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).
Failure of Goshawk II dynamo commutators and proposing design improvements.
| Identifier | WestWitteringFiles\I\May1922\ Scan55 | |
| Date | 19th May 1922 | |
| R.R. 255A (1000) TS H.{Arthur M. Hanbury - Head Complaints} 798. 10-12-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2047 [Stamp: ORIGINAL] [Stamp: R (in a circle)] To Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to CJ. c. to EV.{Ivan Evernden - coachwork} c. to HY.{Tom Haldenby - Plant Engineer} c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to FHC. [Handwritten: Seen HS{Lord Ernest Hives - Chair}] X 4333 RE GOSHAWK II. DYNAMO. Referring to the bursting of the commutators, I under-stand that this has occurred on the dynamos only and not on the starter motor. We have noticed in the model piece sent to us that the bakelite was cracked in a way which is very likely to cause the failure experienced. We have sent an altered design in which the tendency to crack should be very much reduced, and also provision is made for supporting the bakelite before removing the band on the out-side of the commutator. Since the commutator is very nearly right one would ex-pect this to make it quite reliable especially if improved mater-ial can be found. We ought to consult the bakelite people as to whether a different material than the standard is used for this purpose, [Handwritten above 'difference': and if any] [Handwritten before 'difference': and for the (crossed out)] difference of moulding pressure. In my [Handwritten above: 2nd] [Handwritten: such (crossed out)] suggestion I have replaced much of the [Typed: micanite (crossed out), Handwritten above: Bakelite] [Handwritten insertion above 'and steel': with micanite] and steel, asking the [Typed: micanite (crossed out), Handwritten above: Bakelite] to only do compression work, and leaving the steel for the tension and other duties. If it is practical to use this arrangement we should expect this would be very much more reliable than the wholly bakelite support. My third suggestion to clear this matter up quickly for immediate production is to make the commutators in the more orth-odox and old-fashioned method, with micanite rings and steel hubs. This would be a perfectly safe policy and would be in a line with most of the European makers, (C.A.V. etc.). It is a scheme in which we should have confidence to go ahead until we had [Typed: provided (crossed out)]. (1) | ||