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).
Performance graph of a 20 HP dynamo showing output with various main brush positions and armature types.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan139 | |
| Date | 28th August 1925 | |
| AMPERE OUTPUT SCHEDULED OPERATING VOLTAGES OUTPUT of 20h.p. R DYNAMO WITH TWO & THREE COIL PER SLOT ARMATURES FOR VARIOUS MAIN BRUSH POSITIONS Two coils per slot (29 slots) 1. Main brushes 7° retarded. Temp. rise 55°c. Control brush 114.5° from positive. Dynamo Carcase E 2. Main brushes 9° retarded. Temp. rise 54°c. Control brush 119° from positive. Dynamo Carcase B Three coils per slot (19 slots) 3. Main brushes 7° retarded. Temp rise 52.5°c. Control brush 114.5° from positive. Dynamo Carcase E 4. Main brushes 9° retarded. Temp rise 53°c. Control brush 118° from positive. Dynamo Carcase B 5. Main brushes 11° retarded. Temp rise 54°c. Control brush 120° from positive. Dynamo Carcase B (Two coils per slot) 6. Main brushes 7° retarded. Temp rise 48°c. Control brush 120° from positive. [Representative Standard] Air gap in every case .015" Specified performance DYNAMO R.P.M. H.N 1.11.24 E.F.C 28.8.25 | ||