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).
Test report comparing the performance of moulding materials, Bakelite and Mouldensite, for commutators.
| Identifier | WestWitteringFiles\I\July1922\ Scan91 | |
| Date | 12th July 1922 | |
| -2- Contd. Date of Test | Moulding material | Ref. Lettr. | Carcass Temp. reached Previous to speed burst | Test speed | Duration of speed Test (min) | Result | Further remarks --- | --- | --- | --- | --- | --- | --- | --- 7.7.22. | 1. Bakelite. | k | 130° | 6000-6400 | 18 | 6 segments flew out. | Solder unaffected. 7.7.22. | 2. Mouldensite | i | 130° | 6000-6400 | 18 | Segments O.K. but comm. had loosened & moved on ferrule. | Solder melted. N.B. Owing to the arrangement of the heater the two commutators on test together would not be precisely at the same temperature and in cases where the solder melted it is invariably on the comm. which would be at the higher temperature. 12.7.22. | 1. Mouldensite. | i | 135° | 6000-6450 | 4 | O.K. | Solder unaffected. 12.7.22. | 2. " | i | 135° | 6000-6450 | 4 | O.K. | Solder melted. 12.7.22. | 1. " | i | 135° | 6000-6500 | 10 | O.K. Solder unaffected. | 4 minutes at 6000 and 6 mins. at 6500. 12.7.22. | 2. " | i | 135° | 6000-6500 | 10 | O.K. | N.B. Mouldensite commutator (ref. i) had six 1/4" radial holes drilled in the ferrule so that the moulding material could run into these holes, the idea being to prevent the commutator coming loose on the ferrule, as happened in two cases on test. previous. EFC. | ||