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).
Analysis of a burnt-out dynamo from chassis 64-HC, detailing the suspected cause and extent of the damage.
| Identifier | ExFiles\Box 70\3\ scan0256 | |
| Date | 23th November 1926 | |
| To EY. from EFC. c. Sft{Mr Swift}/Mr. Brock. Mr. BGroup X8793do EFC2/T23.11.26. DYNAMO AP.55 - EX CHASSIS 64-HC. Reference your notes EY11/H15.11.26 and EY14/H15.11.26. We think there can be no question that the burn-out of this dynamo has resulted from an incomplete dynamo-battery circuit. We notice that on the distribution box sent to us with the machine, the main or emergency fuse is in a fused (broken circuit) condition, and it would appear to be extremely likely that this was done by some short circuit previous to the dynamo having been removed. We are of the opinion that the dynamo has been running and switched on since the parting of this emergency fuse. The effects of overheating on this dynamo are not those that would have been arrived at by bad commutation and sparking on the commutator locally, melting the commutator solder, but they are a complete charring of the armature resulting in a number of the armature coils being metallically dead short-circuited, though the commutator and brush gear is in perfectly good condition, (which incidentally speaks well for the 57 segment commutator). In addition, various other points to be noted are :- (1) Solder has been melted from the banding wires on the pulley end of the armature. (2) The control brush has the very early setting of 124° of angle from the main positive brush, a setting which would actually cause the machine to have a smaller output than our present standard. (3) The shunt coil of the cutout shews signs of excessive heating. over Contd. | ||