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).
Proposal to produce and test a new motor armature for the Phantom engine to address issues with the existing Bosch motor.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 140 | |
| Date | 2nd June 1927 guessed | |
| -4- Contd. longitudinal engagement. In this connection we have now decided that the Bosch motor referred to, which has a similar carcase dia. but smaller armature dia., and which has 31 slots of only one turn per coil, cannot be of suitably sufficient size for starting our Phantom engine, with the same reduction ratio of 13 : 1. This we have arrived at as a result of our thorough consideration of the matter which has led us to the conclusion of the desirability of a larger number of conductors. Our definite proposal is therefore this :- that we produce a new armature on the lines indicated, arranging this armature at the same time with a tapered surface, and the pole pieces accordingly, to suit taper dimensions already indicated by yourself. That we test this motor for brake performance as well as for longitudinal engagement, and that we do this with a varying number of field winding turns, say 4, 5, and 6, altering the section accordingly, so as always to obtain the maximum section. We have looked into the matter of the calculation of the longitudinal pull and have decided that it is impossible to give any useful paper estimate of the value of this force at various distances. The whole problem is complicated and in our opinion it will be necessary to make quite a number of tests before it is possible to get the conditions entirely right. On the present motor we are tapering the armature as much as we can, but this move can only be a temporary expedient by | ||