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 four-pole dynamo, detailing its construction, materials, and performance, especially in hot conditions.
| Identifier | WestWitteringFiles\E\November1920\ Scan54 | |
| Date | 17th November 1920 | |
| EFC1/T17.11.20. -2- Contd. For the fully hot condition and for the later portion of the curve the performance is not good [handwritten 'X' and '39/40' over text], as will be seen on inspection of the curve. The machine is a four-pole with a single exciting winding connected as indicated in the diagram between one main brush and an auxiliary [handwritten] the control brush, in the neighbourhood of the other main brush. It is made with a circular steel carcase, outside dia. 5.750", length 4.375", and thickness .315". The commutator and bearing end plates are aluminium castings giving a pleasing appearance to the machine. The brush holders are insulated with mica and attached to the end plate in what would appear to be quite a satisfactory manner. The brushes are of C.4 Morganite which is a very hard and dense carbon brush. The general running of the commutator and brushes throughout our tests was excellent. The dynamo is fitted with self-aligning ball bearings and there is a fibre disc between the bearing and the commutator, slightly larger in diameter than the commutator itself, which effectually prevents grease finding its way to the commutator. The machine runs very well and except for one or two minor points would, perhaps, be quite suitable as regards finish and construction for R.R. purposes, but the performance curve of the machine would make it unsuitable for this purpose particularly when in the fully hot condition. It is interesting, however, to compare the performance of a machine controlled in this manner with the performances of the Lucas and Smith machines controlled in their respective manners and for this purpose we have drawn curves of these other Contd. | ||