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).
Examination report on a faulty Dynamo DE.85 from chassis 60 RC with melted solder.
| Identifier | ExFiles\Box 70\3\ scan0286 | |
| Date | 21th March 1927 | |
| EFC. PC.130. March 21st. 1927. FAULTY DYNAMO DE.85 EX CHASSIS 60 RC.{R. Childs} The above machine was received with a complaint of solder being melted from the commutator connections. An examination of the machine resulted as follows :- (1) On the insulation test, tracking was observed taking place across carbon dust on the control brush-holder. (2) The positive brushes were well bedded and polished, but the control brushes were blackened and pitted, as also was the commutator. (3) The machine had the early control brush setting of 1200 from the positive brushes. (4) Solder had been melted from the commutator connections only. (5) The armature winding did not appear to have been overheated, but the field winding did. There are no definite indications of the cause of the solder melting. The machine probably had a high output which may have been the cause. On the other hand, from the appearance and wear of the control brushes, excessive sparking has been taking place at the control brushes, which may have caused sufficient local heating to melt the solder. EFC/D.A.Pignatt. | ||