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).
The failure of Dynamo Brushes in 4-GII electrical equipment.
| Identifier | ExFiles\Box 51\1\ Scan140 | |
| Date | 26th March 1923 | |
| X.4383. Extract from EFC {E. Fowler Clarke - Electrical Engineer} 4/T26.3.23. 4-GII ELECTRICAL EQUIPMENT. X.4333 (2) Failure of Dynamo Brushes. We regret this X.4383. failure. You will remember we reported to you in our EFCl/T2.12.22 some dissatisfaction with the commutator and brush system on the Goshawk dynamo and we had hoped that with improved dimensions of brushes and brush holders this fault would be overcome. Since that time the dimensions of the holders have been improved and the brush dimensions have been improved by more rejections. We have sometime ago deleted the coppering with which the brushes were originally capped, and this in itself makes for more accurate dimensions, In spite of all this, however, we are still not perfectly satisfied with the commutation and we think a good deal of this is due to want of rigidity in the brush holders. Could we not have a more rigid design ? We think that excessive wear has been caused in those instances in which it has occurred by the brushes being gripped in the brush holders (due to inaccurate dimensions or 'growing') just tightly enough to prevent the full pressure on the commutator, but loosely enough to allow the spring to maintain them in partial contact, the contact surfaces sparking badly during the process. If so, this should be overcome by the more exact dimensions now obtained. A case of this sort had just been brought to my notice on a dynamo on one of the experimental cars. No definite complaints of similar | ||