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 performance and potential improvements for the No. 2B Scheme Sequence Starter Motor and Gear.
| Identifier | ExFiles\Box 64\2\ scan0196 | |
| Date | 10th October 1928 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} EY. V7621B EFC4/T10.10.28. SEQUENCE STARTER MOTOR AND GEAR. NO.2B. SCHEME. V7655B We have now had considerable experience of the above on chassis 9-EX. The motor in question is the first of the outward sliding armature type, having 45 armature slots, 6¼ field turns per pole, armature taper 3.100 to 2.900, helix angle 5°, and 16 : 1 ratio of the engine. The functioning of this apparatus has not been entirely satisfactory and our observations indicate fairly clearly that there are directions in which the apparatus can be improved, these directions not relating to alterations in main design, but to alterations in certain quantities involved. The item which is most easily variable on the system is the strength of the main armature spring, and the fact that we have been able to vary this has enabled us to arrive at more definite conclusions regarding the required alterations, than would otherwise have been the case. It may perhaps be convenient to distinguish between:- I. Failure to operate. II. Unsatisfactory characteristics in operation without failure. In regard to I, the principal failure has been that the rotational torque on the armature when the teeth are about to engage has not been invariably sufficient in relation to the longitudinal pull to overcome the friction between the ends of the teeth and so turn the pinion into engagement. At the same time the main spring of strength suited to the present arrangement in respect of other quantities has not been | ||