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 and performance ratios for the Sequence Starter Motor No. 2 scheme.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 125 | |
| Date | 24th May 1927 | |
| To R.{Sir Henry Royce} from EFC. c.c. RJ. EFC6/T24.5.27. SEQUENCE STARTER MOTOR NO. 2. SCHEME. X7625 Further to our EFC3/T18.5.27, to get an increase of .050" of air gap from .0125" to .0625" in the travel of .800" requires a larger taper on the pole pieces and armature than can be obtained without building up a new armature. We are however, as a preliminary test, obtaining as much taper as it is possible to get on the poles and armature of the present machine, for which purpose we are packing out the pole pieces to suit. It incidentally eases the winding space. From the various calculations we have made, we are of the opinion that in view of the utilisation of some of the field winding space for a teazer winding which does not function when the motor is working at full power, the ratio of armature to carcase diameter should be less than would otherwise be the case, not only from the point of view of getting a suitable ratio of longitudinal pull to stall teazer torque, but in the first instance as a result of our various brake test results which we have conducted. The ratio referred to on motors without teazer windings we note to be anything from .60 up to as high as .70, the average being round about .63. Our own 6" motor has a ratio of .60. The 20 HP. has a .63, and our sequence motor as at present arranged, .62. The only motor with teazer windings of which we have particulars is the Robert Bosch, and in this case the ratio is .56. Contd. | ||