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).
The design challenges and experimental testing of a No. 2B starter motor and gear scheme.
| Identifier | WestWitteringFiles\T\November1928\ Scan007 | |
| Date | 18th November 1928 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} Wor.{Arthur Wormald - General Works Manager} c. Ev.{Ivan Evernden - coachwork} SS.{S. Smith} STARTER MOTOR & GEAR, No.2B.SCHEME. We have previously referred to the fact that the fundamental dimensions of the motor, taken together with the fact of the necessity of a teazer winding, are such that it is not an easy problem to get the electrical and magnetic circuits sufficiently relatively right to permit of a reasonable efficiency and B.H.P. performance. As a result of this it is difficult to reproduce in the actual motor the performance estimated on paper, and it appears that to get the best result from a motor of this size and arrangement we have had to, as has not been previously so largely the case, fall back upon a certain amount of experimental testing of various coarsenesses and numbers of turns of field winding. We are, for instance, now nearly in a position to make tests on a 41 slot half taper armature (3.100 to 3.200") with field windings of 6½, 5½, 4½ and 3½ turns per pole, and corresponding conductor coarsenesses, the sizes of the conductors of which we have made the maximum possible cross section. This leads to complaints from the shops that the motor thus arranged is a difficulty thing to produce and would not be a good manufacturing proposition on production. We have also in hand a 37 slot armature which has been particularly carefully thought out with regard to the relative proportioning of iron to copper, slot sizes, etc. | ||