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).
Table of currents at various speeds for a Smith (T & M) Type 'A' Dynamo, including a circuit diagram.
| Identifier | WestWitteringFiles\C\August1919\ Scan53 | |
| Date | 1st July 1919 | |
| R.R. 235 A (100 T) (S.F. 575. 16-4-19) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2354. 1.7.19. SMITH (T & M) TYPE 'A' DYNAMO. TABLE OF CURRENTS. Headers: Speed. Main current (M) Field current (F) Control current (C) (handwritten: control brush current) Main brush current (M+F-C). Data: Speed | Main current | Field current | Control current | Main brush current 580 | 0 | 2.8 | -1.4 | 4.2 750 | 5.65 | 3.0 | 2.65 | 6.0 1000 | 11.0 | 3.2 | 8.0 | 6.2 1250 | 12.45 | 3.2 | 10.95 | 4.7 1500 | 12.9 | 3.25 | 12.75 | 3.35 1750 | 12.95 | 3.2 | 13.6 | 2.55 2000 | 12.65 | 3.2 | 14.05 | 1.8 2250 | 12.45 | 3.2 | 14.4 | 1.25 2500 | 12.05 | 3.2 | 14.65 | .6 2750 | 11.9 | 3.15 | 14.9 | .15 3000 | 11.8 | 3.1 | 15.1 | -.2 3250 | 11.7 | 3.1 | 15.3 | -.5 3500 | 11.6 | 3.1 | 15.35 | -.65 Diagram labels: M+F-C C A- M- A+ M+ Maximum current 15.35 amperes. Brush contact area = .75 x .375 = .281 Amperes per square inch (max) = 54.6 | ||