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).
Results of wear tests on Standard 'Z' Le Carbone and ECO Morganite brushes.
| Identifier | WestWitteringFiles\K\October1923\ Scan73 | |
| Date | 22th October 1923 guessed | |
| Contd. -2- EFC6/T22.1033. resistance, was caused to start, run slowly for a short while, accelerate to a high speed, and then stop for a few seconds, repeatedly, the period being such that about three cycles per minute were performed). Each set of brushes was started with the commutator newly clean and the following results were obtained:- Standard 'Z' Le Carbone Brushes. These run, as is known and described on p.2. of our EFC1/T27.6.23, with no undue amount of sparking, with the negative and control brushes characteristically well bedded and polished and with the positive brush with bright leading edge, and the rest of the surface rough though bedded. The commutator was left rather blackened but uniformly so. The wear was :- Positive brush .035" Negative " .025" Control " .020" ECO Morganite Brushes. These ran with no excessive sparking and left the commutator a uniform dark brown. The positive was polished on the leading part (about one third) of its surface. The negative and control brushes are smooth with the characteristic bright leading edges. The wear is positive .011", negative .009" and control .040". The spring pressures were a little on the light side when this test was run. EFContd. | ||