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).
Incorrect brush clearance on Goshawk Commutator & Brush Systems.
| Identifier | ExFiles\Box 50\5\ Scan379 | |
| Date | 28th September 1925 | |
| To BY/RD. from EFC. c. EY. X4333 EFC4/T28.9.25. X.4333. GOSHAWK COMM. & BRUSH SYSTEM. WE have recently pointed out to you the importance of correct brush in holder clearance, to prevent brushes sticking in service and you have indicated to me that the minimum clearance on the 20 HP. dynamo is .005". This should be satisfactory provided the clearance never is less than this, but on the production machines which we have just had for examination, the three minimum clearances have been respectively nil, .002", .002". I am including this in my report to Mr. Brock on the machine, but I think at the same time that you should be aware of this. It is possible, of course, that the brushes are a bit over-size. We are having these measured to make sure, and will let you know. You, however, make quite a liberal allowance between the minimum and maximum, so that it ought to be possible for the matter to be right, either by the brush makers making the brushes a little smaller, or otherwise. At any rate, it is quite wrong that the machines should be turned out with less than .005" clearance, and something ought to be done to make this impossible. EFC. | ||