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).
Wear test of two sets of brushes on a Goshawk Dynamo with two coils per slot.
| Identifier | WestWitteringFiles\L\2Jan1924-March1924\ Scan84 | |
| Date | 15th February 1924 | |
| EFC. AB.103. 15.2.24. X.4610. WEAR TEST OF BRUSHES ON GOSHAWK DYNAMO WITH TWO COILS PER SLOT. Two sets of Z brushes have now run on machine B on the direct coupled rig, for the usual period, one standard the other with brushes of about two-thirds of the standard thickness at the contact surface as reported AB.100.24.1.24. The standard set ran with slight sparking all round; the main brushes acquired a very good polish, but with the trailing edges rather dull, the control brush was slightly inferior. The commutator was left a well polished light brown, but with a slight amount of blackening at the trailing edges of some of the segments. The brush wear was:- Positive .002", Negative .002" Control .005" The set of thinner brushes also sparked slightly all round, acquired an equally good or better polish, and left the commutator a polished light brown, with very little trace of blackening. The wear, however, while being less than occurs on a standard machine (one coil per slot and full width brushes) is more than takes place on this machine with the standard brushes. The figures are :- Positive .0055" Negative .005" Control .0115". EFC/RJA. | ||