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).
Correspondence regarding worn dynamo brushes on a Goshawk engine, detailing fault analysis and corrective actions.
| Identifier | ExFiles\Box 46\2\ Scan187 | |
| Date | 20th April 1922 | |
| X4086 Hy.{Tom Haldenby - Plant Engineer} from EP.{G. Eric Platford - Chief Quality Engineer} EF1/LG20.4.22. GOSHAWK-11. X4219 X4086 We have received your wire today as follows:- "PLATFORD - SIX GOSHAWK DYNAMO BRUSHES WORN OUT SEND TWO SETS - HALDENBY". To which we have replied as follows :- HALDENBY - SENDING TWO SETS DYNAMO BRUSHES TONIGHT EXPRESS POST ADDRESSED YOU LAVAL ARE YOU SURE BRUSHES WORN SUSPECT FAULTY FITTING - WRITING - PLATFORD". This fault is rather interesting as it confirms the experience which we have had with 7-Goshawk-11 now on test. The dynamo failed and the trouble was traced to the brushes not making contact to the commutator and judging by the size of the brushes they certainly appeared to have worn badly, as the brushes were very low in the brush holders. In taking up the matter with EFC., however, we find that the brushes were practically the same as new ones and action is now being taken for these brushes to be increased so that they are at least flush or projecting slightly above the top of the brush holder when new. The brush holders also seemed to be at fault and instead of the spring following the brush as it wears, the spring actually rested on a nut on the front side of the brush holder. This fault is also having the attention of EFC. The brushes we are sending to you are the Le Carbon type - grade "Z" (the same as grade "O" recommended by R.{Sir Henry Royce}) These are new brushes which have only arrived today and you will possibly see that the length is practically the same as those you are taking out, in which case it will be necessary for you to re-set the brush holder spring so as to overcome the trouble as above described. In the meantime I am pushing for deeper brushes and should be glad if you will report this matter so that it will confirm our recommendations and avoid this trouble occurring. The trouble we have had with the dynamo on 7-Goshawk-11 is an "earthing" which was due to the brush holder flexible wire clip coming in contact with the commutator cover. The clearance at this point is very small and we are asking for this point to have yours and HS{Lord Ernest Hives - Chair}'s. attention. We should be glad to have yours and HS{Lord Ernest Hives - Chair}'s views in regard to this matter also what condition the dynamo is in as regards these faults on 4/5-Goshawk 11 as it appears that these may give similar trouble and it is probably more by good-luck than good management that they have not given trouble so far. EP.{G. Eric Platford - Chief Quality Engineer} | ||