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 for an armature and field winding, detailing slot dimensions, wire gauges, and air gap.
| Identifier | ExFiles\Box 68\4\ scan0207 | |
| Date | 23th March 1920 | |
| Contd. -2- EFC4/T23.3.20. (2) This armature will be cut with 45 slots of narrower and deeper section than the previous. The winding for this is to consist of 540 conductors of No.19 S.W.G. D.C.C. wire, composed of 45 sections of 6 turns per section arranged in the manner also diagrammatically illustrated. It is estimated that the slots will be .080" wide and .675" deep, but they should be as much less deep as possible. The winding for this will be a four pole progressive wave winding, the winding diagram of which is exactly the same as that for the starter motor with the exception that each section consists of 6 turns instead of one turn, thus the step of the winding will be 1 to 12 and the commutator as at present made for the starter motor will come in for this armature. The air gap is to be not more than .020" and as little as .015" if this can be arranged. This fixes the exact external diameter of the armature at a little greater than for the starter motor (3.625") of which the air gap is .025". The field winding is to consist in the first instance of No. 20 S.W.G. D.C.C. wire and it is desired to get as many turns as possible of this wire in the space available. The coils for the four poles will, of course, be joined in series constituting a single shunt winding. Contd. | ||