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).
Comparison of a standard dynamo machine with an experimental one, focusing on brush wear and output performance.
| Identifier | WestWitteringFiles\O\2April1926-June1926\ Scan087 | |
| Date | 13th May 1926 | |
| EFCL/T13.5.26. -3- Contd. brush wear, in the first instance with the ordinary standard brushes. Please find attached a blueprint of comparative average output curves of - (1) The standard machine with wide brushes. (2) The experimental machine with narrower brushes. These curves being representative of the performance on the chassis at the dynamo temperatures indicated, running at normal chassis dynamo operating voltages as represented by the scale of operating voltages at the side. This is our new schedule scale of voltages which does represent very approximately correctly the actual voltages at which the dynamo is working on the car, corresponding to the various current outputs. When testing on the bench, the operating voltage is adjusted to the correct figure corresponding to each output of the dynamo by means of a small carbon plate resistance in circuit between the dynamo on test and the reservoir battery to which the dynamo output is delivered. The temperatures referred to are those attained on the bench by running the two dynamos continuously on peak output, the narrower brush machine on 18.0 volts and the standard machine on 15.0 volts, and show very clearly the difference in the heating of the armatures (handwritten: machines) due to the change of the brushes mainly, though some portion of Contd. | ||