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).
Specifications table comparing two starter motors, a Robert Bosch and an R.R. E.A.C model.
| Identifier | ExFiles\Box 61b\3\ scan0204 | |
| Date | 10th November 1927 guessed | |
| -3- Contd. Starter Motor Tables - Contd. | | X.4562 Robert Bosch. | X.8620 R.R. E.A.C. | |---|---|---| | MOTOR | | | | MAGNETIC CIRCUIT. | | | | Air gap (inches) | .015 | .0125 | | COMMUTATOR & BRUSHES. | | | | Commutator dia. | 1.875 | 2.10 | | Comm. length. | Long. comm. for sliding arm: | 1.00 active. | | Grade and hardness of brushes. | ET10A Similar to Morganite CM.3. | CM.3. Morganite. | | No. of brushes. | 4 | 8 | | Arrgt. of brushes. | 4 at 90° | 4 prs. at 90° | | Brush contact total area for current (sq.") | 1.25 | .592 | | Advance or retard of brushes | | | EFC. | ||