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).
Comparison table of specifications for various starter motors.
| Identifier | ExFiles\Box 61b\3\ scan0207 | |
| Date | 15th July 1929 guessed | |
| -3- Starter Motor Tables - Contd. MOTOR. X.4342V. C.A.V. SC. X.4342S Smith S5. X.4384 R.R. Goshawk X.4342L Lucas. MAGNETIC CIRCUIT. Air gap (inches) .027 .038 .015 .015 COMMUTATOR & BRUSHES. Commutator dia. 1.62 1.50 1.825 1.375 Comm. length. 1.13 .90 .95 .70 Grade & Hardness of brushes. Morgan-ite CM3 Morgan-ite CM3 Morgan-ite CM3 Morgan-ite CM3 No. of brushes. Arrgt. of brushes. 4 at 90° 2 at 90° 4 at 90° 4 at 90° Brush contact total area for current.(sq.") .490 .281 .465 .300 Advance or retard of brushes. EFC. | ||