo was probably hotter at the slower speed when the output was greater than it was at the high speed when the output and magnetism hysterisis would be less, in which case the increased high speed output would do no harm as regards temperature. The series winding would have the advantage that as soon as the machine cut in the curve would rise rather more steeply and maintain itself more level. Naturally it would be better if it were in the circuit of the headlamps, but if that would cause too much complication, might merely be in circuit with one of the main brushes for the purpose of keeping up the output at high speed. This is now considered necessary for fast night running. For some time it was not clear that the output increased with the battery voltage, and realising this one can see that it is an advantage to cut out the extra resistance when switching on the headlamps. In the past, unknown to WW., 60 W. lamps were installed in place of the original 30 W. and naturally these demanded twice the current and would probably give very much less light when the battery became low in charge than would be the case with 36 or 45 W. lamps. The series winding in connection with the brush would not add to the complication and would provide a great help for fast continental night travelling. The two rate scheme would make the necessary difference for when the headlamps were switched on. The same field resistance, or an extra field resistance could be controlled by a separate hand switch for summer and winter work. I think for simplicity the series winding should be permanently connected. [STAMP: RECEIVED 21 MAY 1931] | ||