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).
Testing narrower brushes on Goshawk dynamos with two coils per slot.
| Identifier | WestWitteringFiles\L\2Jan1924-March1924\ Scan85 | |
| Date | 24th January 1934 | |
| EFC. AR.100. 24th Jan. 1934. X.4610 - NARROWER BRUSHES ON GOSHAWK DYNAMOS WITH TWO COILS PER SLOT Machine B as above, after test with the standard brushes, was fitted with brushes filed away equally on each side, so as to have only about two-thirds of the standard circumferential contact, allowing the main brushes to cover about 1.7 segments and the control 1.1, instead of 2.6 and 1.7 respectively on this machine and 1.3 and .9 on machines with one coil per slot. On load, this machine reached 76°C maximum and gave a peak output of 11.0 amps, as compared with less than 10.5 amperes with the standard brushes. The brushes were as free from sparking as the standard brushes, (i.e. a great improvement on the one coil per slot construction) and acquired equally polished surfaces. EFC/WJA. | ||