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).
Performance issues and design considerations for a sequence starter motor following a change in reduction ratio.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 137 | |
| Date | 2nd June 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. ORIGINAL EFC4/T2.6.27. SEQUENCE STARTER MOTOR NO. 2. SCHEME. The reduction through which this 5" dia. motor was originally arranged to drive the engine was 30 : 1, and all the electrical quantities in the design were very easy with the given armature dimensions and assumed characteristic of supply. Correspondingly, on brake testing the motor, its performance at low motor torque and high speeds was reasonably satisfactory. At heavier torque loads, however, the performance of the motor did not come up to expectations. With the change to the 13 : 1 ratio, the problem arose as to how to improve the performances of the motor under the heavier loads, and as a result of calculations, the windings were rearranged. In the meanwhile further tests were made on existing motors with varied windings, in anticipation of some improvement, but little improvement was observed. The reason for this we attribute to the fact that in this size of motor, especially under these high loads and with the special arrangement of field windings required, there is very little freedom or margin in electrical and magnetic design. As a result of tests and observations generally, we have recently again thoroughly considered the whole matter and done our best to arrive at what we hope may be a satisfactory solution of the problem in the special circumstances of the case. Contd. | ||