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).
Dynamo commutation issues, specifically the development of flats on the commutator due to armature winding design.
| Identifier | ExFiles\Box 60\4\ Scan185 | |
| Date | 29th September 1933 | |
| 86099 E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to C. c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to PN.{Mr Northey} Hs{Lord Ernest Hives - Chair}/Wst.1/MA.29.9.33. DYNAMO COMMUTATION. We had complaints from Br.{T. E. Bellringer - Repair Manager} that the dynamos on our chassis develop flats on the commutator after a certain amount of running. We are aware that there is a possibility of this occurring due to the fact that some time ago in order to reduce dynamo noise an even number of armature slots was introduced. As our armature windings are multipolar series or "wave" this necessitated the introduction of a "lap" wound coil in order to symmetrically fill up all the slots with an equal number of conductors. The two segments to which the lap coil was connected, consequently induced a different potential when undergoing commutation to the rest, thus causing sparking and unequal wear. We have not noticed any appreciable effect, as a result of our limited observation of dynamos on experimental chassis, in the life of commutators before they require skimming with this arrangement of armature winding, but the flats do occur in service and the trouble experienced by our Repair Depot justifies an improvement. It is important in the interests of dynamo quietness that we retain the even number of slots and we suggest the following alternatives for your consideration: | ||