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 results of testing asbestos-filled powders and different shapes of commutator segments.
| Identifier | WestWitteringFiles\I\July1922\ Scan71 | |
| Date | 1st July 1932 | |
| Contd. -4- RPCL/FS.{F. Steele}7.32. From the above results it would appear that the asbestos filled No 1a is the most satisfactory of the powders though this is not considered to be the case by Mr. Brock, who looks upon the fact that one of these commutators has stood up throughout a number of the tests as a freak result. (N.B. This particular commutator was not burst at all after six consecutive tests). It has been noticed, for instance, that on the broken portions of the commutators the moulding material in filling in round the neck of the commutator segment has in some instances become frozen and does not present the same cross sectional texture, inclining to appear spongy. This Mr. Brock considers he has overcome in the latest pair of commutators given to us for test, the results of which must be included in a further report. He considers that it will not be possible for us to burst these under the same conditions of temperature and speed. It is possible that in the case b, the absence of failure was due to the absence of sponginess round the neck. The shape of the commutator segments (No.2 sample) on the commutators which have burst on the machines in use, was different from the shape now under test (No.3) in having much narrower grooves at the neck of the segment. We have for two commutators to be made up with segments of this shape for test under the same conditions in order to d a basis of comparison. Cont.d | ||