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).
Experiment report on the effect of a sticking negative brush on a Goshawk dynamo.
| Identifier | WestWitteringFiles\K\October1923\ Scan52 | |
| Date | 4th October 1923 | |
| EFC. AB.88. 4th Oct. 1923. X.4383 - GOSHAWK DYNAMO - EFFECT OF STICKING NEGATIVE BRUSH. An experiment has been made on machine E to reproduce overheating due to a sticking negative brush, whilst operating on a normal battery circuit. The machine was first run ordinarily at maximum output whilst heat insulated on the bench rig, until the temperature became steady. This was at 77ºC. The operating particulars were :- Dynamo speed 1550 r.p.m. Amperes delivery 9.3 Main volts 14.75 Field volts 6.3 The negative brush was next made tight in its holder by being packed with a piece of paper, and a very light spring was fitted, so that fairly bad sparking took place. In this way the machine rose to a temperature of about 90ºC, and the operating particulars, though not very steady were approximately :- Dynamo speed 1550 r.p.m. Amperes delivery 10.0 Main volts 14.8 Field volts 8.5 The negative brush surface became a little rougher than usual, and the commutator surface was slightly pitted, although the solder was not thrown. RJA. | ||