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).
Causes of dynamo failures on the Phantom III and proposed modifications.
| Identifier | ExFiles\Box 168a\3\ img451 | |
| Date | 26th January 1938 | |
| To MR. from MR/RC.{R. Childs} RM{William Robotham - Chief Engineer}/RC.{R. Childs}12/JH.26.1.38. PHANTOM III DYNAMOS. With reference to the memo. AHC/SED.1/LP.{Mr Lappin}17.1.38. we agree that the conditions named thereon as to the cause of dynamo failures, may be true. However, in our opinion, the cause is more likely due to local heat generated at the commutator by bad sparking, which may happen if the dynamo is subjected to prolonged running at high output conditions at high speeds. This deficiency has in the past been pointed out, and arising from it, an experimental machine to R.M.Sch.911 was produced, which gave a much superior performance at high speeds. Unfortunately, this proved to be more costly to produce and had the disadvantage of a high 'cutting in' speed: 14.8 M.P.H. compared with 11.2 M.P.H. of the standard. Without further evidence, we cannot definitely say whether the failures are due to the above, or to faulty regulator, (that is supposing the dynamo to be correct in all other respects). Even if the regulator was proved to be faulty, this in its turn may be caused by a faulty connection to the resistance coil. The latter fault has been recently taken up and a modification introduced, whereby the ends of the resistance wire are now taken direct to the terminals of the resistance base. A Depot Sheet is being issued in which action is being taken on all Phantom III cars coming into Depot, the existing resistance unit being replaced by one of the modified type. RM{William Robotham - Chief Engineer}/RC.{R. Childs} | ||