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).
Modifications to the SS motor, including ratio changes, armature length, and engagement issues.
| Identifier | WestWitteringFiles\T\November1928\ Scan008 | |
| Date | 8th November 1928 | |
| EFC4/T8.11.28. -2- Contd. and we anticipate in the light of our later experience, a better performance from this than from the 41 slot of which the machines for the SS.{S. Smith} cars are at present made. We do not feel, however, that the best result produced would be really satisfactory when starting the engine cold with regard to the available power. In order to ease the situation you sometime ago increased the motor to engine ratio from 13 : 1 to 16 : 1. This has resulted in a smaller pinion. Both pinion and wheel are rather narrow measured axially. I think Hs.{Lord Ernest Hives - Chair} has drawn your attention in his note to the probability that the wear on the pinion may be too great. May we again suggest the possibility, seeing that we cannot increase the diameter of the motor (?), of increasing the axial length of the motor so as to gain perhaps 1" more on the armature length. Regarding the end thump on engagement and disengagement, we hope to find some means of reducing this. We hope within the next day or two to have the SS.{S. Smith} engine fitted with a new SS.{S. Smith} motor with modifications as described. It may possibly be the case with the altered armature taper and the possibility of using a spring of either different constants, that we can realise a reduction of this phenomenon. So far, as our experience of this outwardly engaging armature movement motor is limited to one of 3.100" to 2.900" armature taper and 45 slots, both of which features we believe we have proved to be wrong. EFC | ||