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).
Summary table of particulars for armature and field windings of various starter motors.
| Identifier | ExFiles\Box 61b\3\ scan0053 | |
| Date | 26th April 1917 guessed | |
| X. 543 SUMMARY OF PARTICULARS OF ARMATURE AND FIELD WINDINGS OF STARTER MOTOR (ALL OF THE FOUR POLE TWELVE VOLT TYPE) (ALSO OTHER DATA) (except Bijur which is 6 volt) MOTOR: | Lucas A.S10. | C.A.V. | R.R.45 | R.R.17. | R.R.24. | Bosch. | Bijur --- | --- | --- | --- | --- | --- | --- | --- ARMATURE No. of slots. | 43 | 21 | 45 | 17 | 24 | 41 | 21 No. of com. bars. | 43 | 21 | 45 | 51 | 48 | 41 | 21 No. of coils. | 43 | 21 | 45 | 51 | 48 | 41 | 21 No. of conductors. | 86 | (84 (42 virtual | 90 | 102 | (384 actual (96 virtual. | 82 | 84 42 virtual No. of turns per coil. | 1 | 2 | 1 | 1 | 2 | 1 | 2 No. of conductors in series per coil. | 2 | 4 | 2 | 2 | 4 (and 2 in) (parallel) | 2 | 4 No. of conductors per slot. | 2 | 4 | 2 | 6 | 16 actual 4 virtual. | 2 | 4 Winding pitch. a.{Mr Adams} conductors. | 21 | 22 i.e. 2 x 11 | 23 | 25 | 25 virtual conductors forward. 23 ditto backward. | 21 | b. slots. | 10 & 11 | 5 & 6 | 11 & 12 | 4 & 5 | 5 & 6 | 10 & 11 | Type of winding. | Retrogressive wave. 2 circuit. | Progressive wave. 2 circuit. | Progressive wave. 2 circuit. | Retrogressive wave. 2 circuit. | Lap 4 circuit. | Progressive wave. 2 circuit. | | ||