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 proposed standard sizes for dynamos and motors for large and small cars.
| Identifier | ExFiles\Box 61b\3\ scan0123 | |
| Date | 22th April 1921 | |
| PROPOSED STANDARD R.R. DYNAMO & MOTOR SIZES. X.294. X.543. Carcase dia. | Armature dia. | Air gap. Dynamo for Large car. | 6.00" | 3.50" | .015" Dynamo for Small car. | 5.25" | 3.00" | .012" Motor for Large car. | 5.25" | 3.00" | .015" Motor for Small car. | 4.75" | 2.75" | .012" Handwritten notes: Obsolete See similar sheet - 5.7.21. EPC. L2092 X543 | ||