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).
Summary of particulars for various electric starter motors, focusing on brush materials and performance.
| Identifier | ExFiles\Box 35\1\ scan 006 | |
| Date | 3rd April 1919 | |
| To E.{Mr Elliott - Chief Engineer} from EFC. X.2656 EFC1/T3.4.19. RE ELECTRIC STARTER MOTORS In answer to yours E2/G29.3.19., we are now sending two copies of a summary of particulars of various starter motors which was sent to Mr. Royce in its original form under our EFC5/18.4.18. We have added a few more particulars which more directly represent those for which you ask. The motors on this list are the only ones to which we have had direct access, but I think will give you what you require. You will see that all the particulars for which you ask, for instance, number of brushes, current density at start, current density at maximum power, are given and we hope this will be sufficient to cover your requirements. Hardness and grade of brushes are given where possible. As a result of tests carried out on one of our starter motors of various grades of brushes, we have standardised a grade known as (in the early days of the War) C.M.1. link Morgan-ite. These are copper carbon containing apparently a large percentage of copper. We have obtained with this brush very much better results than with any other type of Morganite brush. In making the notes on this list regarding brushes, I have used this as a sort of standard of comparison. EFC. | ||