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).
Bursting tests conducted on moulded commutators at high speeds and temperatures.
| Identifier | WestWitteringFiles\I\July1922\ Scan68 | |
| Date | 1st July 1922 guessed | |
| To R.{Sir Henry Royce} & E.{Mr Elliott - Chief Engineer} from KFC. c. to CJ. & FH. c. to By.{R.W. Bailey - Chief Engineer} & EP.{G. Eric Platford - Chief Quality Engineer} c. to Rg.{Mr Rowledge} & Da.{Bernard Day - Chassis Design} c. to Wor{Arthur Wormald - General Works Manager} ORIGINAL. EPCL/T3.7.2 X.4333 - BURSTING TESTS OF MOULDED COMMUTATORS. We have a series of tests in progress on the bursting of moulded commutators at high speeds (6000 to 6400 R.P.M) and high temperatures, 80 to 120°C. The equivalent of a factor of safety, roughly estimated as about 2 to 1, has been attained by carrying out the tests on commutators with the whole of the copper in the segments previous to turning. Two such moulded commutators were fitted up side by side on a rigid spindle in an old starter motor carcase, and driven on our dynamo rig. For each pair of commutators a cold test was at first made in which the speed was taken up to 6200 R.P.M. and maintained at this figure for three minutes. In no case, however, have we burst a commutator on this cold running. Subsequently a small electric heater unit, arranged inside the carcase, and developing about 150 watts was switched on, the end of the carcase being covered in and conveniently heat lagged in such a manner as to enable us to obtain, after about an hour, a carcase temperature approximately in accord-ance with the figures quoted The temperature was actually measured by means of an ordinary mercury thermometer, the bulb of which is contained in a little copper oil cup, which is part of an extensive copper saddle resting on the top of the carcase, and in reasonably good metallic contact with it, so that the temperature actually observed was probably | ||