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).
The Goshawk dynamo's commutation, focusing on the surface condition of the positive brush at reduced output.
| Identifier | ExFiles\Box 50\5\ Scan212 | |
| Date | 23th August 1923 | |
| To R & E.{Mr Elliott - Chief Engineer} from EFC. c. CJ. & PN.{Mr Northey} c. Da.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} EP.{G. Eric Platford - Chief Quality Engineer} X.4333 - GOSHAWK DYNAMO - COMMUTATION. Herewith please receive a copy of my assistant's report on the running of the Goshawk dynamo with reduced output, from the point of view of commutation, more particularly with reference to the positive brush which is the one that shows a tendency to have a rough in place of a polished surface. It appears from this report that with the reduced current density, a polished surface is more likely to be in evidence on the positive brush, though with a rough surface once formed, the reduced output does not appear to be able to correct this. Largely with the idea of making more certain of the running of positive brushes with polished surfaces, we are, in the new 20 H.P. design, allowing 20% increase of total brush contact area. As stated in the report, we have one dynamo on a chassis which, even with the present output, runs continuously with a polished positive brush working surface. We shall investigate this machine with a view to finding out the reason for the polish in this case. Protracted tests of Goshawk dynamo brushes of other compositions are in progress. EFC. AB*79 att. | ||