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 bench and road tests of modified dynamo brush springs to reduce noise.
| Identifier | ExFiles\Box 62\3\ scan0244 | |
| Date | 9th September 1931 | |
| X6066 By.{R.W. Bailey - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Pgt. Hs{Lord Ernest Hives - Chair}/Pgt.1/AML.9.9.31. DYNAMO BRUSH SPRINGS. As a result of bench tests carried out some time ago on the 40/50 dynamo with a view to reducing brush noise as much as possible, it was found that some improvement was obtained with both a brush having an increased bevel angle and a specially shaped spring. Subsequently, two sets of the modified spring were made and run on the bench and on cars in conjunction with brushes having various bevel angles. Originally, it was intended that the new spring and the finally approved brush should be put forward for standardisation together. As however, the spring has been well tested and proved satisfactory and there is more to be done on the brush before a satisfactory type can be decided upon, we suggest that the spring go forward for standardisation by itself. Another reason for this recommendation is that a certain amount of trouble from brush noise is being experienced (both on 40/50 and 20/25), and in many of the cases the spring has been at fault. The modified spring is substantially the same as the present one, being merely a slightly different shape having a more definite area of contact with the brush and giving more clearance where it passes over the back of the brush from behind. It may, therefore not be necessary to take out a standardisation sheet. The modification to the spring can be applied to both dynamos and may be brought in at any convenient time. As regards road tests, two sets have been run as follows :- No.1 set - ran over 11,000 miles and has now completed a second run of 10,000 miles on 14-EX. No.2 set - ran nearly 12,000 miles on 21-EX. Hs{Lord Ernest Hives - Chair}/C.A.Pignatt. | ||