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).
Specification table for 26 slot dynamo armature windings for 20 HP and 40/50 HP models.
| Identifier | ExFiles\Box 68\4\ scan0080 | |
| Date | 14th April 1928 | |
| X8664 14.4.28 PARTICULARS OF 26 SLOT DYNAMO ARMATURE WINDINGS. 20 H.P. 40/50 H.P. Type of winding. Ret. wave. Ret. wave. No. of slots. 26 26 No. of conductors. 312 312 Conductors/slot. 12 12 Coils/slot. 2 2 No. of coils or comm. bars. 52 52 Turns/coil. 3 3 Virtual conductors. 104 104 Winding pitch in virtual conductors. 29 & 21 25 Step or winding pitch in slots. 5 (1 to 6) 6 (1 to 7) Armature resistance (18ºC) Conductor dimensions. .048" (18 S.W.G.) .056" (17 S.W.G) Commutator diameter. 2.10" 2.20" " length. 1.20" 1.140" Brush contact area 2x.500x.300=.300 sq.ins. 2x.500"x.280" = .280 sq.ins. EFC. | ||