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).
Investigation report into a faulty dynamo from chassis 7-LC, detailing issues with solder, sparking, and overheating.
| Identifier | ExFiles\Box 70\3\ scan0284 | |
| Date | 15th March 1927 | |
| PC.129. VID FAULTY DYNAMO U.J.45%. EX CHASSIS 7-LC. The complaint with this machine was also that of throwing the solder from the commutator connections. The following observations were made:- (1) Insulation tested on A.C. mains O.K. (2) The control brush angle was found to be about 12° from the positive brushes, so that the output was probably only a little higher than standard. (3) Both positive and negative brushes were well bedded and polished. The control brushes were somewhat blackened. (4) Overheating appeared to have been confined to the commutator; the armature and field windings being O.K. (5) Some of the rivets securing the insulating band inside the end cover were found to be loose. (6) The lower portion of the positive holder and the surface of the end plate close to it, were found to be covered with the coloured deposit that usually accompanies an arc. A similar discolouration was also found on the control brush holder, while the head of the positive terminal screw, projecting through the end plate, was marked in one place as though an arc had been struck on it. There is little doubt about severe sparking having taken place at the positive and control brushes. EFC/C.A.Pignatt. | ||